Evolution of Mastigitae: Mesozoic and Cenozoic fossils crucial for reclassification of extant tribes (Coleoptera: Staphylinidae: Scydmaeninae)

Evolution of Mastigitae: Mesozoic and Cenozoic fossils crucial for reclassification of extant... Abstract Mastigitae is a supertribe of ant-like stone beetles (Scydmaeninae) that includes over 40% extinct genera, and whose evolutionary history is documented from the Upper Cretaceous through to today. Based on the results of phylogenetic analyses combining the most extensive taxon sampling to date, we reclassify Mastigitae into six monophyletic units: Leptomastacini, Clidicini sensu nov., Papusini trib. nov., Leptochromini trib. nov., †Baltostigini trib. nov. and Mastigini sensu nov. †Cretoleptochromus is placed as a junior synonym of Clidicus, and †Cascomastigus as a junior synonym of †Clidicostigus. Euroleptochromus setifer sp. nov. and Baltostigus striatipennis sp. nov. are both described from Upper Eocene Baltic amber. We postulate that Mastigitae have undergone differentiation into major lineages before the Cenomanian and that the Eurasian part of Laurasia was their ancestral distribution area. The reconstructed ancestor of Mastigitae was similar to the extant Scydmaenini, but with broadly separated antennal insertions and deep elytral striae. Four independent wing losses were inferred in Mastigitae. We present the first complete μCT reconstruction of the aedeagus in a fossilized scydmaenine, crucial for understanding the more than 99 million year long evolution of one of the most bizarre, asymmetrical aedeagi in the Coleoptera. beetle, Cretaceous, Eocene, male genitalia phylogeny, taxonomy INTRODUCTION Mastigitae is one of three currently recognized supertribes within the extant ant-like stone beetles (Staphylinidae: Scydmaeninae). It comprises three tribes, Clidicini, Leptomastacini and Mastigini, with nine extant genera and 126 extant species (Jałoszyński, 2016a). Fossils, including seven extinct genera, have been described from Cenomanian, Campanian, Priabonian and Miocene/Oligocene amber (summarized by Jałoszyński & Perkovsky, 2016 and Jałoszyński et al., 2017a). Among the scydmaenines, Mastigitae species show an unusually broad spectrum of morphological structures (examples of extant and extinct forms are shown in Figure 1) and ecological adaptations. For these reasons, they attract much attention. Mastigitae include the largest adult beetles among the Scydmaeninae, reaching 1 cm of body length and dwarfing most others of the subfamily, which do not exceed 2 mm and often do not reach 1 mm. Extant species of Clidicini include small (∼1.6–3 mm), flattened and lightly pigmented beetles that live under stones in the most arid deserts of North America and large (up to 1 cm), darkly pigmented and strongly convex beetles associated with leaf litter in humid Oriental, Australian and Neotropical forests (Fig. 1A). One genus, placed as incertae sedis, but possibly closely related to Clidicini, was recently found in Cenomanian Myanmar amber (Fig. 1B); other extinct forms are known from the Campanian of Canada, the Upper Eocene of north-central Europe (Fig. 1C, D) and the Miocene/Oligocene of Chiapas, Mexico (O’Keefe et al., 1997; O’Keefe, 2002; Jałoszyński, 2012a; Jałoszyński & Perkovsky, 2016; Cai & Huang, 2016; Yin et al., 2017a). Extant Mastigini are long-legged beetles with a conspicuously enlarged and spiny scape and pedicel; they have diurnal adults that often live in dense populations and run on the ground or climb bushes and trees. The recently discovered Cenomanian †Clidicostigus Jałoszyński et al. and †Cascomastigus Yin & Cai from Myanmar amber had a monstrously enlarged scape and pedicel and enormously long legs (Fig. 1E), and were presumably wingless, like their extant European and South African relatives (Jałoszyński et al., 2017a; Yin et al., 2017b). However, Upper Eocene north-European †Baltostigus Jałoszyński (Fig. 1F), currently classified in this tribe, had large, functional wings, and its body shape was conspicuously stout and small, unlike that of any other Mastigini. Some extant Mastigini show uniquely modified male genitalia, with the aedeagus so enlarged that it cannot be retracted into the male’s abdomen in repose (Jałoszyński et al., 2015). They have evolved a mating mechanism not known in any other beetles, in which one strongly elongate paramere (the other one is vestigial or obliterated) is inserted into the female’s subelytral space (Jałoszyński et al., 2015). An asymmetrical aedeagus was also found in the Upper Cretaceous †Clidicostigus, raising questions related to the unique origin of asymmetrical genitalia in the Mastigini. Finally, species of Mediterranean and Carpathian Leptomastacini are small (1.1–3 mm long) beetles, typically depigmented, flattened, microphthalmous or blind and inhabit deep soil layers (e.g. Castellini, 1996). Fossils of Leptomastacini remain unknown. Figure 1. View largeDownload slide Examples of extant and extinct Mastigitae. A, Clidicus formicarius (Borneo). B, †Cretoleptochromus archaicus (Cenomanian of Myanmar). C, †Euroleptochromus sabathi (Eocene of Lithuania). D, †Rovnoleptochromus ableptonoides (Eocene of Ukraine). E, †Clidicostigus arachnipes (Cenomanian of Myanmar). F, †Baltostigus antennatus (Eocene of Poland). B–F, artistic reconstructions based on the respective holotype specimens. Scale bars: 2 mm. Figure 1. View largeDownload slide Examples of extant and extinct Mastigitae. A, Clidicus formicarius (Borneo). B, †Cretoleptochromus archaicus (Cenomanian of Myanmar). C, †Euroleptochromus sabathi (Eocene of Lithuania). D, †Rovnoleptochromus ableptonoides (Eocene of Ukraine). E, †Clidicostigus arachnipes (Cenomanian of Myanmar). F, †Baltostigus antennatus (Eocene of Poland). B–F, artistic reconstructions based on the respective holotype specimens. Scale bars: 2 mm. The Mastigitae show a puzzling distribution, with wide geographic disjunctions within its tribes, and even within genera such as Palaeostigus Newton (Mastigini), which occurs in Southern Europe and South Africa (Fig. 2). This distribution posed puzzling biogeographic problems for previous researchers; for instance, the ‘bipolar’ western Palaearctic and southern African distribution of Mastigini was interpreted by Endrödy-Younga (1978) as evidence for Pangean origins of this tribe, and, later, Castellini (1996) suggested central Africa as the source of the present-day diversity and distribution of Mastigitae, with ancestors of Mastigini dispersing southward into South Africa, and northward into Europe during the Lower Cretaceous. The latter author entirely omitted the New World taxa from his discussion. O’Keefe (2002) carried out a phylogenetic analysis with only four genera, including one extinct species, and hypothesized a single split between Clidicini in Eurasian and American parts of Laurasia before or during the Cretaceous. This author, in turn, omitted South African taxa. Jałoszyński (2012a) included in his phylogenetic analysis nearly all genera (extant and extinct) unambiguously placed in the Mastigitae at that time, including a newly discovered Upper Eocene genus †Euroleptochromus Jałoszyński, proposed Laurasia as the ancestral area for this supertribe and explained the puzzling distribution of extant Mastigini as being the result of one of the youngest events in the biogeography of Mastigitae – a dispersal from Europe to South Africa. The subsequent discovery of another, new Upper Eocene genus, †Baltostigus Jałoszyński, placed in Mastigini, and the addition of the poorly known extant genus Taurablepton Franz, resulted in further support for the Laurasian (or Eurasian) hypothesis (Jałoszyński, 2016b). Figure 2. View largeDownload slide Distribution of Mastigitae (divided into tribes in the traditional sense). Figure 2. View largeDownload slide Distribution of Mastigitae (divided into tribes in the traditional sense). The recent accumulation of novel morphological and spatiotemporal data from newly discovered fossils of Mastigitae, allows for a new approach to the phylogeny of this interesting group. †Cretoleptochromus Cai & Huang was placed as incertae sedis and its placement requires clarification. †Cascomastigus seems to be identical with †Clidicostigus and placement of some extant genera (e.g. Papusus Casey) remained unresolved in any hitherto published phylogenetic reconstructions. Apart from newly discovered fossils, knowledge of character variability within large extant genera has recently improved considerably (e.g. Jałoszyński, 2012b; Orousset, 2014), and the previously unknown male of the enigmatic extant Turkish genus Taurablepton was discovered and made available for this study. These new data prompted us to revisit phylogenetic hypotheses of evolutionary relationships within Mastigitae, and to reconstruct ancestral character states and ancestral distribution areas. Apart from general long-standing problems, such as the currently problematic tribal classification, we also address the question of when the conspicuously asymmetrical male genitalia in Mastigini evolved. MATERIAL AND METHODS Specimen handling, imaging and measurements Species representing all genera placed unambiguously in Mastigitae were studied, including nine extant and seven extinct genera represented by 25 species. For three species, characters were extracted from original descriptions and illustrations. A list of taxa, examination methods and depositories are given in Appendix 1. Aenictosoma Schaufuss and Palaeomastigus Schaufuss, genera presumably belonging in or putatively assigned to Mastigitae, were described in an inadequate way and depositories of their type specimens remain unknown (presumably lost or destroyed during WWII); these taxa were excluded from our study. Two extant species of Clidicus Laporte were included in the analysis to represent two morphological groups within this genus, i.e. large-bodied beetles with strongly elongate antennomeres and very long maxillary palps and legs (C. formicarius), and small-bodied beetles with weakly elongate antennomeres, stout palps and relatively short legs (C. bellator); two species of Leptochromus Motschulsky were selected to represent forms with a short (L. agilis) and long (L. laselva) postgenal process; two species of Palaeostigus Newton were selected to represent the Palaearctic (P. ruficornis) and South African (P. bifoveolatus) groups. Specimens of extinct Mastigitae were studied as amber inclusions under Nikon SMZ1500 (Nikon, Tokyo, Japan) and Leica M205C (Leica Microsystems, Wetzlar, Germany) stereomicroscopes, submersed in cedar oil to improve visibility. Photographs were taken using a KYF75U digital camera (JVC, Yokohama, Japan) mounted to a Leica microscope. Image stacks were processed using COMBINEZP (Hadley, 2010). Extant taxa were studied as intact dry-mounted specimens under stereomicroscopes, as intact temporary whole-body mounts in glycerol or disarticulated permanent slides in Canada balsam under a Nikon Eclipse Ni compound microscope, or as uncoated intact specimens with a Helios Nanolab 450HP scanning electron microscope (FEI, Hillsboro, USA) (examination method for each species is given in Appendix 1). Morphological structures were figured by freehand drawing, with exact proportions and general shapes sketched from photographs. Measurement convention and the terminology of morphological structures follow those of Jałoszyński (2012a) Elytral index and pronotal index are the length of respective body part divided by its width. MicroCT imaging of amber inclusions was performed at the Department of Theoretical Biology, University of Vienna, using a Zeiss/Xradia MicroXCT-200 system with a tungsten X-ray source set at 60 kVp, with no beam filter and exposure time of 5 (Baltostigus striatipennis), 10 (Euroleptochromus setifer) or 30 s (Baltostigus antennatus) per projection. The sample was imaged at 4× (E. setifer and B. striatipennis) or 10× (B. antennatus) magnification. Image contrast benefited from propagation phase contrast in all cases. Tomographic sections were reconstructed with an isotropic voxel size of 4.0 μm (E. setifer and B. striatipennis) or 1.0 μm (B. antennatus) using the Xradia Recon software. Segmentation was accomplished in AMIRA 6.0.1 (https://www.fei.com/software/amira-for-life-sciences/), while volume rendering was performed in either AMIRA or DRISHTI 2.6.3 (https://sf.anu.edu.au/Vizlab/drishti/). The archive links for reconstructed images are as follows: http://phaidra.univie.ac.at/o:683387; http://phaidra.univie.ac.at/o:683388; and http://phaidra.univie.ac.at/o:683389. The distribution map (Fig. 2) is based on an image obtained from the Demis World Map Server open source (http://webmap.iwmi.org/DataSrc.htm). All images were edited and assembled in plates with Corel PhotoPaint 9.397. Phylogenetic analysis The analysis was based on a previously published data matrix (Jałoszyński, 2012a, 2016b), which was modified to include more characters (especially those related to genital structures and to accommodate new knowledge of the character variability within extant genera) and most recently discovered genera and species. The in-group taxa comprised representatives of all known extant and extinct genera of Mastigitae. The outgroup taxa included three genera of Scydmaenini, a tribe previously found to be the sister-group of Mastigitae (Jałoszyński, 2012c), and Euaesthetus Gravenhorst, 1806, a member of Euaesthetinae, a subfamily that, together with Steninae, forms a clade previously proposed to be the sister-group of Scydmaeninae (Grebennikov & Newton, 2009; Żyła et al., 2017). Phylogenetic analysis was based on 69 (numbered from 0) non-additive and unordered adult morphological characters; inapplicable character states were assigned a gap value (‘–’) and treated equivalent to missing data (‘?’). The data matrix was assembled in NEXUS DATA EDITOR for Windows v.0.5.0 (Page, 2001). The data matrix is presented in Appendix 2; the character list and states are given in Appendix 3. Parsimony analysis was conducted in TNT (Goloboff et al., 2008) under equal weights and using implied weighting (at the weighting function K ranging from 3 to 12) using the ‘traditional search’ strategy; the analysis was rooted with Euaesthetus. The tree bisection reconnection swapping algorithm was applied, with 1000 replicates and 1000 trees saved per replication. Standard bootstrap analysis (1000 replicates) was also conducted in TNT, and character mapping was performed in WINCLADA v.1.00.08 (Nixon, 1999–2002). Trees were exported from WINCLADA and annotated in COREL DRAW 9. The Bayesian analysis was conducted using MRBAYES v.3.2.6 (Ronquist et al., 2012) on the CIPRES Science Gateway v.3.3 (phylo.org), with four chains of two runs each. The Mkv model of character evolution was used with a gamma distribution, to allow for variation in the rate of evolution between characters, considered to be more realistic given the wide range of variability seen between morphological structures. Default settings were used, except for ‘temp = 0.05’ to improve mixing of the chains. Convergence was assessed in TRACER v.1.6.0 (Rambaut et al., 2014) and using PSRF and average standard deviation of split frequencies values in the MRBAYES output. Nodes resolved in the majority rules consensus trees with bootstrap <55 (Parsimony) or PP < 0.70 were considered unsupported. Reconstruction of ancestral character states was carried out in MESQUITE v.3.2 (Maddison & Maddison, 2017), using the 50% majority rule consensus tree obtained in the parsimony analysis under implied weights at the weighting function K = 3. This tree, as better resolved than the results of the Bayesian analysis, was chosen as representing the best available hypothesis for character and biogeographical analyses. The wing character states were not included in the dataset, as the absence or presence of wings in those fossils that do not have exposed wings is only presumed. Therefore, the evolution of winglessness was not reconstructed, but inferred on the basis of tree topologies, i.e. if an ancestral lineage split into winged and wingless taxa, we assume that the ancestor was winged, and the split was followed by loss of wings in one or more of the offspring taxa, instead of chosing an alternative hypothesis that the ancestor was wingless and the wings re-developed in some of the descendent taxa. Biogeographic reconstructions In order to reconstruct the history of biogeographic distributions of Mastigitae, statistical dispersal-vicariance (S-DIVA) analysis and Bayesian Binary Markov Chain Monte Carlo (BBM) Analysis were carried out, using the RASP program (Yu et al., 2010, 2015). The distribution of studied taxa was divided into five recent regions: Eurasia, South Africa, North America, Central and South America, and Australia. In S-DIVA, the maximum areas to each node were restricted to two; the ‘allow reconstruction’ option was switched on. In BBM, the ancestral range of the root was considered too wide to be useful and, consequently, the root distribution was set at ‘wide’ (i.e. the virtual outgroups assigned to the phylogenetic tree prior to the start of an analysis coded to occur in all areas occupied by the in-group); the JC model was selected and the default number of cycles (50000; sufficient to obtain the difference between run 1 and 2 <0.01), chains (10), frequency of samples (100), samples discarded (100) and temperature (0.1) were used. Two separate analyses were run, with two and five maximum areas allowed in ancestral distribution of each node. RESULTS Phylogeny The traditional search run of TNT under equal weights resulted in 105 most parsimonious trees; re-analysis under implied weights (at all tested weighting functions) resulted in only 15 most parsimonious trees (tree length, L = 136; consistency index, CI = 0.52; retention index, RI = 0.82); and in each of them the same six major clades within Mastigitae were resolved as in the unweighted analysis (Fig. 3, clades A–F). Differences were restricted to relationships between terminal taxa within clades B, E and F. In the 50% majority rule consensus tree (Fig. 3), some relationships within these three clades remained unresolved. Optimized apomorphies are shown on one of the shortest trees from the parsimony analysis under implied weights and K = 3.000 (Fig. 4). Figure 3. View largeDownload slide Results of the parsimony analysis of the phylogenetic relationships within Mastigitae. 50% majority rule consensus of 15 most parsimonious trees (L = 136; CI = 0.52; RI = 0.82) obtained under implied weighting and K = 3.000. The trees were rooted on Euaesthetus. Standard bootstrap support values >50 are shown above branches and ancestral areas reconstructed in S-DIVA are mapped on the tree. Figure 3. View largeDownload slide Results of the parsimony analysis of the phylogenetic relationships within Mastigitae. 50% majority rule consensus of 15 most parsimonious trees (L = 136; CI = 0.52; RI = 0.82) obtained under implied weighting and K = 3.000. The trees were rooted on Euaesthetus. Standard bootstrap support values >50 are shown above branches and ancestral areas reconstructed in S-DIVA are mapped on the tree. Figure 4. View largeDownload slide Results of the parsimony analysis of the phylogenetic relationships within Mastigitae. One of 15 most parsimonious trees with unambiguously optimized character changes plotted along the internodes. Black circles indicate unique character changes; white circles indicate parallelisms or reversals; character numbers are above circles; character states are below circles. Figure 4. View largeDownload slide Results of the parsimony analysis of the phylogenetic relationships within Mastigitae. One of 15 most parsimonious trees with unambiguously optimized character changes plotted along the internodes. Black circles indicate unique character changes; white circles indicate parallelisms or reversals; character numbers are above circles; character states are below circles. The backbone of the resultant tree (Fig. 3) is poorly supported or unsupported by bootstraps, with the entire Mastigitae (comprising clades A–F) and three consecutive nodes receiving bootstrap values <50. Each of the major clades A, B and D–F (clade C constitutes only one genus, Papusus) was supported by bootstrap values 55–99, with the lowest support for clades containing the highest number of extinct species, and consequently the highest number of missing character states (clades B, D, E and F). The multiple runs of the Bayesian analysis converged far before 10 million generations; at the end of the analysis, all PRSF values were approaching 1.000 and the average standard deviation of split frequencies reached 0.004. Clades A, B, D and E+F were resolved in Bayesian analysis (50% majority rule tree shown in Supporting Information, Figure S1), with posterior probability (PP) = 0.91–1. The Mastigitae in the Bayesian analysis were well supported by PP = 0.87, but the major clades formed an unresolved polytomy; also the three species of Baltostigus formed a polytomy with clade F of the parsimony tree. As the sister-group relationships between the major clades of Mastigitae were better resolved in the weighted parsimony analysis, its results are here presented as a phylogenetic hypothesis, with discussion of differences in relation to the Bayesian results. The monophyly of Mastigitae is supported by six apomorphies (character number and states in brackets): antennal cavities clearly separated from mandibular bases [8(1)]; labrum with anteromedian emargination [14(1)] (shared with some Scydmaenini and reversed in some Clidicus); scape at least as long as head capsule [27(1)] (in some Mastigitae scape much longer than head); posteromedian projection of anterior mesoventral ridge posteriorly demarcated from mesoventral intercoxal process [39(1)]; mesoventrite with transverse impression filled with setae [40(1)] (reversed in Mastigus and Stenomastigus); and elytral disc with punctures arranged in longitudinal rows or with impressed longitudinal striae [60(0)]. The latter character state is difficult to observe in extant Mastigini, whose elytra appear smooth or uniformly covered with microgranules. However, in each species of Mastigus, Palaeostigus and Stenomastigus, fine and shallow striae are present, best visible in the two former genera, in Stenomastigus often obscured by microsculpture. Clade A, composed of all genera traditionally placed in Leptomastacini, was placed as an unsupported sister to all remaining Mastigitae in the parsimony analysis; its placement in the Bayesian consensus tree remained unresolved. This clade was strongly supported (bootstrap = 99; PP = 1) and its components share the following nine apomorphies: thorax and antennae with modified, broadened and flattened setae [0(1)]; posterior margin of vertex with a pair of distinctly enlarged lateral setae, clearly different from surrounding setae, or with a pair of conspicuous chaetopores [7(1)] (shared only with Palaeoleptochromus); compound eyes vestigial or absent [12(1)] (shared with some Scydmaenini); maxillary palpomeres 3 and 4 together forming a compact oval with lateral margins confluent [24(0)]; vestiture of basisternal part of prosternum composed of two rows of setae extending along anterior and posterior margin [37(1)]; postmesocoxal metaventral fovea present [50(1)] (shared with Leptochromus); anterolaterally directed fovea at lateral margin of mesocoxal cavity present [51(1)] (shared with Leptochromus); mesocoxa with a ventral row of several (3–6) thick bristles conspicuously thicker than basic vestiture of coxa [54(1)] (shared with Papusus); and apices of parameres abruptly and strongly bent mesally [68(0)]. Also, all Leptomastacini are lightly pigmented, small (1.1–2.89 mm) and wingless. Fossils of this interesting, presumably subterranean, group of Scydmaeninae, remain unknown. Clidicus, †Cretoleptochromus and †Palaeoleptochromus were resolved as components of clade B, very weakly supported in the parsimony analysis by a bootstrap value of 55, but strongly supported in the Bayesian analysis by PP = 0.93. In the parsimony analysis, this clade was placed (unsupported) as sister to all Mastigitae except for Leptomastacini; in the Bayesian consensus tree, it was sister to clade D (composed of †Rovnoleptochromus, Leptochromus and †Euroleptochromus) but this position was also unsupported (PP = 0.59). Clade B is supported by the following apomorphies: some setae on frons and vertex conspicuously long and erect among much shorter and denser basic vestiture [1(1)]; at least a few remarkably long, erect and often thickened setae or thick bristles located on anteroventral surface of maxillary palpomere 2 among shorter and/or suberect or recumbent basic vestiture [17(1)] (shared with clade D); posterior pronotal collar present [33(0)] (shared with clade D); admetacoxal margin of metaventrite with an angulate expansion [53(1)] (shared with clade F and Leptochromus); and one or two conspicuously long and erect ventral setae present in basal half of profemur [57(1)]. Taxa included in this tribe are so similar to one another that they all may constitute a single genus (see Reclassification of Mastigitae section below). Papusus (clade C) in the parsimony analysis was placed in an unsupported position as sister to clades D + (E+F); placement of this problematic genus in the Bayesian consensus tree was unresolved but it was never included in clades A, B, D, F or E+F. Papusus is defined by one unique apomorphy: conspicuously large eyes that occupy half of the head length, making the tempora much shorter than eyes; in all remaining Mastigitae the eyes are small, located in the anterior portion of the head capsule and the tempora are longer than the eyes. Clade D is composed of extant Leptochromus and extinct †Rovnoleptochromus and †Euroleptochromus; it is weakly supported by a bootstrap value of 67, but well-supported in the Bayesian analysis, by PP = 0.91. In the parsimony analysis, this group was placed as an unsupported sister to the Mastigini (in the traditional sense, i.e. including †Baltostigus); in the Bayesian consensus tree, clade D was placed as an unsupported sister to clade B (i.e. Clidicus and the like). Clade D taxa share the following apomorphies: postgenal bristles present [9(1)] (shared with some members of clade B); at least a few remarkably long, erect and often thickened setae or thick bristles on anteroventral surface of maxillary palpomere 2 among shorter and/or suberect or recumbent basic vestiture [17(1)] (shared with some members of clades B and F); posterior pronotal collar [33(0)] (shared with clade B); and a unique protrochanteral ventral comb of several (2–7) thick bristles [55(1)]. Additionally, Neotropical Leptochromus also shares with European †Rovnoleptochromus and †Euroleptochromus a conspicuously similar body shape with a strongly transverse head capsule. Within clade D, both parsimonious and Bayesian results placed †Rovnoleptochromus as the sister-group of †Euroleptochromus + Leptochromus; the sister relationship between †Euroleptochromus and Leptochromus was supported by bootstrap 89, PP = 0.98, and three unique apomorphies: postgenal process present [10(1)]; setal process present on maxillary palpomere 2 [16(1)]; and profemoral ventral comb of several thick bristles present [56(1)]. All extant Mastigini, †Baltostigus, †Clidicostigus and †Cascomastigus, were resolved as a monophyletic unit in both parsimony and Bayesian analyses, weakly supported by bootstrap (63) but strongly by PP (0.99) values. Relationships within this group were poorly resolved in the Bayesian analysis; parsimony analysis resolved two moderately supported clades, E and F (bootstraps 78 and 74, respectively). In the Bayesian analysis, the clade composed of Stenomastigis, Mastigus Palaeostigus, †Clidicostigus and †Cascomastigus (= F in the parsimony tree) was strongly supported by PP = 1. Clade E is composed of all †Baltostigus species, which are known from the Eocene of Europe, and clade F includes all remaining extant and extinct Mastigini (in the traditional sense). Clade F is well-supported by nine apomorphies (four unique): frontoclypeal groove marked only at middle [4(0)] (shared with the outgroup taxa and Leptomastacini); median longitudinal groove on vertex present [5(1)]; eyes adjacent to antennal insertions [13(0)] (shared only with Scydmaenus); mesoventral intercoxal process stout, about as long as broad [42(1)]; lateral margins of mesoventral intercoxal process between mesocoxae convergent posteriorly [44(1)] (shared with the outgroup, Leptomastacini and †Rovnoleptochromus); metaventrite broadest at or just in front of metacoxae [47(1)]; admetacoxal margin of metaventrite with angulate expansion [53(1)] (shared with clade B and Leptochromus); suture between metaventrite and first visible abdominal sternite nearly obliterated, abdominal sternite medially fused with posterior margin of metaventrite [58(1)]; and parameres asymmetrical, one paramere shorter than the other [67(1)] (possibly shared with some †Cretoleptochromus, but variable also within extant Clidicus; character state not known for †Cascomastigus monstrabilis). Clade E, composed of †Baltostigus, shares most synapomorphies with its sister-group, i.e. clade F, and is supported by an absent posteromedian impression on vertex [6(0)], maxillary palpomere 3 with sparse, long and strongly erect setae present among basic recumbent or suberect vestiture [18(1)] (shared with some members of clade B) and a strongly broadened maxillary palpomere 4 [22(1)]. Ancestral character states Reconstruction of ancestral character states was carried out in accordance with the phylogenetic hypothesis adopted here (Fig. 3). Character states reconstructed for the ancestor of Mastigitae are listed in Supporting Information, Appendix S1. Taxonomically, the most important character states of this hypothetical ancestor are: the vertex lacking median longitudinal groove [5(0)] and posteromedian impression [6(0)]; posterior margin of vertex lacking a pair of enlarged setae [7(0)]; head capsule unmodified, lacking postgenal bristles [9(0)] and postgenal process [10(0)], but with large compound eyes [12(0)]; labrum with anteromedian emargination [14(1)]; maxillary palpomeres 2 and 3 lacking modifications and covered with setae of uniform length [16(0], [17(0)], [18(0)]; maxillary palpomere 4 narrower than 3 [20(1)] and narrowing from base to apex [21(0)]; scape as long as head or longer [27(1)], lacking bristles [30(0)]; pedicel short and lacking bristles [29(0)]; antennae capable of bending ventrally or ventrolaterally between scape and pedicel [28(2)]; pronotum lacking posterior collar [33(1)]; mesoventral intercoxal process slender and narrow [42(0)]; posterior margin of mesocoxal cavities carinate [46(0)]; mesocoxae, protrochanters and profemora lacking thick bristles [54(0)], [55(0)], [56(0)]; elytra with rows of punctures or longitudinal striae [60(0)] and lacking basal foveae [62(0)]. The reconstruction of genital characters, although possible only to a limited extent due to incompleteness of data related to fossils, gave the following results: abdominal sternite 8 in males unmodified, rounded or truncate posteriorly [64(1)]; flagellum straight or C-shaped, not looped [65(0)]; copulatory piece not permanently everted [66(0)]; parameres symmetrical or nearly symmetrical [67(0)], with apices not abruptly bent mesally [68(1)]. Ancestral distribution areas Optimization of the ancestral distributions on the consensus phylogenetic trees using the S-DIVA analysis resulted in a nearly unambiguous reconstruction (Fig. 3; complete results given in Supporting Information, Appendix S2). The supertribe Mastigitae appears to have originated in the Eurasian part of Laurasia, with subsequent dispersals to the North American part of Laurasia (†Palaeoleptochromus), Australia (Clidicus) and South Africa (Palaeostigus), and origination of Papusini + (Leptochromini + (†Baltostigini + Mastigini)) in Laurasia. Clades of eastern Laurasian (Eurasian) origins are Clidicini + (Papusini + (Leptochromini + (†Baltostigini + Mastigini))); Leptochromini + (†Baltostigini + Mastigini); and †Baltostigini + Mastigini. Results of the Bayesian BBM analysis were more ambiguous (Supporting Information, Appendix S2). In the analysis with two ancestral areas allowed for each node, the most probable scenarios were: †Baltostigini + Mastigini originated in the Eurasian part of Laurasia (83.08%); Leptochromini + (†Baltostigini + Mastigini) in the Eurasian + North American parts of Laurasia (66.90%); Papusini + (Leptochromini + (†Baltostigini + Mastigini)) in Eurasian + North American parts of Laurasia (66.44%); Clidicini + (Papusini + (Leptochromini + (†Baltostigini + Mastigini))) in Eurasian + North American parts of Laurasia (86.15%); and Mastigitae in Eurasian + North American parts of Laurasia (65.70%). Increasing the allowed ancestral areas for each node to five resulted in the same scenarios for most of the clades: †Baltostigini + Mastigini originated in Eurasian part of Laurasia (84.13%); Leptochromini + (†Baltostigini + Mastigini) in Eurasian + North American parts of Laurasia (57.08%); Papusini + (Leptochromini + (†Baltostigini + Mastigini)) in Eurasian + North American parts of Laurasia (66.35%); Clidicini + (Papusini + (Leptochromini + (†Baltostigini + Mastigini))) in Eurasian + North American parts of Laurasia + Australia (45.55%); and Mastigitae in Eurasian + North American parts of Laurasia + Australia (27.36%). TAXONOMY Staphylinidae Latreille, 1802 Scydmaeninae Leach, 1815 Mastigitae Fleming, 1821 Clidicini Casey, 1897 sensu nov. Type genus: Clidicus Laporte, 1832. Diagnosis Clidicini, restricted here to Clidicus and †Palaeoleptochromus (which may be a synonym of the former), are defined by the following unique apomorphies: some setae on frons and vertex conspicuously long and erect among much shorter and denser basic vestiture, and one or two conspicuously long and erect ventral setae present in basal half of profemur; and a set of synapomorphies (known in other tribes, but in a different combination): only scape enlarged and longer than head; head capsule about as long as broad or slightly transverse; antennal insertions broadly separated; occipital constriction about half as broad as width of head or narrower; eyes small, much shorter than tempora; maxillary palpomere 4 subtriangular; pronotum with posterior collar separated by transverse row of pits; mesoventral intercoxal process narrow, carinate, with subparallel lateral margins; admetacoxal margin of metaventrite with an angulate expansion; elytral rows of punctures distinct; abdominal sternite 6 not emarginate. Clidicus Laporte, 1832 = †Cretoleptochromus Cai & Huang, 2016 syn. nov. Remarks Clidicus comprises 27 species distributed in Sri Lanka, southern India, South-East Asia, Hainan Island, and north-eastern Australia (Orousset, 2014). Recently Cai & Huang (2016) described a new genus and species †Cretoleptochromus archaicus (Figs 5A–F, 6A, B) and placed it as incertae sedis within Mastigitae; later Yin et al. (2017) added †Cretoleptochromus burmiticus to this enigmatic genus. Both species are known from Cenomanian amber of Myanmar. Both of them, and especially †C. burmiticus, are remarkably similar to extant species of the morphologically diverse genus Clidicus. †Cretoleptochromus was compared to Clidicus by Cai & Huang (2016) and found to differ from the latter in (cited verbatim) ‘elongate maxillary palpomeres III and IV (not enlarged), elongate pronotum, and slender legs’. Indeed, in some species of Clidicus (e.g. C. bellator, C. rufescens Jałoszyński et al. and others) palpomere 3 is only ∼1.5 times as long as broad, and palpomere 4 is hardly longer than broad (Fig. 6H). However, in many species the palpomeres are elongate nearly as much as those in †Cretoleptochromus, e.g. in Clidicus formicarius (Fig. 6I). The palpomeres in Clidicus and Cretoleptochromus apparently form a morphocline, gradually changing from stout to strongly elongate (Fig. 6A, C–E, G–I). Moreover, within Clidicus, the length of maxillary palps in relation to the head capsule is also highly variable, as demonstrated by examples in Figure 6G–I. Cretoleptochromus represents merely the most elongate variant within the Clidicus morphocline. Its mouthparts (Fig. 6B) do not differ from those of any extant Clidicus (Fig. 6F). An elongate pronotum cannot be used to distinguish †Cretoleptochromus from Clidicus, either. The pronotum in †Cretoleptochromus archaicus (Fig. 5A, B) is only slightly elongate, ∼1.2× as long as broad. The shape and proportions of the pronotum vary considerably among Clidicus, from stout, slightly broader than long (e.g. Clidicus aliquantulus Jałoszyński et al., C. rufescens, C. ganglbaueri Reitter and C. minutus Orousset) to distinctly elongate, 1.2× or slightly more as long as broad (e.g. C. gracilipes Orousset, C. formicarius, C. tonkinensis Lhoste and others). Certainly, slender legs cannot be used to distinguish †Cretoleptochromus from Clidicus, as the length of legs in relation to the body is highly variable and changes gradually in Clidicus species. In extant species of the latter, forms with relatively short (e.g. C. bellator) and extremely long legs (e.g. C. formicarius) can be found. Moreover, legs in Clidicus formicarius (Fig. 1A) are in fact slightly more elongate than those in †Cretoleptochromus archaicus (Fig. 1B). Figure 5. View largeDownload slide Holotype of †Cretoleptochromus archaicus (Cenomanian of Myanmar). A, B, head and prothorax in dorsal view. C, head and prothorax in ventral view. D, head in ventral view. E, F, pterothorax and abdomen in ventral view. Characters and character states (listed in Appendix 3) indicated by arrows. Scale bars: 1 mm. Figure 5. View largeDownload slide Holotype of †Cretoleptochromus archaicus (Cenomanian of Myanmar). A, B, head and prothorax in dorsal view. C, head and prothorax in ventral view. D, head in ventral view. E, F, pterothorax and abdomen in ventral view. Characters and character states (listed in Appendix 3) indicated by arrows. Scale bars: 1 mm. Figure 6. View largeDownload slide Comparison of †Cretoleptochromus (A–E) with extant species of Clidicus (F–I). A, †Cretoleptochromus archaicus, right antenna and maxillary palp in dorsal view. B, †Cretoleptochromus archaicus, mouthparts in ventral view. C–E, †Cretoleptochromus sp. (AMNH Bu-SY17), maxillary palp in anterior, C, D, and dorsal, E, views. F, Clidicus formicarius (Borneo), mouthparts in ventral view. G, Clidicus abbotensis (Australia), head in ventral view. H, Clidicus bellator (Vietnam), head in dorsal view. I, Clidicus formicarius, head in dorsal view. Characters and character states (listed in Appendix 3) indicated by arrows. Abbreviations: bst, basistipes; cd, cardo; lp2–3, labial palpomere 2–3; md, mandible; mst, mediostipes; mxp 1–4, maxillary palpomere 1–4; pd, pedicel; prm, prementum; sc, scape. Scale bars: 0.5 mm. Figure 6. View largeDownload slide Comparison of †Cretoleptochromus (A–E) with extant species of Clidicus (F–I). A, †Cretoleptochromus archaicus, right antenna and maxillary palp in dorsal view. B, †Cretoleptochromus archaicus, mouthparts in ventral view. C–E, †Cretoleptochromus sp. (AMNH Bu-SY17), maxillary palp in anterior, C, D, and dorsal, E, views. F, Clidicus formicarius (Borneo), mouthparts in ventral view. G, Clidicus abbotensis (Australia), head in ventral view. H, Clidicus bellator (Vietnam), head in dorsal view. I, Clidicus formicarius, head in dorsal view. Characters and character states (listed in Appendix 3) indicated by arrows. Abbreviations: bst, basistipes; cd, cardo; lp2–3, labial palpomere 2–3; md, mandible; mst, mediostipes; mxp 1–4, maxillary palpomere 1–4; pd, pedicel; prm, prementum; sc, scape. Scale bars: 0.5 mm. Examination of the holotype of †Cretoleptochromus archaicus revealed a character overlooked by Cai & Huang (2016): a median longitudinal carina of the metaventrite (Fig. 5F). Such a carina was known only in Ablepton and †Rovnoleptochromus. This is an interesting structure, not known in †Cretoleptochromus burmiticus nor any extant species of Clidicus. Such a carina does not occur in an undescribed species identified here as closely resembling †Cretoleptochromus burmiticus, also in Cenomanian Myanmar amber (specimen AMNH Bu-SY17; Supporting Information, Figs S2, S3). Considering the presence and absence of this carina among Cenomanian Cretoleptochromus, it must be regarded as a character variable within this genus, and cannot be used to distinguish †Cretoleptochromus from Clidicus. The length of the maxillary palps in relation to the head, width and relative lengths of maxillary palpomeres (Fig. 6G–I), antennomeres (Fig. 6H, I) and distribution of conspicuously long, erect setae on the head capsule and maxillary palpomeres (Fig. 6G–I) are variable within extant species of Clidicus; also the shape and proportions of the head, pronotum and elytra, and even the shape of the labrum (Orousset, 2014) vary among extant species of this genus, and cannot serve as diagnostic characters to distinguish Cretoleptochromus from Clidicus. Moreover, we report here for the first time a definitive Clidicus species from the Eocene of Russia (Kaliningrad, CCHH 1543-1; Supporting Information, Figs S4, S5), preserved as an inclusion in Baltic amber. This species cannot be formally described due to poor visibility of crucial structures; it is largely covered with air bubbles. However, its general body shape and visible structures of the head, palps, mandibles, antennae, pronotum, elytra and legs are strikingly similar to those of extant middle-sized (5–6 mm) species of Clidicus, e.g. C. crocodylus Jałoszyński. The Eocene specimen has strongly elongate and relatively slender maxillary palps, with palpomere 4 of intermediate length between †Cretoleptochromus archaicus and the slender forms of extant Clidicus. Moreover, maxillary palpomeres of this species bear sparse, conspicuously long, erect setae, known in the Cenomanian †Cretoleptochromus and the slender and large extant species of Clidicus. This specimen supports our hypothesis that Clidicus has evolved in the south-eastern part of Laurasia, where it still occurs today (i.e. in SE Asia), and became widespread within eastern Laurasia, surviving in present-day north-central Europe at least until the Priabonian, presumably until the Eocene–Oligocene climate cooling. Consequently, Clidicus, treated here as a senior synonym of †Cretoleptochromus, is the first Mastigitae genus, whose evolution and distribution are documented from the Cenomanian through the Eocene up through today. †Palaeoleptochromus O’Keefe, 1997 Remarks †Palaeoleptochromus, with its sole species †P. schaufussi from the Campanian of Canada, is the most problematic extinct taxon of Mastigitae. Most characters crucial to place it in a taxonomic context are not observable in the specimen. In our analysis it was placed within the poorly resolved Clidicini sensu nov. (Fig. 3). †Palaeoleptochromus may be a junior synonym of Clidicus, and as the only North American member of this lineage, represents the only firm evidence for a broad distribution of Clidicini during the Upper Cretaceous. However, the fossil has an intriguing character, not known in any remaining Clidicini – a pair of enlarged setae on the posterior margin of the vertex (illustrated in O’Keefe et al., 1997). The placement of †Palaeoleptochromus is still unclear, so we retain this name as valid, pending further study. Papusini Jałoszyński & Brunke trib. nov. urn:lsid:zoobank.org:act:9346A6D8-168A-4FAD-8491-7D7152B6D7BE Type genus: Papusus Casey, 1897, here designated. Diagnosis Papusini differs from all remaining Mastigitae genera by the unique, very large compound eyes located at the middle, or slightly behind the middle, of the head capsule, and a set of synapomorphies known (in different combinations) in other tribes: scape about as long as head, lacking bristles; pedicel not enlarged; maxillary palpomere 3 strongly elongate, with its apical margin nearly perpendicular to the long axis of palpomere, gradually broadening distally; maxillary palpomere 4 subtriangular, broadest at base, much shorter than 3 and distinctly narrower than 3 at apex; vertex and frons lacking median longitudinal groove; posterior margin of vertex lacking a pair of modified setae or large chaetopores; pronotum lacking posterior collar; mesoventral intercoxal process elongate, slender and parallel-sided; posterior margins of mesocoxal cavities carinate; mesocoxa with longitudinal row of several (typically 5) long and thick bristles; admetacoxal margin of metaventrite at each side with indistinct expansion (i.e. not evenly concave but slightly angulate near the mesal third of metacoxa); elytra with longitudinal rows of shallow punctures; aedeagus symmetrical, with slender parameres and straight flagellum. Remarks The placement of Papusus has been problematic for the past 120 years. Casey (1897) placed it in Clidicini, based on a similar form of the maxillary palpomere 4 of Papusus to that of Clidicus. Franz (1985) transferred Papusus to Scydmaenini of Scydmaenitae, but later synonymized it under Leptochromus, automatically moving it back to Clidicini. Papusus was resurrected as a valid name and separate genus by O’Keefe (1998), who carried out a phylogenetic analysis focused on resolving relationships between species of Papusus, but used only Leptochromus as the outgroup. Later, O’Keefe (2002) proposed a sister-group relationship between Papusus and (†Palaeoleptochromus + Leptochromus), but his analysis was restricted to three genera only, with Clidicus as the outgroup. A broader taxon sampling was done by Jałoszyński (2012a, 2016b), who included all genera of Mastigitae known at that time and obtained ambiguous results concerning the placement of Papusus. It was placed, with equal parsimony, as (1) a sister-group to all remaining Clidicini (in a broad, traditional sense) vs. (2) sister to Leptomastacini + all remaining Clidicini (Jałoszyński, 2012a), or as (3) sister to Leptomastacini vs. (4) sister to a clade Clidicus + (remaining Clidicini + Mastigini) (Jałoszyński, 2016b). Consequently, Papusus remained the most problematic of all extant genera and its placement was unclear. Papusus was not placed together with the remaining genera traditionally placed in Clidicini in our phylogenetic reconstructions (neither in parsimony nor in Bayesian analyses), and although its relationships within Mastigitae are still far from being solved, it is clear that Papusus cannot be maintained as a member of Clidicini, based on: the emarginate male sternite 8; the absence of a pronotal collar; uniform setae on frons, vertex and maxillary palpomere 2; narrowly separated antennal cavities; and the presence of a row of mesocoxal bristles. Leptochromini Jałoszyński & Brunke trib. nov. urn:lsid:zoobank.org:act:C45F0203-7DB9-40D2-8B60-6929C30A0FC9 Type genus: Leptochromus Motschulsky, 1855, here designated. Diagnosis Leptochromini differs from all remaining Mastigitae in a unique apomorphy: protrochanteral ventral comb of several (2–7) thick bristles; postgenal bristles are also most likely an autapomorphy of Leptochromini (see Remarks below); and a set of synapomorphies shared with members of other tribes (but in different combinations): scape longer than head, lacking bristles; pedicel unmodified; head capsule strongly transverse; maxillary palpomeres 2 and 3 strongly elongate, palpomere 4 shorter than 3, variable in shape, suboval, subtriangular or nearly rod-like; pronotum with distinct posterior collar; elytra with distinct rows of punctures; mesoventral intercoxal process narrow and elongate, subparallel or slightly narrowing posteriorly; abdominal sternite 8 in males emarginate at middle (this character state remains unstudied in fossils); aedeagus symmetrical or nearly symmetrical, with straight flagellum (also not known in fossils). Remarks Postgenal bristles in our analyses were coded assuming their homology in members of the newly defined tribe Leptochromini and Clidicus formicarius, †Palaeoleptochromus schaufussi, †Cretoleptochromus archaicus and †Cretoleptochromus burmiticus. The previous placement of all these genera (except †Cretoleptochromus treated as incertae sedis) in Clidicini suggested such a homology, with thick postgenal bristles of Leptochromus, †Euroleptochromus and †Rovnoleptochromus presumably developed from sparse and conspicuously long, erect setae present in the same area in some species of the Clidicus/† Cretoleptochromus/†Palaeoleptochromus lineage. However, the topology obtained in our parsimony analysis and reconstruction of ancestral character states falsified this hypothesis, in favour of a parallelism, i.e. an independent evolution of long setae and bristles in Clidicini sensu nov. and Leptochromini. Whether Leptochromini represents the sister-group of †Baltostigini + Mastigini (resolved but unsupported in parsimony analysis) or Clidicini (as found in the Bayesian analysis, but without support, PP = 0.59) remains an unsettled issue. However, the genera placed in Leptochromini form a monophyletic morphological unit in topologies obtained in both analyses, and for this reason they are placed in a separate tribe. Defined as above, Leptochromini differs from Clidicini sensu nov. in the presence of a protrochanteral ventral comb of thick bristles; presence of postgenal bristles (conspicuously thicker than long setae in Clidicini); maxillary palpomere 4 slightly broadening distad, at least in basal half; and abdominal sternite 8 in males emarginate at middle (but not known in fossils). Moreover, the strongly transverse head capsule in Leptochromini (Fig. 1C, D) clearly differs from the subrectangular or subtrapezoidal and weakly transverse head of Clidicini (Fig. 1A, B). †Euroleptochromus Jałoszyński, 2012 †Euroleptochromus setifer Jałoszyński & Brunke sp. nov. (Fig. 7A–J) urn:lsid:zoobank.org:act:9209EBD8-D459-46E8-9108-7BC08F2E55CE Type material Holotype (CCHH 835-3), from Baltic amber (Russia, Kaliningrad); female (confirmed by μCT scan of postabdomen), preserved in a rectangular prism (7 × 6 × 3.5 mm) of amber (CCHH/SDEI). Diagnosis Protrochanter of female subtriangular, with apical bristle and single apical seta as long as trochanter; elytral index <1.7; pronotum strongly elongate, pronotal index nearly 1.3; scape nearly 3.7 times as long as pedicel, each of antennomeres 4–7 at least 1.25× as long as scape. Description Body (Fig. 7A, E–G) slender, length 3.08 mm, dark brown. Head (Fig. 7B, H, I) strongly transverse, length 0.45 mm, width 0.58 mm; occipital constriction (Fig. 7I) about half as wide as width of head, vertex strongly transverse, indistinctly impressed medially and anteriorly confluent with strongly transverse frons; eyes large and strongly projecting from the silhouette of the head; postgenal process (Fig. 7B, E, F, I) nearly 3× as long as broad, with two long and divergent apical bristles. Submentum (Fig. 7I) strongly transverse, demarcated laterally by weakly sinuate and complete hypostomal ridges. Maxillary palp (Fig. 7B, I) much longer than head, palpomere 2 much longer than 3 but shorter than 3 and 4 combined, divided by angulate expansion located in proximal 0.4 into two unequal parts, proximal part distinctly curved, distal part nearly straight and slightly broader, angulate expansion with one robust anterior bristle; palpomere 3 slender, nearly cylindrical in basal half and then gradually broadening distad; palpomere 4 as long as 0.35 of palpomere 3, suboval. Punctures and setae on frons and vertex fine, inconspicuous. Antennae much shorter than body, length 2.26 mm, relative lengths of antennomeres (the shortest antennomere 3 as 1): 4: 1.09: 1.00: 1.45: 1.45: 1.36: 1.36: 1.27: 1.09: 1.09: 1.27. Antennomeres sparsely covered with suberect setae of various lengths. Pronotum (Fig. 7D, E, G) elongate and broadest distinctly in front of middle, length 0.88 mm, width 0.68 mm, pronotal index 1.29; disc convex and sparsely covered with shallow but distinct punctures (those near middle separated by spaces 2–3 times as wide as diameters of punctures), setae indiscernible; posterior collar demarcated by transverse row of four dorsal pits, additionally one laterodorsal pit located at each side of pronotum; posterior pronotal margin with narrow groove. Prosternum (Fig. 7F) with basisternal part about as long as procoxae, lacking discernible traces of notosternal sutures, procoxae contiguous. Mesoventral intercoxal process (Fig. 7J) carinate, parallel-sided, weakly elevated. Metaventrite (Fig. 7F) slightly impressed posteromedially, metacoxae broadly separated. Elytra (Fig. 7E, G) strongly convex, broadest near middle, length 1.75 mm, width 1.08 mm, elytral index 1.63; each elytron with four dorsal and two lateral rows of distinct, large punctures; humeral calli prominent, elongate; elytra sparsely covered with short suberect setae. Legs (Fig. 7A, C, E, F) long and slender, protrochanters (Fig. 7A, C) elongate and subtriangular, each with moderately long apical spine, extremely long, thin apical seta and 3–4 moderately long, thin subapical setae; profemur (Fig. 7C) with four long ventral spines, insertions of the first two spines touching each other, additionally profemur with several long and thin ventral setae; protibiae strongly curved; remaining legs unmodified. Etymology The name setifer (treated here as a noun in apposition) refers to the unusually long seta on each protrochanter. Type locality and horizon Russia, Kaliningrad; Upper Eocene. Remarks Apart from the female trochanter, this species differs from the previously known †E. sabathi in the elytral index 1.63 (1.74 in †E. sabathi), a much more elongate pronotum (pronotal index 1.29 vs. 1.00 in †E. sabathi), the scape 3.67 times as long as pedicel (only 2.94 times in †E. sabathi) and each of antennomeres 4–7 at least 1.25 times as long as scape (0.94–1.06 times in †E. sabathi). In all other characters these two upper Eocene species are very similar. Results of the μCT scan of †E. setifer demonstrated for the first time that strongly curved protibiae in †Euroleptochromus are not male secondary sexual characters, but occur in females (no traces of the aedeagus were found inside the abdomen). This interesting character is, therefore, the same as in the extant and closely related Leptochromus, in which males and females have curved protibiae, and unlike extinct and extant Mastigini, where this character state is restricted to males of some species. Moreover, the μCT technique revealed structures impossible to observe in the inclusion under light microscopy, e.g. the shape of the hypostomal ridges (Fig. 7I) or the intermesocoxal region of the mesoventrite (Fig. 7J). Figure 7. View largeDownload slide Female holotype of †Euroleptochromus setifer sp. nov. (CCHH 835-3; Upper Eocene of Russia); photographs, A–D, and μCT reconstructions, E–J. A, lateroventral habitus. B, head in lateroventral view. C, left foreleg in lateral view. D, pronotum in dorsal view. E, lateral habitus. F, ventral habitus. G, dorsal habitus. H, head in dorsal view. I, head in ventral view. J, intercoxal region of pro- and mesothorax in ventral view. Characters and character states (listed in Appendix 3) indicated by arrows. Scale bars: A, E–G: 1 mm; B–D, H–J: 0.5 mm. Figure 7. View largeDownload slide Female holotype of †Euroleptochromus setifer sp. nov. (CCHH 835-3; Upper Eocene of Russia); photographs, A–D, and μCT reconstructions, E–J. A, lateroventral habitus. B, head in lateroventral view. C, left foreleg in lateral view. D, pronotum in dorsal view. E, lateral habitus. F, ventral habitus. G, dorsal habitus. H, head in dorsal view. I, head in ventral view. J, intercoxal region of pro- and mesothorax in ventral view. Characters and character states (listed in Appendix 3) indicated by arrows. Scale bars: A, E–G: 1 mm; B–D, H–J: 0.5 mm. A very similar specimen (CCHH 835-2, deposited in CCHH/SDEI; Supporting Information, Fig. S6) from the same deposit of Baltic amber (Russian, Kaliningrad) was also studied. It shows some of the diagnostic characters of †E. setifer, i.e. the subtriangular protrochanter with an extremely long apical seta, but it is slightly larger (body length 3.23 mm) and has slightly different proportions of antennomeres, especially the longer scape (4.14× as long as pedicel versus 3.67× in †E. setifer). This inclusion may represent a separate species, but the opaque, milky amber obscuring the body surface, the position of the beetle inside the amber piece and the partly air-exposed surface make it difficult to measure widths of the pronotum and elytra, important for the diagnosis. This specimen does not add any novel characters to the diagnosis of †Euroleptochromus, but demonstrates a considerable variability in the relative length of the scape and pedicel within the genus. All these fossils (i.e. the holotypes of †E. sabathi, †E. setifer and specimen CCHH 835-2), as well as †Rovnoleptochromus, have prominent humeral calli (well-visible in Fig. 7E), typical of winged beetles, but hind wings are not observable in any of them. Their closest living relatives, species of Leptochromus, have similarly large and well-defined humeral calli and are winged, suggesting that Eocene species of Leptochromini were capable of flight. Baltostigini Jałoszyński & Brunke trib. nov. urn:lsid:zoobank.org:act:9C6CEA79-52A6-481D-A042-FF6D8EE53086 Type genus: Baltostigus Jałoszyński, 2016, here designated. Diagnosis Baltostigini differ from all remaining tribes in a unique combination of synapomorphies: maxillary palpomere 3 subtriangular, gradually broadening distally; palpomere 4 axe-shaped, broader than long and broadening distally; both scape and pedicel enlarged and bearing ventral spines; head capsule elongate; vertex evenly convex, not impressed posteromedially and lacking median longitudinal groove; pronotum lacking posterior collar; elytra with rows of punctures at least in anterior half; wings developed; mesoventral intercoxal process carinate and parallel-sided; aedeagus symmetrical, with both parameres equally well-developed. Remarks †Baltostigini, represented only by the Upper Eocene †Baltostigus distributed in north-central Europe, is a group closely related to Mastigini and was previously included in the latter tribe (Jałoszyński, 2016b). Placement of †Baltostigus in a separate tribe is supported by its plesiomorphic characters, not known in any Mastigini (including all extant species and the Cenomanian †Clidicostigus): fully developed wings (Fig. 8A, E) and associated elytral structures (i.e. prominent humeral calli), fully symmetrical aedeagus (Fig. 9C–E), with both parameres well-developed and equally long, and abdominal sternite 8 in males not emarginate. †Baltostigini is an extinct and early diverging group of the ancestral lineage that gave rise to Mastigini. Leptomastacini, Papusini, most Clidicini and Leptochromini have the aedeagi symmetrical or nearly symmetrical (examples are shown in Fig. 9H–P), with two long parameres; the aedeagus in Leptomastacini is twisted in repose (Fig. 9H), similar to that of Mastigini (illustrated by Jałoszyński et al., 2015), that of Clidicini, Papusini and Leptochromini is positioned symmetrically inside the abdomen, with the basal orifice facing dorsad. The symmetrical aedeagus with two long parameres (although in some cases partially fused to the lateral walls of the median lobe) is typical of Scydmaenini, the sister-group of Mastigitae, and can be regarded as the plesiomorphic condition for Mastigitae. †Baltostigini are characterized by this plesiomorphic condition, the aedeagus of †Baltostigus (Fig. 9B–E) is not only symmetrical with two long parameres, but also symmetrically positioned in repose, with its basal orifice facing dorsad. All Mastigini (Fig. 9Q–U), including the Cenomanian †Clidicostigus, have the aedeagus strongly and uniquely transformed, with one paramere much longer than the other; in most ‘advanced’ extant forms one paramere is entirely obliterated and the long one monstrously enlarged (Fig. 9T, U). Based on genital characters and ancestral character state reconstructions, we postulate an early (Cenomanian or earlier) split between †Baltostigus and the ‘asymmetrical’ ancestor of Mastigini (see Discussion). Figure 8. View largeDownload slide Female holotype of †Baltostigus striatipennis sp. nov. (AMNH Bu-SY18; Upper Eocene of Russia); photographs, A–D, line drawings, E–H, and μCT reconstructions, J, K. A, anterodorsal habitus. B, head in laterodorsal and pronotum in dorsal views. C, anterior half of elytra in dorsal view. D, head in anterodorsal view. E, anterodorsal habitus. F, oblique habitus. G, head in anterodorsal view. H, head in laterodorsal and pronotum in dorsal view. J, dorsal habitus. K, pterothorax and abdomen in ventral view. Characters and character states (listed in Appendix 3) indicated by arrows. Scale bars: A, B, D–G, J, K: 1 mm; C, H, I: 0.5 mm. Figure 8. View largeDownload slide Female holotype of †Baltostigus striatipennis sp. nov. (AMNH Bu-SY18; Upper Eocene of Russia); photographs, A–D, line drawings, E–H, and μCT reconstructions, J, K. A, anterodorsal habitus. B, head in laterodorsal and pronotum in dorsal views. C, anterior half of elytra in dorsal view. D, head in anterodorsal view. E, anterodorsal habitus. F, oblique habitus. G, head in anterodorsal view. H, head in laterodorsal and pronotum in dorsal view. J, dorsal habitus. K, pterothorax and abdomen in ventral view. Characters and character states (listed in Appendix 3) indicated by arrows. Scale bars: A, B, D–G, J, K: 1 mm; C, H, I: 0.5 mm. Figure 9. View largeDownload slide Postabdomen of †Baltostigus antennatus (Upper Eocene of Poland) reconstructed by μCT, A–G, and aedeagi of Mastigitae, H–U. A, posterior portion of abdomen and elytra in lateral view. B, terminal abdominal segments and aedeagus in dorsal view. C–E, aedeagus in dorsal, C, ventral, D, and lateral, E, views. F–G, terminal abdominal segments in ventral, F, and dorsal, G, views. H, posterior portion of abdomen of Ablepton treforti (Romania), showing twisted aedeagus in retracted position within. I–U, aedeagus in abparameral view. I, Ablepton treforti. J, Leptomastax stussineri (Bulgaria). K, Taurablepton sp. (Turkey). L, Clidicus aliquantulus (Vietnam). M, Clidicus gracilipes Orousset (Sumatra). N, Leptochromus agilis (Costa Rica). O, Leptochromus laselva (Costa Rica) showing extruded flagellum. P, Papusus macer (USA). Q, Mastigus spinicornis (RSA). R, apical portion, †Clidicostigus arachnipes (Cenomanian of Myanmar), reconstructed by μCT (after Jałoszyński et al. 2017a). S, Palaeostigus tenuis (Leleup) (RSA). T, aedeagus of Stenomastigus vulgaris (Lhoste) (RSA). U, Stenomastigus longicornis Boheman (RSA). Characters and character states (listed in Appendix 3) indicated by arrows. Abbreviations: aed, aedeagus; apo9, apodeme of tergite 9; bc, basal capsule; bo, basal orifice; cp, copulatory piece; el, elytron; end, permanently extruded endophallus; fl, flagellum; ht9, hemitergite 9; ml, median lobe; pm, paramere; st8, sternite 8; st9, sternite 9; t10, tergite 10. Scale bars: 0.25 mm; Figures H–U not to the same scale. Figure 9. View largeDownload slide Postabdomen of †Baltostigus antennatus (Upper Eocene of Poland) reconstructed by μCT, A–G, and aedeagi of Mastigitae, H–U. A, posterior portion of abdomen and elytra in lateral view. B, terminal abdominal segments and aedeagus in dorsal view. C–E, aedeagus in dorsal, C, ventral, D, and lateral, E, views. F–G, terminal abdominal segments in ventral, F, and dorsal, G, views. H, posterior portion of abdomen of Ablepton treforti (Romania), showing twisted aedeagus in retracted position within. I–U, aedeagus in abparameral view. I, Ablepton treforti. J, Leptomastax stussineri (Bulgaria). K, Taurablepton sp. (Turkey). L, Clidicus aliquantulus (Vietnam). M, Clidicus gracilipes Orousset (Sumatra). N, Leptochromus agilis (Costa Rica). O, Leptochromus laselva (Costa Rica) showing extruded flagellum. P, Papusus macer (USA). Q, Mastigus spinicornis (RSA). R, apical portion, †Clidicostigus arachnipes (Cenomanian of Myanmar), reconstructed by μCT (after Jałoszyński et al. 2017a). S, Palaeostigus tenuis (Leleup) (RSA). T, aedeagus of Stenomastigus vulgaris (Lhoste) (RSA). U, Stenomastigus longicornis Boheman (RSA). Characters and character states (listed in Appendix 3) indicated by arrows. Abbreviations: aed, aedeagus; apo9, apodeme of tergite 9; bc, basal capsule; bo, basal orifice; cp, copulatory piece; el, elytron; end, permanently extruded endophallus; fl, flagellum; ht9, hemitergite 9; ml, median lobe; pm, paramere; st8, sternite 8; st9, sternite 9; t10, tergite 10. Scale bars: 0.25 mm; Figures H–U not to the same scale. †Baltostigus preserved another character state that is ancestral for the clade †Baltostigus + Mastigini, i.e. the deep elytral punctures arranged in longitudinal rows (best visible in the new species described below, and only partly developed in two previously described species; see Fig. 1F). Among Mastigini, this character state can be found only in the ancient, extinct Cenomanian †Clidicostigus (Fig. 1E), whereas the genera that survived until the present day (i.e. Mastigus, Palaeostigus and Stenomastigus) have only weakly marked, fine and often indistinct vestigial elytral rows or striae. †Baltostigus Jałoszyński, 2016 †Baltostigus striatipennis Jałoszyński, Brunke & Yamamoto sp. nov. (Figs 8A–K; Supporting Information, Figs S7, S8) urn:lsid:zoobank.org:act:72B35B19-F014-4BF9-B29C-8B7728B7ED56 Type material Holotype (AMNH Bu-SY18), from Baltic amber (Russia, Kaliningrad); female (confirmed by μCT scan of postabdomen), preserved in a slightly irregular prism (14 × 12 × 5 mm) of amber (AMNH). Diagnosis Each elytron with ten rows of small punctures located in sharply marked narrow grooves forming elytral striae; pronotum 1.3× as long as broad; scape only 4.33× as long as antennomere 3, and antennomeres 3, 9 and 10 equal in length. Description Body (Fig. 8A, E, J) relatively stout, brown, length 3.33 mm. Head (Fig. 8B, D, F, G) elongate, length 0.55 mm, width 0.50 mm; occipital constriction broader than half width of head, vertex transverse and evenly convex; frons subtrapezoidal, between antennal insertions forming subtriangular projection with shallow impression behind its middle; eyes large and strongly projecting from the silhouette of the head. Maxillary palp (Fig. 8H) slightly longer than head, palpomere 2 slender and in proximal half nearly cylindrical, then gradually broadening to apex; palpomeres 3 and 4 combined shorter than 2; palpomere 3 elongate, gradually and strongly broadening from base to apex; palpomere 4 strongly broadening from base to apex, with rounded apical margin. Punctures on frons and vertex fine, inconspicuous; setae short, moderately dense, suberect. Antennae (Fig. 8G–I) much shorter than body, length 2.46 mm, relative lengths of antennomeres (the shortest antennomere 3 as 1): 4.33: 2.17: 1.00: 1.17: 1.25: 1.17: 1.17: 1.08: 1.00: 1.00: 1.08. Scape with five or six pairs of long, ventral spines; pedicel with four pairs of similar spines; basic vestiture of all antennomeres short, moderately dense and recumbent, all antennomeres with at least several long and suberect setae. Pronotum (Fig. 8B, H) elongate and broadest near anterior third, length 0.78 mm, width 0.60 mm, pronotal index 1.29; disc convex, with indistinct transverse basal impression and covered with distinct, unevenly distributed punctures separated by spaces 0.5–2 times as wide as their diameters, setae short, sparse, suberect. Mesoventral intercoxal process (Fig. 8K) carinate, slender, parallel-sided, weakly elevated, mesoventrite in front of mesocoxal cavities evenly convex. Metaventrite (Fig. 8K) subtrapezoidal, broadening posteriorly, metacoxae broadly separated. Elytra (Fig. 8C, E, J) strikingly broader than pronotum, strongly convex, broadest slightly behind middle, length 2.00 mm, width 1.40 mm, elytral index 1.43; each elytron with ten narrow and deeply impressed striae with small and shallow punctures, six striae are visible in dorsal view, striae 1 and 3 (counting from elytral suture) connected posteriorly; adsutural region distinctly raised in posterior half of elytra; humeral calli prominent and short; elytra sparsely covered with short suberect setae forming single or double slightly irregular rows between striae. Legs (Fig. 8A, E, F) long and slender, unmodified. Hind wings present, right wing protruding from under elytra (Figs 8A; Supporting Information, Fig. S7). Etymology The name striatipennis is an adjective that refers to the fully striate elytra. Type locality and horizon Russia, Kaliningrad; Upper Eocene. Remarks This species clearly differs from previously described †B. antennatus and †B. horribilis in the fully developed elytral striae, while in the two previously described species the striae are incomplete and marked only near the elytral base. †Baltostigus striatipennis also has clearly different proportions of the antennomeres, with scape 4.33× as long as antennomere 3 (7.0–7.2× in †B. antennatus and †B. horribilis), and antennomeres 3, 9 and 10 equal in length (antennomeres 9 and 10 1.29–1.6× as long as 3 in †B. antennatus and †B. horribilis). A narrow adsutural region distinctly elevated in the posterior third of the elytra in the female of †B. striatipennis resembles a similar modification in females of some extant species of Mastigini, especially in Stenomastigus. Males of such species are always much more slender and their elytra are evenly convex. However, in Stenomastigus the female elytra have impressions near their anterior fourth to receive the trochanters of males during copulation, which is an adaptation to stabilize the mating position (Jałoszyński et al., 2015). Such a structure was not present in females of †Baltostigus, and therefore mating strategies might have differed from those in Mastigini, their sister-clade. Mastigini Fleming, 1821 sensu nov. Type genus: Mastigus Latreille, 1802. Diagnosis Mastigini are restricted here to genera sharing: an enlarged and ventrally spiny scape and pedicel; elongate head with median longitudinal groove on posteriorly impressed vertex; narrowly separated antennal insertions; pronotum lacking posterior collar; and aedeagus asymmetrical, with one paramere distinctly shorter than the other one (in some cases only one paramere is visible, the other one is either vestigial or completely obliterated). †Clidicostigus Jałoszyński, Brunke & Bai, 2017 = Cascomastigus Yin & Cai, 2017 syn. nov. Remarks †Cascomastigus does not differ in any characters from †Clidicostigus; their diagnostic features, including uniquely shaped maxillary palps with an asymmetrical palpomere 4, and elytral striae, are identical. Neither structural nor spatiotemporal arguments support a separate placement of these taxa, and †Cascomastigus is here placed as a junior synonym of †Clidicostigus (the former name with the online publication date 2017.03.07; the latter 2017.01.03). DISCUSSION After recent discoveries of Cretaceous and Eocene fossils, Mastigitae became a Scydmaeninae supertribe with over 40% of genera known only from amber inclusions. Although morphologically well-studied and unambiguously documented since the Cenomanian, Mastigitae remained a group with surprisingly problematic phylogenetic relationships among its components. Clidicini, Leptomastacini and Mastigini in the traditional sense were established solely on the basis of extant genera. The monophyly of Clidicini was already questioned (Jałoszyński, 2012a, 2016b), and problems of Cai & Huang (2016) to place their †Cretoleptochromus in this tribe reflect unclear diagnoses and non-monophyly of Clidicini in the traditional sense that we aimed to improve here. As each new extinct genus was discovered, these additional character states considerably modified previous hypotheses of homology, topology and biogeography (O’Keefe, 2002; Jałoszyński, 2012a, 2016b, and present results), and it became clear that characters of the extant genera of Mastigitae are insufficient to reconstruct the evolutionary relationships among them. Our results based on a wider taxon sampling supported these suspicions. At this current stage of knowledge, we combined all available data to shed light on the evolution of this enigmatic group of ant-like stone beetles, and with new character states of extinct taxa included in phylogenetic reconstructions, we demonstrate that the present-day diversity of Mastigitae is relictual and extinctions played an important role in the observed disjunctive distribution of extant taxa. Reclassification of Mastigitae Based on the phylogenetic hypothesis shown in Figure 3, a reclassification of Mastigitae was unavoidable. The tribe Clidicini in its traditional sense (i.e. comprising Clidicus, Leptochromus, †Palaeoleptochromus, †Euroleptochromus, †Rovnoleptochromus and Papusus) was not resolved as a monophyletic unit. This explains previous problems to define Clidicini. In one of the most recent attempts, O’Keefe (2002) listed an elongated maxillary palpomere 3 (vs. subtriangular or only as long as wide at apex in the remaining Mastigitae); elongate, dorsoventrally curved aedeagus with large parameres and ‘reduced’ cylindrical median lobe (vs. elongate and somewhat dorsoventrally curved but ‘otherwise different’ in Leptomastacini, and highly asymmetrical in Mastigini); and labial palpomere 3 elongate and slender (vs. short) as synapomorphies to distinguish Clidicini from all remaining Mastigitae. However, an elongate maxillary palpomere 3 of a very similar shape can be found in Mastigini; the differences in aedeagal structures were explained in a very unclear way and in fact the aedeagi of Leptomastacini and Clidicini sensu O’Keefe differ merely in the shape of parameral apices; and the labial palpomere 3 is strongly elongate and slender in all Mastigitae (somewhat reduced in relation to palpomere 2 only in Mastigini). The new division of this problematic group of genera into Clidicini sensu nov., Papusini trib. nov. and Leptochromini trib. nov. improves the classification by naming monophyletic units as tribes and providing diagnostic characters to identify them. We also propose to separate extinct †Baltostigus from Mastigini, on the basis of clearly defined and numerous morphological differences in the maxillary palps, vertex, elytra and wings, mesoventral process and the aedeagus, and a presumed ancient, late Cretaceous or earlier divergence between these groups, despite the only moderately strong support for its monophyly in our analysis. Historical biogeography Recent discoveries of the first Cenomanian Clidicini sensu nov. (Cai & Huang, 2016; Yin et al., 2017a) and Mastigini sensu nov. (Jałoszyński et al., 2017a; Yin et al., 2017b) demonstrated the origins of all newly defined tribes (Fig. 3) to be at minimum ~99 Mya. Based on results of all reconstructions and the spatiotemporal distribution of known fossils and extant taxa, the hypothesis assuming the Northern Hemisphere origins of Mastigitae seems well corroborated by two of the three analyses reported. Analysis 3 of Supporting Information, Appendix S2 differs significantly in this regard but it also gave the most ambiguous results. Analysis 3 indicated Australia as a part of the ancestral Mastigitae distribution, which seems highly unlikely because only a single species occurs in Australia, and it seems to be derived within the Asian clade. It remains unclear, however, whether the ancestor of Mastigitae evolved in the North American or Eurasian part of Laurasia. Both alternate scenarios require several dispersal events to explain the current distribution of Mastigitae. The oldest fossils, however, come from the Cenomanian of Myanmar, and the only Cretaceous North American species of Clidicini is ∼19 Myr younger, which may indicate the Eurasian part of Laurasia, or more precisely its south-eastern portion, as the ancestral area for Mastigitae. In this scenario, the divergence between Leptomastacini and the remaining Mastigitae must have taken place before the earliest Cenomanian in the Eurasian part of Laurasia, possibly in its southern portion, followed by a dispersal of Leptomastacini into the present-day Mediterranean basin. Clidicini have been evolving in situ, in south-eastern Laurasia, and dispersed to the west (i.e. to its North American part) during the Campanian or earlier, where Nearctic †Palaeoleptochromus and the entire Clidicini lineage has since gone extinct. Clidicini has also dispersed from SE Asia into northern Australia via Sundaland, presumably recently, during the Pleistocene low sea-level periods (e.g. Metcalfe et al., 2001; Bruyn et al., 2014) and into the Indian subcontinent, no earlier than the Paleogene when it collided with the Eurasian Plate (e.g. Aitchison et al., 2007). The morphological similarity of western Laurasian Campanian †Palaeoleptochromus and south-eastern Laurasian Cenomanian Clidicus (= Cretoleptochromus), and the location of the present-day biodiversity center of Clidicus in SE Asia support this scenario of Clidicini evolution and dispersal. Papusus, treated here as the sole member of Papusini, is morphologically different from all remaining Mastigitae and may represent an offshoot of the eastern Laurasian Mastigitae lineage that has dispersed into the western (North American) part of the Laurasian supercontinent, and diverged no later than the Cenomanian when members of part of its sister lineage (Mastigini) were already present. The dispersal of Papusini, however, might have occurred later; there is no fossil evidence to address this issue. Leptochromini are currently distributed in Central and South America, but fossils unambiguously placed in this tribe are known from the Eocene of Europe. Moreover, †Leptochromus palaeomexicanus was found in Oligocene/Miocene (22–26 Mya) Chiapas Mexican amber. The ancestral Leptochromini lineage, according to the scenario proposed here, has evolved within the Eurasian part of Laurasia and split twice: into the †Rovnoleptochromus lineage and †Euroleptochromus + Leptochromus. The former survived in the area of present-day Ukraine at least until the Priabonian. Later, the Leptochromus + †Euroleptochromus lineage split and Leptochromus dispersed into North America, from where it dispersed further southwards to colonize northern South America. The Leptochromus lineage has successfully survived until today, although it is poor in species and morphologically very uniform, while the European †Rovnoleptochromus and †Euroleptochromus lineages have gone extinct, presumably as a result of the Eocene–Oligocene climate cooling (e.g. Liu et al., 2009). According to our results, the ancestral lineage of Mastigitae that gave rise to †Baltostigini and Mastigini also evolved in the Eurasian part of Laurasia, and its divergence into two tribes may be quite ancient, no later than the Cenomanian, as Mastigini (i.e. †Clidicostigus) is known from Myanmar amber. Mastigini and †Baltostigini were widespread within eastern Laurasia, where the northern †Baltostigini clade had gone extinct (presumably during the Eocene–Oligocene climate cooling), and the southern (currently Mediterranean) Mastigini has survived and relatively recently dispersed into South Africa. The hypothesis of recent divergence of European and South African species of Mastigini, as a result of dispersal followed by habitat fragmentation and formation of barriers, is strongly supported by the striking morphological similarity of these species, so much so that thus far Mastigus, Palaeostigus and Stenomastigus were placed in a polytomy in all attempts to resolve their relationships (Jałoszyński, 2012a, 2016b and the present study), and Palaeostigus occurs in both parts of this disjunctive range. Evolution of morphological structures The ancient differentiation of all newly defined Mastigitae tribes, disjunctions generated by extinctions of Cretaceous and Eocene taxa, and adaptations of modern taxa to live in strikingly different habitats (forest leaf litter, soil, under stones in arid deserts) probably explain the observed morphological distinctiveness of the five extant lineages (i.e. Australo-Oriental Clidicini; Neotropical Leptochromini; Mediterranean Leptomastacini; Mediterranean and South African Mastigini). The ancestor of Mastigitae, as inferred from reconstructions of ancestral character states (Supporting Information, Appendix S1), might have been similar to the extant Scydmaenini (the sister-group of Mastigitae). It was presumably a beetle smaller than any Cretaceous, Eocene or extant Clidicini and Mastigini, closer in body size to Leptomastacini, Papusini or Leptochromini (i.e. not exceeding 4 mm, but possibly smaller), lacking any conspicuous modifications of the antennae (except the scape at least as long as the head), maxillary palps and legs, with large eyes, pronotum lacking posterior collar, elytral base lacking foveae and the aedeagus resembling that of the extant Adrastia Broun or Pseudoeudesis Binaghi, i.e. symmetrical, with free, slender parameres and a simple, un-looped flagellum. The ancestor of Mastigitae clearly differed from Scydmaenini by the broadly separated antennal insertions and conspicuous rows of large and deep punctures on each elytron. In addition to forms strikingly similar to extant Mastigitae, the Upper Cretaceous of south-eastern Eurasia was inhabited by taxa with body modifications even more extreme than those of extant species. Among the extant taxa, Mastigini such as Stenomastigus have the most elongated body form, with extremely long legs and antennae, adaptations for life on the surface of the ground and plants, and for running quickly after prey (Jałoszyński, 2012b, 2016a). The hallmark of Mastigini, the enlarged and spiny scape and pedicel, is especially well-developed in Stenomastigus (e.g. Jałoszyński, 2012b). While distinctive, it does not function as a ‘springtail trap’ as initially hypothesized by Jałoszyński (2012a) and further discussed by Yin et al. (2017b) (Jałoszyński, unpublished observations). However, in the Upper Cretaceous †Clidicostigus (Fig. 1E) the body was even more slender, the legs almost monstrously elongate, and the scape and pedicel more enlarged than in Stenomastigus. It seems that a considerable morphological diversity of Mastigitae had evolved and differentiated already before the Cenomanian, and extreme morphotypes like †Clidicostigus have gone extinct. A similar case of an extinct extreme form was discovered recently among the glandulariine scydmaenines. The Turonian (∼90 Mya) †Hyperstenichnus Jałoszyński et al., morphologically similar to the extant mite-feeding Stenichnus Thomson, had strikingly much larger labial suckers to immobilize its apparently mite prey than any of its extant relatives (Jałoszyński et al., 2017b). These extreme morphological adaptations in Scydmaeninae have apparently been eliminated by evolution, as presumably less extreme forms were favoured by unknown factors of selective pressure. From a morphological and evolutionary standpoint, the recent discovery of Cenomanian †Clidicostigus and Eocene †Baltostigus have been most important for understanding the evolution of Mastigitae. The ancient †Clidicostigus looked similar to the extant Mastigini (especially Stenomastigus); it had an asymmetrical aedeagus and was presumably wingless (judging from the lack of humeral calli), consistent with its closest living relatives. The apex of the aedeagus of †Clidicostigus arachnipes, reconstructed by μCT in Jałoszyński et al. (2017a), is very similar to that of the extant South African Mastigus spinicornis, the type species of Mastigus (Fig. 9R vs. 9Q). Moreover, the copulatory piece in †Clidicostigus arachnipes was developed in a way similar to that of other Mastigini, suggesting a permanently everted and membranous endophallus (not preserved or impossible to visualize with μCT), and a presumably looped flagellum that cannot be extruded from the aedeagus during copulation (Jałoszyński et al., 2015). The much younger †Baltostigus (Figs 2F, 8) had a body conspicuously smaller and stouter than that of any Mastigini, fully developed wings and a symmetrical aedeagus (Fig. 9C–E), which was additionally symmetrically positioned inside the abdomen in repose (Fig. 9B), with its basal orifice facing up. Its aedeagus was similar to the copulatory organs of Leptomastacini (Fig. 9H–K), Clidicini sensu nov. (Fig. 9L–O) and Papusini (Fig. 9P), and its shape is indicative of a simple, non-looped flagellum that can be extruded during copulation (as that in Fig. 9O). Before the discovery of †Clidicostigus, the clearly plesiomorphic symmetrical aedeagal structure, elytral rows of punctures and the winged condition of †Baltostigus might have been interpreted as representing an ancestral lineage of extant Mastigini, and consequently the development of a larger and more slender body, reduction of elytral striae to barely discernible rudiments, loss of wings and, most importantly, the asymmetrization of male genitalia, could be presumed to have taken place relatively recently, after the Eocene (Jałoszyński, 2016b). †Clidicostigus with its deep elytral striae, lack of wings and an asymmetrical aedeagus falsified this hypothesis and demonstrated that the split between Mastigini sensu nov. and †Baltostigini had occurred much earlier, during or before the Cenomanian, and that during the Eocene both lineages co-existed in Eurasia. The ancestral character reconstructions and phylogenies obtained in our study support the hypothesis of a winged ancestor of Mastigini + †Baltostigini, with striate elytra and a symmetrical aedeagus. The latter is of great interest, as the asymmetrization of male genitalia is surprisingly ancient (having occurred 99 Mya or earlier), and triggered the development of the most unusual and unique copulation in the beetles, which is found in the extant South African Stenomastigus. The increasing asymmetrization of parameres in combination with an immovable flagellum and permanently everted membranous, inflatable endophallus led to copulation with the long paramere inserted into the subelytral space and stabilized with additional female elytral modifications (Jałoszyński et al., 2015). Copulation with a symmetrical aedeagus persisted in this lineage via †Baltostigini until at least the Eocene. Similar to the asymmetrization of male genitalia, the loss of flight in Mastigini must have occurred no later than ~99 Mya, possibly when forms similar to †Clidicostigus developed extremely long and slender legs for efficient hunting (like their living Mediterranean and South African relatives), and started to rely on running, instead of flying, as a dispersal method. The flightless condition was presumably ancestral for Mastigini, whereas the ancestor of Mastigini + winged †Baltostigini was capable of flight. The loss of wings must have independently taken place in the ancestor of Leptomastacini, a group that today includes exclusively wingless species. A third loss of wings has occurred within Clidicini sensu nov., as some extant species of Clidicus are wingless (e.g. C. bellator and C. crocodylus) and some have wings (e.g. C. abbotensis); the Cenomanian †C. burmiticus had apparently preserved the ancestral state with complete wings (Yin et al., 2017a). The fourth independent loss of wings occurred in the ancestor of Papusini, a group that today is wingless. Four independent losses of wings seem more plausible than an alternative scenario that assumes a single loss of wings in the ancestor of Mastigitae and three (in Clidicini, Leptochromini and †Baltostigini) reversals. However, multiple reversals are known among insects (e.g. Whiting et al., 2003), and such a scenario, or a mixed scenario of wing losses, reversals and repeated losses, cannot be ruled out. CONCLUSIONS Based on results of phylogenetic analyses comprising a wide extant and extinct taxon sampling, we reclassify Mastigitae into six monophyletic units: Leptomastacini, Clidicini, Papusini, Leptochromini, †Baltostigini and Mastigini. We postulate that Mastigitae have undergone a substantial morphological differentiation during or (more likely) before the Cenomanian, when members of Clidicini and Mastigini already inhabited south-eastern Laurasia and exhibited some highly derived character states; dispersals and extinctions are responsible for the current and highly disjunct distribution of this supertribe. Eurasia was inferred as the ancestral distribution area for Mastigitae, and an ancestor similar to the extant Scydmaenini, but with broadly separated antennal insertions and deep elytral striae was reconstructed. We demonstrate that the first step in the evolution of a highly asymmetrical aedeagus and extremely complex copulation in Stenomastigus occurred at least 99 Mya. Moreover, we infer four independent wing losses during the evolution of Mastigitae. As the first divergence in Mastigitae took place during or before the Late Cretaceous, presumably within south-eastern Laurasia, further study of Myanmar amber could be expected to yield members of Leptomastacini, a tribe still unknown in the fossil record. SUPPORTING INFORMATION Additional Supporting Information may be found in the online version of this article at the publisher’s web-site: Appendix S1. Reconstructed ancestral character states for Mastigitae. Appendix S2. Reconstruction of ancestral areas of distribution. Figure S1. Consensus (50% majority rule) tree obtained in Bayesian analysis; posterior probability values higher than 0.5 given at nodes. Figure S2. Clidicus (=Cretoleptochromus) sp. (AMNH Bu-SY17; Cenomanian of Myanmar). A, Dorsal habitus. B, elytra showing setation. C, elytra under different lighting, showing rows of punctures. D, ventral habitus. E, metaventrite and abdomen in ventral view. F, G, head in anterodorsal and slightly lateral view. H, head in anterolateral and slightly dorsal view. Scale bars: A–E: 2 mm; F–H: 0.5 mm. Figure S3. Clidicus (= Cretoleptochromus) sp. (AMNH Bu-SY17; Cenomanian of Myanmar). A, dorsal habitus (cf. S2 A). B, ventral habitus (cf. S2 D). C, head in anterodorsal and slightly lateral view (cf. S2 F–G). D, head in anterolateral and slightly dorsal view (cf. S2 H). Scale bars: A, B: 2 mm; C, D: 0.5 mm. Figure S4. Clidicus sp. (CCHH 1543-1; Upper Eocene of Russia). A, dorsal habitus. B, ventral habitus. C, head in dorsolateral view. D, head in ventrolateral view. Scale bars: A, B: 2 mm; C, D: 1 mm. Figure S5. Clidicus sp. (CCHH 1543-1; Upper Eocene of Russia). A, dorsal habitus (cf. S4 A). B, ventral habitus (cf. S4 B). C, head in dorsolateral view (cf. S4 C). D, head in ventrolateral view (cf. S4 D). Scale bars: A, B: 2 mm; C, D: 1 mm. Figure S6. Euroleptochromus sp. (CCHH 835-2; Upper Eocene of Russia). A, right lateral habitus. B, left laterodorsal habitus. C, head, prothorax and fore leg in lateral view. D, ventral habitus. Scale bars: 1mm. Figure S7. Female holotype of †Baltostigus striatipennis Jałoszyński, Brunke & Yamamoto sp. nov. (AMNH Bu-SY18; Upper Eocene of Russia). Scale bar: 1mm. Figure S8. Female holotype of †Baltostigus striatipennis Jałoszyński, Brunke & Yamamoto sp. nov. (AMNH Bu-SY18; Upper Eocene of Russia), detail of Fig. S7. Scale bar: 1mm. ACKNOWLEDGEMENTS We thank museum curators and collectors who made specimens available to us (including holotypes): Ming Bai (TGEM), Chengyang Cai (NIGP), Giulio Cuccodoro (MHNG), Christel and Hans Werner Hoffeins (CCHH), Ivan Löbl (MHNG), Heinrich Meybohm (cHM), Marc De Meyer (RMCA), Ruth Müller (TMSA), Evgeny Perkovsky (SIZK) and Harald Schillhammer (NHMW). MicroCT imaging of amber inclusions was performed by Brian Metscher (University of Vienna) with support from the EU project BIG4 ITN (see below). We also thank Viola Winkler (Metscher Lab, University of Vienna) for assistance with μCT reconstructions and scanning. Anna Siudzińska (Laboratory of Electron Microscopy, Wrocław Research Centre EIT+) is acknowledged for taking SEM micrographs. This project has received funding in the form of fellowships to AJB from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 642241 (BIG4) (Vienna, Austria), and the NSERC PRP program (Ottawa, Canada). [Version of Record, published online 19 April 2018; http://zoobank.org/urn:lsid:zoobank.org:pub:32E47418-1241-4DAB-BB92-9E2139CB3006] APPENDIX 1 Study methods are as follows: perm., disarticulated specimen in permanent slide preparations; LM, light microscopy; μCT, microcomputer tomography; SEM, gold-coated disarticulated specimen examined by a scanning electron microscopy; temp., intact specimen in temporary slide preparation; if characters were extracted from literature and the type material has not been examined, an appropriate citation is given instead of the study method and depository; HT and PT stand for holotype and paratype, respectively. Terminal taxa (alphabetically) and data of specimens used in the phylogenetic analysis Terminal taxon Country of origin Sex Study method Depository* Euaesthetinae Euaesthetus ruficapillus (Lacordaire, 1835) Poland ♂, ♀ SEM, LM/perm. cPJ Scydmaeninae: Scydmaenini Adrastia edwardsi (Sharp, 1874) New Zealand ♂ LM/temp. NHMW Pseudoeudesis sulcipennis (Reitter, 1890) Tunisia ♂, ♀ LM/temp. MNHW Scydmaenus tarsatus Müller & Kunze, 1822 Poland ♂, ♀ SEM, LM/perm. cPJ Scydmaeninae: Mastigitae Ablepton trefortiFrivaldszky, 1877 Romania ♂, ♀ SEM, LM/perm. cPJ †Baltostigus antennatus Jałoszyński, 2016 Eocene of Poland ♂ μCT, LM CCHH/SDEI †Baltostigus horribilis Jałoszyński, 2016 Eocene of Lithuania ? LM FMNH †Baltostigus striatipennis sp. nov. (AMNH Bu-SY18) Eocene of Russia ♀ μCT, LM AMNH †Cascomastigus monstrabilis Yin & Cai, 2017 Cenomanian of Myanmar HT ♂, PT ♀ Yin et al., 2017 †Clidicostigus arachnipes Jałoszyński et al., 2017 Cenomanian of Myanmar HT ♂ μCT, LM TGEM Clidicus bellator Jałoszyński et al., 2003 Vietnam PT ♂, PT ♀ SEM, LM/perm. cPJ Clidicus formicarius Pascoe, 1866 Borneo ♂, ♀ SEM, LM cPJ †Cretoleptochromus archaicus Cai & Huang, 2016 Cenomanian of Myanmar HT? LM NIGP †Cretoleptochromus burmiticus Yin et al., 2017 Cenomanian of Myanmar HT ♂, PT ♂, PT ♀ Yin et al., 2017 †Cretoleptochromus sp. (AMNH Bu-SY17) Cenomanian of Myanmar ♂ LM AMNH †Euroleptochromus sabathi Jałoszyński, 2012 Eocene of Lithuania HT ♀ LM FMNH †Euroleptochromus setifer sp. nov. (CCHH 835-3) Eocene of Russia HT ♀, PT ♀ μCT, LM CCHH/SDEI Leptochromus agilis (Sharp, 1887) Costa Rica ♂, ♀ LM/temp. MHNG Leptochromus laselva Lord et al., 2014 Costa Rica PT ♂, PT ♀ SEM, LM/temp. cPJ Leptomastax stussineri Reitter, 1880 Bulgaria ♂, ♀ SEM, LM/perm. cPJ Mastigus spinicornis (Fabricius, 1787) RSA ♂, ♀ LM/temp. RMCA †Palaeoleptochromus schaufussi O’Keefe, 1997 Campanian of Canada ♀ O’Keefe et al., 1997 Palaeostigus bifoveolatus (Boheman, 1851) RSA ♂, ♀ SEM, LM/perm. cPJ Palaeostigus ruficornis schimitscheki (Machulka, 1944) Turkey ♂, ♀ SEM, LM/perm. cPJ Papusus macer Casey, 1897 USA ♂, ♀ SEM, LM/temp. cPJ †Rovnoleptochromus ableptonoides Jałoszyński & Perkovsky, 2016 Eocene of Ukraine ? LM SIZK Stenomastigus varii Leleup, 1968 RSA ♂, ♀ SEM, LM/perm. TMSA Taurablepton asitawandas Besuchet, 1969 Turkey ♀ LM/temp. MHNG Taurablepton sp. Turkey ♂ SEM, LM/temp. cHM Terminal taxon Country of origin Sex Study method Depository* Euaesthetinae Euaesthetus ruficapillus (Lacordaire, 1835) Poland ♂, ♀ SEM, LM/perm. cPJ Scydmaeninae: Scydmaenini Adrastia edwardsi (Sharp, 1874) New Zealand ♂ LM/temp. NHMW Pseudoeudesis sulcipennis (Reitter, 1890) Tunisia ♂, ♀ LM/temp. MNHW Scydmaenus tarsatus Müller & Kunze, 1822 Poland ♂, ♀ SEM, LM/perm. cPJ Scydmaeninae: Mastigitae Ablepton trefortiFrivaldszky, 1877 Romania ♂, ♀ SEM, LM/perm. cPJ †Baltostigus antennatus Jałoszyński, 2016 Eocene of Poland ♂ μCT, LM CCHH/SDEI †Baltostigus horribilis Jałoszyński, 2016 Eocene of Lithuania ? LM FMNH †Baltostigus striatipennis sp. nov. (AMNH Bu-SY18) Eocene of Russia ♀ μCT, LM AMNH †Cascomastigus monstrabilis Yin & Cai, 2017 Cenomanian of Myanmar HT ♂, PT ♀ Yin et al., 2017 †Clidicostigus arachnipes Jałoszyński et al., 2017 Cenomanian of Myanmar HT ♂ μCT, LM TGEM Clidicus bellator Jałoszyński et al., 2003 Vietnam PT ♂, PT ♀ SEM, LM/perm. cPJ Clidicus formicarius Pascoe, 1866 Borneo ♂, ♀ SEM, LM cPJ †Cretoleptochromus archaicus Cai & Huang, 2016 Cenomanian of Myanmar HT? LM NIGP †Cretoleptochromus burmiticus Yin et al., 2017 Cenomanian of Myanmar HT ♂, PT ♂, PT ♀ Yin et al., 2017 †Cretoleptochromus sp. (AMNH Bu-SY17) Cenomanian of Myanmar ♂ LM AMNH †Euroleptochromus sabathi Jałoszyński, 2012 Eocene of Lithuania HT ♀ LM FMNH †Euroleptochromus setifer sp. nov. (CCHH 835-3) Eocene of Russia HT ♀, PT ♀ μCT, LM CCHH/SDEI Leptochromus agilis (Sharp, 1887) Costa Rica ♂, ♀ LM/temp. MHNG Leptochromus laselva Lord et al., 2014 Costa Rica PT ♂, PT ♀ SEM, LM/temp. cPJ Leptomastax stussineri Reitter, 1880 Bulgaria ♂, ♀ SEM, LM/perm. cPJ Mastigus spinicornis (Fabricius, 1787) RSA ♂, ♀ LM/temp. RMCA †Palaeoleptochromus schaufussi O’Keefe, 1997 Campanian of Canada ♀ O’Keefe et al., 1997 Palaeostigus bifoveolatus (Boheman, 1851) RSA ♂, ♀ SEM, LM/perm. cPJ Palaeostigus ruficornis schimitscheki (Machulka, 1944) Turkey ♂, ♀ SEM, LM/perm. cPJ Papusus macer Casey, 1897 USA ♂, ♀ SEM, LM/temp. cPJ †Rovnoleptochromus ableptonoides Jałoszyński & Perkovsky, 2016 Eocene of Ukraine ? LM SIZK Stenomastigus varii Leleup, 1968 RSA ♂, ♀ SEM, LM/perm. TMSA Taurablepton asitawandas Besuchet, 1969 Turkey ♀ LM/temp. MHNG Taurablepton sp. Turkey ♂ SEM, LM/temp. cHM * Depository abbreviations: cHM – collection of Heinrich Meybohm, Großhansdorf, Germany. cPJ – collection of Paweł Jałoszyński, Wrocław, Poland. AMNH – American Museum of Natural History, New York, USA. CCHH/SDEI – collection of Christel & Hans Werner Hoffeins, Hamburg, Germany, with final depository at the Senckenberg Deutsches Entomologisches Institut Müncheberg, Germany. FMNH – Field Museum of Natural History, Chicago, USA. MNHW – Museum of Natural History, University of Wrocław, Wrocław, Poland. NHMW – Naturhistorisches Museum Wien, Vienna, Austria. NIGP – Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, China. RMCA – Musée Royal de l’Afrique Centrale, Tervuren, Belgium. SIZK – Schmalhausen Institute of Zoology, National Academy of Sciences of Ukraine, Kiev, Ukraine. TGEM – Three Gorges Entomological Museum, Chongqing, China. TMSA – Ditsong National Museum of National History, Pretoria, RSA. View Large Terminal taxon Country of origin Sex Study method Depository* Euaesthetinae Euaesthetus ruficapillus (Lacordaire, 1835) Poland ♂, ♀ SEM, LM/perm. cPJ Scydmaeninae: Scydmaenini Adrastia edwardsi (Sharp, 1874) New Zealand ♂ LM/temp. NHMW Pseudoeudesis sulcipennis (Reitter, 1890) Tunisia ♂, ♀ LM/temp. MNHW Scydmaenus tarsatus Müller & Kunze, 1822 Poland ♂, ♀ SEM, LM/perm. cPJ Scydmaeninae: Mastigitae Ablepton trefortiFrivaldszky, 1877 Romania ♂, ♀ SEM, LM/perm. cPJ †Baltostigus antennatus Jałoszyński, 2016 Eocene of Poland ♂ μCT, LM CCHH/SDEI †Baltostigus horribilis Jałoszyński, 2016 Eocene of Lithuania ? LM FMNH †Baltostigus striatipennis sp. nov. (AMNH Bu-SY18) Eocene of Russia ♀ μCT, LM AMNH †Cascomastigus monstrabilis Yin & Cai, 2017 Cenomanian of Myanmar HT ♂, PT ♀ Yin et al., 2017 †Clidicostigus arachnipes Jałoszyński et al., 2017 Cenomanian of Myanmar HT ♂ μCT, LM TGEM Clidicus bellator Jałoszyński et al., 2003 Vietnam PT ♂, PT ♀ SEM, LM/perm. cPJ Clidicus formicarius Pascoe, 1866 Borneo ♂, ♀ SEM, LM cPJ †Cretoleptochromus archaicus Cai & Huang, 2016 Cenomanian of Myanmar HT? LM NIGP †Cretoleptochromus burmiticus Yin et al., 2017 Cenomanian of Myanmar HT ♂, PT ♂, PT ♀ Yin et al., 2017 †Cretoleptochromus sp. (AMNH Bu-SY17) Cenomanian of Myanmar ♂ LM AMNH †Euroleptochromus sabathi Jałoszyński, 2012 Eocene of Lithuania HT ♀ LM FMNH †Euroleptochromus setifer sp. nov. (CCHH 835-3) Eocene of Russia HT ♀, PT ♀ μCT, LM CCHH/SDEI Leptochromus agilis (Sharp, 1887) Costa Rica ♂, ♀ LM/temp. MHNG Leptochromus laselva Lord et al., 2014 Costa Rica PT ♂, PT ♀ SEM, LM/temp. cPJ Leptomastax stussineri Reitter, 1880 Bulgaria ♂, ♀ SEM, LM/perm. cPJ Mastigus spinicornis (Fabricius, 1787) RSA ♂, ♀ LM/temp. RMCA †Palaeoleptochromus schaufussi O’Keefe, 1997 Campanian of Canada ♀ O’Keefe et al., 1997 Palaeostigus bifoveolatus (Boheman, 1851) RSA ♂, ♀ SEM, LM/perm. cPJ Palaeostigus ruficornis schimitscheki (Machulka, 1944) Turkey ♂, ♀ SEM, LM/perm. cPJ Papusus macer Casey, 1897 USA ♂, ♀ SEM, LM/temp. cPJ †Rovnoleptochromus ableptonoides Jałoszyński & Perkovsky, 2016 Eocene of Ukraine ? LM SIZK Stenomastigus varii Leleup, 1968 RSA ♂, ♀ SEM, LM/perm. TMSA Taurablepton asitawandas Besuchet, 1969 Turkey ♀ LM/temp. MHNG Taurablepton sp. Turkey ♂ SEM, LM/temp. cHM Terminal taxon Country of origin Sex Study method Depository* Euaesthetinae Euaesthetus ruficapillus (Lacordaire, 1835) Poland ♂, ♀ SEM, LM/perm. cPJ Scydmaeninae: Scydmaenini Adrastia edwardsi (Sharp, 1874) New Zealand ♂ LM/temp. NHMW Pseudoeudesis sulcipennis (Reitter, 1890) Tunisia ♂, ♀ LM/temp. MNHW Scydmaenus tarsatus Müller & Kunze, 1822 Poland ♂, ♀ SEM, LM/perm. cPJ Scydmaeninae: Mastigitae Ablepton trefortiFrivaldszky, 1877 Romania ♂, ♀ SEM, LM/perm. cPJ †Baltostigus antennatus Jałoszyński, 2016 Eocene of Poland ♂ μCT, LM CCHH/SDEI †Baltostigus horribilis Jałoszyński, 2016 Eocene of Lithuania ? LM FMNH †Baltostigus striatipennis sp. nov. (AMNH Bu-SY18) Eocene of Russia ♀ μCT, LM AMNH †Cascomastigus monstrabilis Yin & Cai, 2017 Cenomanian of Myanmar HT ♂, PT ♀ Yin et al., 2017 †Clidicostigus arachnipes Jałoszyński et al., 2017 Cenomanian of Myanmar HT ♂ μCT, LM TGEM Clidicus bellator Jałoszyński et al., 2003 Vietnam PT ♂, PT ♀ SEM, LM/perm. cPJ Clidicus formicarius Pascoe, 1866 Borneo ♂, ♀ SEM, LM cPJ †Cretoleptochromus archaicus Cai & Huang, 2016 Cenomanian of Myanmar HT? LM NIGP †Cretoleptochromus burmiticus Yin et al., 2017 Cenomanian of Myanmar HT ♂, PT ♂, PT ♀ Yin et al., 2017 †Cretoleptochromus sp. (AMNH Bu-SY17) Cenomanian of Myanmar ♂ LM AMNH †Euroleptochromus sabathi Jałoszyński, 2012 Eocene of Lithuania HT ♀ LM FMNH †Euroleptochromus setifer sp. nov. (CCHH 835-3) Eocene of Russia HT ♀, PT ♀ μCT, LM CCHH/SDEI Leptochromus agilis (Sharp, 1887) Costa Rica ♂, ♀ LM/temp. MHNG Leptochromus laselva Lord et al., 2014 Costa Rica PT ♂, PT ♀ SEM, LM/temp. cPJ Leptomastax stussineri Reitter, 1880 Bulgaria ♂, ♀ SEM, LM/perm. cPJ Mastigus spinicornis (Fabricius, 1787) RSA ♂, ♀ LM/temp. RMCA †Palaeoleptochromus schaufussi O’Keefe, 1997 Campanian of Canada ♀ O’Keefe et al., 1997 Palaeostigus bifoveolatus (Boheman, 1851) RSA ♂, ♀ SEM, LM/perm. cPJ Palaeostigus ruficornis schimitscheki (Machulka, 1944) Turkey ♂, ♀ SEM, LM/perm. cPJ Papusus macer Casey, 1897 USA ♂, ♀ SEM, LM/temp. cPJ †Rovnoleptochromus ableptonoides Jałoszyński & Perkovsky, 2016 Eocene of Ukraine ? LM SIZK Stenomastigus varii Leleup, 1968 RSA ♂, ♀ SEM, LM/perm. TMSA Taurablepton asitawandas Besuchet, 1969 Turkey ♀ LM/temp. MHNG Taurablepton sp. Turkey ♂ SEM, LM/temp. cHM * Depository abbreviations: cHM – collection of Heinrich Meybohm, Großhansdorf, Germany. cPJ – collection of Paweł Jałoszyński, Wrocław, Poland. AMNH – American Museum of Natural History, New York, USA. CCHH/SDEI – collection of Christel & Hans Werner Hoffeins, Hamburg, Germany, with final depository at the Senckenberg Deutsches Entomologisches Institut Müncheberg, Germany. FMNH – Field Museum of Natural History, Chicago, USA. MNHW – Museum of Natural History, University of Wrocław, Wrocław, Poland. NHMW – Naturhistorisches Museum Wien, Vienna, Austria. NIGP – Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, China. RMCA – Musée Royal de l’Afrique Centrale, Tervuren, Belgium. SIZK – Schmalhausen Institute of Zoology, National Academy of Sciences of Ukraine, Kiev, Ukraine. TGEM – Three Gorges Entomological Museum, Chongqing, China. TMSA – Ditsong National Museum of National History, Pretoria, RSA. View Large APPENDIX 2 Morphological data matrix for phylogenetic analysis of the supertribe Mastigitae 0000000000 1111111111 2222222222 3333333333 4444444444 5555555555 666666666 0123456789 0123456789 0123456789 0123456789 0123456789 0123456789 012345678 Euaesthetus ruficapillus 0011000000 0–01000000 10––100000 0–110010000 1011000000 000000000 1–0000001 Scydmaenus tarsatus 0000000000 0–00110000 10––111010 0–010000000 1010010000 000000000 1–1110001 Adrastia edwardsi 0000000000 0–01010000 10––111010 0–0100001– 0101001001 0000000000 1–0110001 Pseudoeudesis sulcipennis 0000000000 0–1–0?0000 10––111010 0–01001000 0101000001 0000000000 1–1110001 Ablepton treforti 1000000110 0–11100001 10––0001200–1100010 1110010001 1111010000 1010010000 Taurablepton asitawandas 1010000110 0–1–100001 10––0001200–1100110 1110010000 1111010000 000001???? Taurablepton sp. 1010000110 0–1–100001 10––0001200–1100110 1110010000 1111010000 0000010000 Leptomastax stussineri 1020000110 0–11100001 10––0001200–1100110 1110010000 1111010000 0010010000 Palaeostigus ruficornis 0000011010 0–00110000 010111122 1110111000 1111011110 0000100001 0000001111 Palaeostigus bifoveolatus 0000011010 0–00110000 010111122 1110111000 1111011110 0000100001 0000001111 Stenomastigus varii 0000011010 0–00110000 0101111221110111001–001111110 0000100001 0000001111 Mastigus spinicornis 0000011010 0–00110000 010111122 1110111000 1001111110 0000100001 0000001111 Clidicostigus arachnipes 00000??010 0–00110100 01001?1221 1101???0?? ?????????? ?????000?? 0–0????1? Cascomastigus monstrabilis 000????010 0–00?10100 01001?1221 1101?????? ?????????? ?????000?? 0–0?????? Clidicus bellator 0111101010 0–01010101 10––100120 0–0000001– 110001000 1001100010 0010010001 Clidicus formicarius 0101101011 0–01110111 10––100220 100000001– 110001000 1001100010 0010010001 Papusus macer 0011101010 0–01110000 10––101120 0–0100001–11010??00 0000010000 0000000001 Palaeoleptochromus schaufussi 0?21?01111 0–01??0011 10––1?0220 100????0?? ?????????? ??????01?? ?–??????? Leptochromus agilis 0001101011 1001111100 0101100220 0–0000100 1110101000 0110101100 0010000001 Leptochromus laselva 0001101011 1101111100 0101100220 0–0000100 1110101000 0110101100 0010000001 Euroleptochromus sabathi 0001?01011 1101??1100 11011?0220 0–000?10? ??10?0?000 0??0001100 0010?????? Euroleptochromus setifer 0001101011 1101??1100 1101100220 0–0000100 1?1000?000 0??0001100 0010?????? Baltostigus horribilis 0000100010 0–01?1001 001111?122 11101???0? ??????1100 0??0000000 0000?????? Baltostigus antennatus 0000100010 0–01??001 001111?122 11101???0? ?????????0 ???0??0000 ?010?1??01 Baltostigus striatipennis 0000100010 0–0111001 001111?122 11101??00? ??00101100 0??0000000 0010?????? Rovnoleptochromus ableptonoides 0001?0?011 0–01110101 0101100220 0–00???0? ???0?1?001 ???0001000 1010?????? Cretoleptochromus archaicus 0111101011 0–0111011? ?0––10022 01000?000? ??10?0?001 ???1100010 0010?????? Cretoleptochromus burmiticus 0121?0?011 0–01110110 10––1?022 01000?010? ?????????? ?????0001? ?010?1??0? Cretoleptochromus sp. 01111?101? 0–01110111 10––1?0220 1000???0? ?????????0? ??11000?00 010?1??11 0000000000 1111111111 2222222222 3333333333 4444444444 5555555555 666666666 0123456789 0123456789 0123456789 0123456789 0123456789 0123456789 012345678 Euaesthetus ruficapillus 0011000000 0–01000000 10––100000 0–110010000 1011000000 000000000 1–0000001 Scydmaenus tarsatus 0000000000 0–00110000 10––111010 0–010000000 1010010000 000000000 1–1110001 Adrastia edwardsi 0000000000 0–01010000 10––111010 0–0100001– 0101001001 0000000000 1–0110001 Pseudoeudesis sulcipennis 0000000000 0–1–0?0000 10––111010 0–01001000 0101000001 0000000000 1–1110001 Ablepton treforti 1000000110 0–11100001 10––0001200–1100010 1110010001 1111010000 1010010000 Taurablepton asitawandas 1010000110 0–1–100001 10––0001200–1100110 1110010000 1111010000 000001???? Taurablepton sp. 1010000110 0–1–100001 10––0001200–1100110 1110010000 1111010000 0000010000 Leptomastax stussineri 1020000110 0–11100001 10––0001200–1100110 1110010000 1111010000 0010010000 Palaeostigus ruficornis 0000011010 0–00110000 010111122 1110111000 1111011110 0000100001 0000001111 Palaeostigus bifoveolatus 0000011010 0–00110000 010111122 1110111000 1111011110 0000100001 0000001111 Stenomastigus varii 0000011010 0–00110000 0101111221110111001–001111110 0000100001 0000001111 Mastigus spinicornis 0000011010 0–00110000 010111122 1110111000 1001111110 0000100001 0000001111 Clidicostigus arachnipes 00000??010 0–00110100 01001?1221 1101???0?? ?????????? ?????000?? 0–0????1? Cascomastigus monstrabilis 000????010 0–00?10100 01001?1221 1101?????? ?????????? ?????000?? 0–0?????? Clidicus bellator 0111101010 0–01010101 10––100120 0–0000001– 110001000 1001100010 0010010001 Clidicus formicarius 0101101011 0–01110111 10––100220 100000001– 110001000 1001100010 0010010001 Papusus macer 0011101010 0–01110000 10––101120 0–0100001–11010??00 0000010000 0000000001 Palaeoleptochromus schaufussi 0?21?01111 0–01??0011 10––1?0220 100????0?? ?????????? ??????01?? ?–??????? Leptochromus agilis 0001101011 1001111100 0101100220 0–0000100 1110101000 0110101100 0010000001 Leptochromus laselva 0001101011 1101111100 0101100220 0–0000100 1110101000 0110101100 0010000001 Euroleptochromus sabathi 0001?01011 1101??1100 11011?0220 0–000?10? ??10?0?000 0??0001100 0010?????? Euroleptochromus setifer 0001101011 1101??1100 1101100220 0–0000100 1?1000?000 0??0001100 0010?????? Baltostigus horribilis 0000100010 0–01?1001 001111?122 11101???0? ??????1100 0??0000000 0000?????? Baltostigus antennatus 0000100010 0–01??001 001111?122 11101???0? ?????????0 ???0??0000 ?010?1??01 Baltostigus striatipennis 0000100010 0–0111001 001111?122 11101??00? ??00101100 0??0000000 0010?????? Rovnoleptochromus ableptonoides 0001?0?011 0–01110101 0101100220 0–00???0? ???0?1?001 ???0001000 1010?????? Cretoleptochromus archaicus 0111101011 0–0111011? ?0––10022 01000?000? ??10?0?001 ???1100010 0010?????? Cretoleptochromus burmiticus 0121?0?011 0–01110110 10––1?022 01000?010? ?????????? ?????0001? ?010?1??0? Cretoleptochromus sp. 01111?101? 0–01110111 10––1?0220 1000???0? ?????????0? ??11000?00 010?1??11 ‘–’ indicates inapplicable characters. ‘?’ indicates missing data. View Large 0000000000 1111111111 2222222222 3333333333 4444444444 5555555555 666666666 0123456789 0123456789 0123456789 0123456789 0123456789 0123456789 012345678 Euaesthetus ruficapillus 0011000000 0–01000000 10––100000 0–110010000 1011000000 000000000 1–0000001 Scydmaenus tarsatus 0000000000 0–00110000 10––111010 0–010000000 1010010000 000000000 1–1110001 Adrastia edwardsi 0000000000 0–01010000 10––111010 0–0100001– 0101001001 0000000000 1–0110001 Pseudoeudesis sulcipennis 0000000000 0–1–0?0000 10––111010 0–01001000 0101000001 0000000000 1–1110001 Ablepton treforti 1000000110 0–11100001 10––0001200–1100010 1110010001 1111010000 1010010000 Taurablepton asitawandas 1010000110 0–1–100001 10––0001200–1100110 1110010000 1111010000 000001???? Taurablepton sp. 1010000110 0–1–100001 10––0001200–1100110 1110010000 1111010000 0000010000 Leptomastax stussineri 1020000110 0–11100001 10––0001200–1100110 1110010000 1111010000 0010010000 Palaeostigus ruficornis 0000011010 0–00110000 010111122 1110111000 1111011110 0000100001 0000001111 Palaeostigus bifoveolatus 0000011010 0–00110000 010111122 1110111000 1111011110 0000100001 0000001111 Stenomastigus varii 0000011010 0–00110000 0101111221110111001–001111110 0000100001 0000001111 Mastigus spinicornis 0000011010 0–00110000 010111122 1110111000 1001111110 0000100001 0000001111 Clidicostigus arachnipes 00000??010 0–00110100 01001?1221 1101???0?? ?????????? ?????000?? 0–0????1? Cascomastigus monstrabilis 000????010 0–00?10100 01001?1221 1101?????? ?????????? ?????000?? 0–0?????? Clidicus bellator 0111101010 0–01010101 10––100120 0–0000001– 110001000 1001100010 0010010001 Clidicus formicarius 0101101011 0–01110111 10––100220 100000001– 110001000 1001100010 0010010001 Papusus macer 0011101010 0–01110000 10––101120 0–0100001–11010??00 0000010000 0000000001 Palaeoleptochromus schaufussi 0?21?01111 0–01??0011 10––1?0220 100????0?? ?????????? ??????01?? ?–??????? Leptochromus agilis 0001101011 1001111100 0101100220 0–0000100 1110101000 0110101100 0010000001 Leptochromus laselva 0001101011 1101111100 0101100220 0–0000100 1110101000 0110101100 0010000001 Euroleptochromus sabathi 0001?01011 1101??1100 11011?0220 0–000?10? ??10?0?000 0??0001100 0010?????? Euroleptochromus setifer 0001101011 1101??1100 1101100220 0–0000100 1?1000?000 0??0001100 0010?????? Baltostigus horribilis 0000100010 0–01?1001 001111?122 11101???0? ??????1100 0??0000000 0000?????? Baltostigus antennatus 0000100010 0–01??001 001111?122 11101???0? ?????????0 ???0??0000 ?010?1??01 Baltostigus striatipennis 0000100010 0–0111001 001111?122 11101??00? ??00101100 0??0000000 0010?????? Rovnoleptochromus ableptonoides 0001?0?011 0–01110101 0101100220 0–00???0? ???0?1?001 ???0001000 1010?????? Cretoleptochromus archaicus 0111101011 0–0111011? ?0––10022 01000?000? ??10?0?001 ???1100010 0010?????? Cretoleptochromus burmiticus 0121?0?011 0–01110110 10––1?022 01000?010? ?????????? ?????0001? ?010?1??0? Cretoleptochromus sp. 01111?101? 0–01110111 10––1?0220 1000???0? ?????????0? ??11000?00 010?1??11 0000000000 1111111111 2222222222 3333333333 4444444444 5555555555 666666666 0123456789 0123456789 0123456789 0123456789 0123456789 0123456789 012345678 Euaesthetus ruficapillus 0011000000 0–01000000 10––100000 0–110010000 1011000000 000000000 1–0000001 Scydmaenus tarsatus 0000000000 0–00110000 10––111010 0–010000000 1010010000 000000000 1–1110001 Adrastia edwardsi 0000000000 0–01010000 10––111010 0–0100001– 0101001001 0000000000 1–0110001 Pseudoeudesis sulcipennis 0000000000 0–1–0?0000 10––111010 0–01001000 0101000001 0000000000 1–1110001 Ablepton treforti 1000000110 0–11100001 10––0001200–1100010 1110010001 1111010000 1010010000 Taurablepton asitawandas 1010000110 0–1–100001 10––0001200–1100110 1110010000 1111010000 000001???? Taurablepton sp. 1010000110 0–1–100001 10––0001200–1100110 1110010000 1111010000 0000010000 Leptomastax stussineri 1020000110 0–11100001 10––0001200–1100110 1110010000 1111010000 0010010000 Palaeostigus ruficornis 0000011010 0–00110000 010111122 1110111000 1111011110 0000100001 0000001111 Palaeostigus bifoveolatus 0000011010 0–00110000 010111122 1110111000 1111011110 0000100001 0000001111 Stenomastigus varii 0000011010 0–00110000 0101111221110111001–001111110 0000100001 0000001111 Mastigus spinicornis 0000011010 0–00110000 010111122 1110111000 1001111110 0000100001 0000001111 Clidicostigus arachnipes 00000??010 0–00110100 01001?1221 1101???0?? ?????????? ?????000?? 0–0????1? Cascomastigus monstrabilis 000????010 0–00?10100 01001?1221 1101?????? ?????????? ?????000?? 0–0?????? Clidicus bellator 0111101010 0–01010101 10––100120 0–0000001– 110001000 1001100010 0010010001 Clidicus formicarius 0101101011 0–01110111 10––100220 100000001– 110001000 1001100010 0010010001 Papusus macer 0011101010 0–01110000 10––101120 0–0100001–11010??00 0000010000 0000000001 Palaeoleptochromus schaufussi 0?21?01111 0–01??0011 10––1?0220 100????0?? ?????????? ??????01?? ?–??????? Leptochromus agilis 0001101011 1001111100 0101100220 0–0000100 1110101000 0110101100 0010000001 Leptochromus laselva 0001101011 1101111100 0101100220 0–0000100 1110101000 0110101100 0010000001 Euroleptochromus sabathi 0001?01011 1101??1100 11011?0220 0–000?10? ??10?0?000 0??0001100 0010?????? Euroleptochromus setifer 0001101011 1101??1100 1101100220 0–0000100 1?1000?000 0??0001100 0010?????? Baltostigus horribilis 0000100010 0–01?1001 001111?122 11101???0? ??????1100 0??0000000 0000?????? Baltostigus antennatus 0000100010 0–01??001 001111?122 11101???0? ?????????0 ???0??0000 ?010?1??01 Baltostigus striatipennis 0000100010 0–0111001 001111?122 11101??00? ??00101100 0??0000000 0010?????? Rovnoleptochromus ableptonoides 0001?0?011 0–01110101 0101100220 0–00???0? ???0?1?001 ???0001000 1010?????? Cretoleptochromus archaicus 0111101011 0–0111011? ?0––10022 01000?000? ??10?0?001 ???1100010 0010?????? Cretoleptochromus burmiticus 0121?0?011 0–01110110 10––1?022 01000?010? ?????????? ?????0001? ?010?1??0? Cretoleptochromus sp. 01111?101? 0–01110111 10––1?0220 1000???0? ?????????0? ??11000?00 010?1??11 ‘–’ indicates inapplicable characters. ‘?’ indicates missing data. View Large APPENDIX 3 Characters and character states included in phylogenetic analysis 0. Modified, broadened and flattened setae on thorax and antennae: (0) absent; (1) present. 1. Setae on frons and vertex: (0) approximately uniform in length; (1) some setae conspicuously long and erect among much shorter and denser basic vestiture. 2. Broadest site of head capsule: (0) near middle; (1) in posterior half; (2) in anterior half. 3. Anterior margin of frons between antennal insertions: (0) subtriangular, distinctly expanded anteriorly at middle; (1) straight or indistinctly arcuate. 4. Frontoclypeal groove: (0) marked only at middle; (1) extending over entire width of head capsule. 5. Median longitudinal groove on vertex: (0) absent; (1) present. 6. Posteromedian impression on vertex: (0) absent; (1) present. 7. Posterior margin of vertex: (0) lacking a pair of enlarged lateral setae or conspicuous chaetopores; (1) with a pair of distinctly enlarged lateral setae, clearly different from surrounding setae, or with a pair of conspicuous chaetopores. 8. Antennal insertions: (0) adjacent to mandibular bases; (1) clearly separated from mandibular bases. 9. Postgenal (subocular) bristles: (0) absent; (1) present. 10. Postgenal process: (0) absent; (1) present. 11. Shape of postgenal process: (0) short, tuberculate; (1) strongly elongate. 12. Compound eyes: (0) large, composed of at least several dozen ommatidia; (1) rudimentary, composed of one to several ommatidia, or absent. 13. Placement of eyes: (0) adjacent to antennal insertions; (1) separated (sometimes narrowly) from antennal insertions. 14. Labrum: (0) with anterior margin straight or arcuate; (1) with anteromedian emargination (sometimes with an additional narrow median projection). 15. Mandible: (0) lacking preapical teeth or, if teeth present, then located strictly mesally in same plane as apical tooth; (1) with at least one preapical tooth located and directed dorsomesally, above plane of mandible. 16. Setal process on maxillary palpomere 2: (0) absent; (1) present. 17. Setae on maxillary palpomere 2: (0) uniform; (1) at least a few remarkably long, erect and often thickened setae or thick bristles on anteroventral surface among shorter and/or suberect or recumbent basic vestiture. 18. Setae on maxillary palpomere 3: (0) uniform; (1) sparse, long and strongly erect setae (often thickened) present among basic recumbent or suberect vestiture. 19. Distal margin of maxillary palpomere 3: (0) approximately perpendicular to long axis of palpomere; (1) distinctly, often strongly, oblique. 20. Relative width of maxillary palpomere 4: (0) broader than 3; (1) narrower than 3. 21. Palpomere 4: (0) narrowing from base to apex; (1) broadening distad, at least in basal half. 22. Broadened palpomere 4: (0) weakly, often only slightly broadened and elongate; (1) strongly broadened, broader than long, axe-shaped. 23. Weakly broadened palpomere 4: (0) curved (i.e. with one side convex and the opposite concave); (1) not curved (i.e. with both sides nearly straight or convex). 24. Maxillary palpomeres 3 + 4: (0) with lateral margins confluent, palpomeres together forming compact oval; (1) with lateral margins not confluent. 25. Insertions of labial palps: (0) broadly separated (by more than maximum width of palpomere 1); (1) approximate (closer together than maximum width of palpomere 1). 26. Distance between antennal insertions: (0) at least twice as wide as antennal cavity; (1) about as wide as antennal cavity or narrower. 27. Length of scape: (0) much shorter than head capsule; (1) about as long as head capsule or slightly longer; (2) much longer than head capsule. 28. Antennae: (0) cannot bend between scape and pedicel; (1) can bend dorsad or dorsolaterad between scape and pedicel; (2) can bend ventrad or ventrolaterad between scape and pedicel. 29. Pedicel: (0) short, not conspicuously enlarged, lacking ventral rows of bristles; (1) strikingly elongated, much longer than subsequent antennomeres and with ventral bristles arranged in rows. 30. Bristles on scape: (0) absent, vestiture of scape relatively uniform; (1) present, strongly erect, long and directed ventrad (slightly or much thicker than basic vestiture of scape). 31. Arrangement of bristles on scape: (0) unordered; (1) ordered in two longitudinal rows. 32. Flagellomeres (except 11): (0) all or nearly all elongate; (1) mostly broader than long or some about as long as broad. 33. Posterior pronotal collar: (0) distinct, demarcated from disc by transverse groove or impressed row of pits and variously distinct constriction; (1) absent. 34. Procoxal cavities: (0) broadly open posteriorly; (1) delimited posteriorly by hypomeral lobes strongly projecting mesad. 35. Procoxal cavities: (0) distinctly demarcated from basisternum by arcuate ridges; (1) anteriorly confluent with basisternum. 36. Basisternal and coxal parts of prosternum: (0) subequal in length; (1) basisternal part much longer (1.5 times and more) than coxal part. 37. Vestiture of basisternal part of prosternum: (0) approximately uniform; (1) composed of two rows of setae extending along anterior and posterior margin and largely or completely asetose in between. 38. Anterior ridge of mesoventrite: (0) with posteromedian subtriangular projection or expansion; (1) lacking posteromedian projection. 39. Posteromedian projection of anterior ridge of mesoventrite: (0) posteriorly connected with mesoventral intercoxal process; (1) posteriorly demarcated from mesoventral intercoxal process. 40. Transverse impression filled with setae on mesoventrite: (0) absent; (1) present. 41. Median region of mesoventrite anterior to mesocoxal cavities: (0) with conspicuously large, evenly and weakly convex area about as long as broad; (1) lacking such area. 42. Mesoventral intercoxal process: (0) slender and narrow, much longer than broad; (1) stout, about as long as broad. 43. Median subtriangular convexity of anterior mesoventral region: (0) present; (1) absent. 44. Lateral margins of mesoventral intercoxal process between mesocoxae: (0) subparallel; (1) convergent posteriorly. 45. Sharp anterior carina of mesocoxal cavities confluent with lateral margin of mesoventral process: (0) present; (1) absent. 46. Posterior margin of mesocoxal cavities: (0) carinate (at least partly); (1) non-carinate. 47. Metaventrite: (0) broadest near posterior third or between middle and posterior third, distinctly narrowing toward metacoxae; (1) broadest at or just in front of metacoxae. 48. Median longitudinal metaventral carina: (0) absent; (1) present. 49. Dorsolateral fovea (i.e. laterad mesepimeron + mesanepisternum and directed mesally): (0) absent; (1) present. 50. Postmesocoxal metaventral fovea (at posterior or posterolateral margin of mesocoxal cavity and directed mesally or anteromesally): (0) absent; (1) present. 51. Fovea at lateral margin of mesocoxal cavity directed anterolaterally: (0) absent; (1) present. 52. Anterior margin of katepisternum: (0) not marked; (1) distinctly marked as arcuate groove extending along lateroanterior margin of metacoxa. 53. Admetacoxal margin of metaventrite: (0) concave, lacking angulate expansion; (1) with angulate expansion. 54. Row of several (3–6) thick bristles (conspicuously thicker than basic vestiture of coxa) on ventral surface of mesocoxa: (0) absent; (1) present. 55. Protrochanteral ventral comb of several (2–7) thick bristles: (0) absent; (1) present. 56. Profemoral ventral comb of several thick bristles: (0) absent; (1) present. 57. One or two conspicuously long and erect ventral setae in basal half of profemur: (0) absent; (1) present. 58. Suture between metaventrite and first visible abdominal sternite: (0) distinct; (1) nearly obliterated, abdominal sternite fused medially with posterior margin of metaventrite. 59. Transverse, broadly and inversely V-shaped median ridge on abdominal sternite 3: (0) absent; (1) present. 60. Elytral disc: (0) with punctures arranged in longitudinal rows or with impressed longitudinal striae; (1) with punctures not arranged in rows. 61. Longitudinal rows of elytral punctures: (0) fine and barely discernible, nearly lost among fine unordered punctures or microsculpture; (1) distinct, composed of conspicuously large punctures, often connected by impressed striae. 62. Basal elytral foveae: (0) absent; (1) present. 63. Median longitudinal impression on propygidium: (0) absent; (1) present. 64. Posterior margin of abdominal sternite 8 in males: (0) distinctly emarginate; (1) rounded or truncate. 65. Flagellum: (0) short and straight or C-shaped, but not looped; (1) very long, forming several loops. 66. Permanently everted membranous apical part of copulatory piece: (0) absent; (1) present. 67. Parameres: (0) symmetrical or nearly symmetrical; (1) asymmetrical, one paramere shorter than the other one. 68. Apices of parameres: (0) abruptly and strongly bent mesally; (1) not bent mesally, at most evenly and slightly curved toward middle. REFERENCES Aitchison JC , Ali JR , Davis AM . 2007 . When and where did India and Asia collide ? Journal of Geophysical Research 112 : doi: 10.1029/2006JB004706 . de Bruyn M , Stelbrink B , Morley RJ , Hall R , Carvalho GR , Cannon CH , van den Bergh G , Meijaard E , Metcalfe I , Boitani L , Maiorano L , Shoup R , von Rintelen T . 2014 . Borneo and Indochina are major evolutionary hotspots for Southeast Asian biodiversity . Systematic Biology 63 : 879 – 901 . Google Scholar CrossRef Search ADS PubMed Cai C-Y , Huang D-Y . 2016 . Cretoleptochromus archaicus gen. et sp. nov., a new genus of ant-like stone beetles in Upper Cretaceous Burmese amber (Coleoptera, Staphylinidae, Scydmaeninae) . Cretaceous Research 63 : 7 – 13 . Google Scholar CrossRef Search ADS Casey TL . 1897 . Coleopterological notices, VII . Annals of the New York Academy of Science 9 : 285 – 684 . Google Scholar CrossRef Search ADS Castellini G . 1996 [1994] . Revisione del genre Leptomastax Pirazzoli, 1855 (Coleoptera, Scydmaenidae) . Atti del Museo Civico di Storia Naturale di Grosseto 15 : 1 – 137 . Endrödy-Younga S . 1978 . Coleoptera . In: Werger MJA , Van Bruggen AC , eds. Biogeography and ecology of Southern Africa . Hague : W. Junk Publishers , 797 – 821 . Google Scholar CrossRef Search ADS Fleming J . 1821 . Insecta. supplement to the fourth, fifth and sixth editions of the encyclopaedia Britannica , Vol. 5[Part 1]. Edinburgh : A. Constable and Company , pp. 41 – 56 . Franz H . 1985 . Revision Caseyscher Scydmaenidentypen . Sitzungsberichte der Österreichischen Akademie der Wissenschaften, Mathematisch-Naturwissenschaftliche Klasse, Abteilung I 194 : 149 – 186 . Frivaldszky J . 1877 . Coleoptera Nova e hungaria meridionale . Természetrajzi Füzetek 1 : 17 – 22 . Goloboff P , Farris J , Nixon K . 2008 . TNT, a free program for phylogenetic analysis . Cladistics 24 : 774 – 786 . Google Scholar CrossRef Search ADS Grebennikov VV , Newton AF . 2009 . Good-bye Scydmaenidae, or why the ant-like stone beetles should become megadiverse Staphylinidae sensu latissimo (Coleoptera) . European Journal of Entomology 106 : 275 – 301 . Google Scholar CrossRef Search ADS Hadley A . 2010 . Combine ZP software, new version, [WWW document] . URL http://www.hadleyweb.pwp.blueyonder.co.uk/CZP/News.htm (currently available at http://combinezp.software.informer.com/) Jałoszyński P . 2012a . Description of Euroleptochromus gen. n. (Coleoptera, Staphylinidae, Scydmaeninae) from Baltic amber, with discussion of biogeography and mouthpart evolution within Clidicini . Systematic Entomology 37 : 346 – 359 . Google Scholar CrossRef Search ADS Jałoszyński P . 2012b . Stenomastigus Leleup (Staphylinidae, Scydmaeninae): status of subgenus Acanthostigus Leleup and revision of species with elongated male protrochanters . Zootaxa 3153 : 39 – 56 . Jałoszyński P . 2012c . Beetles with ‘trochantelli’: phylogeny of Cephenniini (Coleoptera: Staphylinidae: Scydmaeninae) focussing on Neotropical genera . Systematic Entomology 37 : 448 – 477 . Google Scholar CrossRef Search ADS Jałoszyński P . 2016a . Scydmaeninae Leach, 1815 . In: Beutel RG , Leschen RAB , eds. Handbook of zoology, ‘arthropoda: insecta’, coleoptera, beetles. morphology and systematics , Vol. 1 , 2nd edn . Berlin : Walter de Gruyter . Jałoszyński P . 2016b [2015] . A new Eocene genus of ant-like stone beetles sheds new light on the evolution of Mastigini . Journal of Paleontology 89 : 1056 – 1067 . Google Scholar CrossRef Search ADS Jałoszyński P . 2017 . First record of Cephenniini on Christmas Island, with updated checklist of world Cephennomicrus species and summary of their distribution (Coleoptera, Staphylinidae, Scydmaeninae) . Zootaxa 4227 : 593 – 600 . Google Scholar CrossRef Search ADS Jałoszyński P , Hlaváč P , Nomura S . 2003 . Contribution to the knowledge of the genus Clidicus (Coleoptera, Scydmaenidae), with descriptions of four new species from Vietnam and Laos . Bulletin of National Science Museum Tokyo, Ser. A 29 : 21 – 38 . Jałoszyński P , Perkovsky E . 2016 . Diversity of Scydmaeninae (Coleoptera: Staphylinidae) in Upper Eocene Rovno amber . Zootaxa 4157 : 1 – 85 . Google Scholar CrossRef Search ADS PubMed Jałoszyński P , Matsumura Y , Beutel RG . 2015 . Evolution of a giant intromittent organ in Scydmaeninae (Coleoptera: Staphylinidae): functional morphology of the male postabdomen in Mastigini . Arthropod Structure & Development 44 : 77 – 98 . Google Scholar CrossRef Search ADS PubMed Jałoszyński P , Brunke AJ , Metscher B , Zhang W-W , Bai M . 2017a . Clidicostigus gen. nov., the first Mesozoic genus of Mastigini (Coleoptera: Staphylinidae: Scydmaeninae) from Burmese amber . Cretaceous Research 72 : 110 – 116 . Google Scholar CrossRef Search ADS Jałoszyński P , Perrichot V , Peris D . 2017b . Ninety million years of chasing mites by ant-like stone beetles . Gondwana Research 48 : 1 – 6 . Google Scholar CrossRef Search ADS Lacordaire JT . 1835 . In: Boisduval J , Lacordaire , JT , eds. Faune entomologique des environs de Paris: ou species général des insectes qui se trouvent dans un rayon de quinze à vingt lieues aux alentours de Paris . Tome premier. Paris : Méquignon-Marvis , p. 696 . Laporte FL . 1832 . Mémoire sur cinquante espèces nouvelles ou peu connues d’insectes . Annales de la Société Entomologique de France 1 : 386 – 415 . Latreille PA . 1802 . Histoire naturelle, générale et particulière des Crustacés et des Insectes. Familles Naturelles des Genres , Vol. 3 . Paris : F. Dufart , xii + 13 – 467 pp. Leach WE . 1815 . Entomology . In: Brewster D , ed. Brewster’s Edinburgh encyclopedia , Vol. 9[part I]. Edinburgh : W. Blackwood, J. Waugh; London: J. Murray, Baldwin & Cradock, J. M. Richardson; and the other proprietors ., 57 – 172 . Google Scholar CrossRef Search ADS Liu Z , Pagani M , Zinniker D , Deconto R , Huber M , Brinkhuis H , Shah SR , Leckie RM , Pearson A . 2009 . Global cooling during the eocene-oligocene climate transition . Science (New York, NY) 323 : 1187 – 1190 . Google Scholar CrossRef Search ADS Metcalfe I , Smith JMB , Morwood M , Davidson I . 2001 . Faunal and floral migrations and evolution in SE Asia–Australasia . Lisse, Abingdon, Exton, Tokyo : A.A. Balkema Publishers . Maddison WP , Maddison DR . 2017 . Mesquite: a modular system for evolutionary analysis, version 3.2, [WWW document] . URL http://mesquiteproject.org Müller PWI , Kunze G . 1822 . Monographie der Ameisenkäfer (Scydmaenus Latreille) . Schriften der Naturforschenden Gesellschaft zu Leipzig 1 : 175 – 204 . Nixon KC . 1999–2002 . WINCLADA (Beta), 1.00.08. Software published by the author, Ithaca, New York. [WWW document] . URL http://www.cladistics.com (currently available at http://www.diversityoflife.org/winclada/) O’Keefe ST . 1998 . Notes on the classification of North American ant-like stone beetles (Coleoptera: Scydmaenidae) . The Coleopterists Bulletin 52 : 259 – 269 . O’Keefe ST . 2002 . Revision of the Neotropical genus Leptochromus Motschulsky (Coleoptera: Scydmaenidae) . Systematic Entomology 27 : 211 – 234 . Google Scholar CrossRef Search ADS O’Keefe ST . 2003 . Revision of the Nearctic genus Papusus Casey (Coleoptera, Scydmaenidae) . In: Cuccodoro G. , Leschen RAB , eds. Systematics of Coleoptera: papers celebrating the retirement of Ivan Löbl . Gainsville: Memoirs on Entomology International, Associated Publishers 17 : 257 – 309 . O’Keefe ST , Pike T , Poinar G . 1997 . Palaeoleptochromus schaufussi (gen. n., sp. nov.), a new antlike stone beetle (Coleoptera: Scydmaenidae) from Canadian Cretaceous amber . The Canadian Entomologist 129 : 379 – 385 . Google Scholar CrossRef Search ADS Orousset J . 2014 . Contribution à la connaissance du genre Clidicus Laporte de Castelnau, 1832 (Coleoptera, Staphylinidae, Scydmaeninae) . Le Coléoptériste 17 : 116 – 135 . Page RDM . 2001 . NDE: NEXUS Data Editor 0.5.0. University of Glasgow, Glasgow, Scotland, UK [WWW document] . URL http://taxonomy.zoology.gla.ac.uk/rod/NDE/nde.html Pascoe FP . 1866 . Notice on new or little known genera and species of Coleoptera, Part IV . Journal of Entomology 2 : 26 – 56 . Rambaut A , Suchard MA , Xie D , Drummond AJ . 2014 . Tracer v.1.6 457http://beast.bio.ed.ac.uk/Tracer Reitter E . 1890 . Neue Coleopteren aus Europa, den angrenzenden Ländern und Sibirien, mit Bemerkungen über bekannte Arten. Elfter Theil . Deutsche Entomologische Zeitschrift 34 : 385 – 396 . Ronquist F , Teslenko M , Van Der Mark P , Ayres DL , Darling A , Höhna S , Larget B , Liu L , Suchard MA , Huelsenbeck JP . 2012 . MrBayes 3.2: efficient Bayesian phylogenetic inference and model choice across a large model space . Systematic Biology 61 : 539 – 542 . Google Scholar CrossRef Search ADS PubMed Sharp D . 1874 . Descriptions of new genera and species of Pselaphidae and Scydmaenidae from Australia and New Zealand . Transactions of the Entomological Society of London 1874 : 483 – 517 . Whiting MF , Bradler S , Maxwell T . 2003 . Loss and recovery of wings in stick insects . Nature 421 : 264 – 267 . Google Scholar CrossRef Search ADS PubMed Yin Z , Cai C , Huang D , Li L . 2017a . A second species of the genus Cretoleptochromus Cai & Huang (Coleoptera: Staphylinidae: Scydmaeninae) from mid-Cretaceous Burmese amber . Cretaceous Research 75 : 115 – 119 . Google Scholar CrossRef Search ADS Yin ZW , Cai CY , Huang DY , Li LZ . 2017 . Specialized adaptations for springtail predation in Mesozoic beetles . Scientific Reports 7 : 98 . Google Scholar CrossRef Search ADS PubMed Yu Y , Harris AJ , He X . 2010 . S-DIVA (Statistical Dispersal-Vicariance Analysis): a tool for inferring biogeographic histories . Molecular Phylogenetics and Evolution 56 : 848 – 850 . Google Scholar CrossRef Search ADS PubMed Yu Y , Harris AJ , Blair C , He X . 2015 . RASP (Reconstruct Ancestral State in Phylogenies): a tool for historical biogeography . Molecular Phylogenetics and Evolution 87 : 46 – 49 . Google Scholar CrossRef Search ADS PubMed Żyła D , Yamamoto S , Wolf-Schwenninger K , Solodovnikov A . 2017 . Cretaceous origin of the unique prey-capture apparatus in mega-diverse genus: stem lineage of Steninae rove beetles discovered in Burmese amber . Scientific Reports 7 : doi: 10.1038/srep45904 © 2018 The Linnean Society of London, Zoological Journal of the Linnean Society This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices) http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Zoological Journal of the Linnean Society Oxford University Press

Evolution of Mastigitae: Mesozoic and Cenozoic fossils crucial for reclassification of extant tribes (Coleoptera: Staphylinidae: Scydmaeninae)

Loading next page...
 
/lp/ou_press/evolution-of-mastigitae-mesozoic-and-cenozoic-fossils-crucial-for-VfJoGUNSjQ
Publisher
The Linnean Society of London
Copyright
© 2018 The Linnean Society of London, Zoological Journal of the Linnean Society
ISSN
0024-4082
eISSN
1096-3642
D.O.I.
10.1093/zoolinnean/zly010
Publisher site
See Article on Publisher Site

Abstract

Abstract Mastigitae is a supertribe of ant-like stone beetles (Scydmaeninae) that includes over 40% extinct genera, and whose evolutionary history is documented from the Upper Cretaceous through to today. Based on the results of phylogenetic analyses combining the most extensive taxon sampling to date, we reclassify Mastigitae into six monophyletic units: Leptomastacini, Clidicini sensu nov., Papusini trib. nov., Leptochromini trib. nov., †Baltostigini trib. nov. and Mastigini sensu nov. †Cretoleptochromus is placed as a junior synonym of Clidicus, and †Cascomastigus as a junior synonym of †Clidicostigus. Euroleptochromus setifer sp. nov. and Baltostigus striatipennis sp. nov. are both described from Upper Eocene Baltic amber. We postulate that Mastigitae have undergone differentiation into major lineages before the Cenomanian and that the Eurasian part of Laurasia was their ancestral distribution area. The reconstructed ancestor of Mastigitae was similar to the extant Scydmaenini, but with broadly separated antennal insertions and deep elytral striae. Four independent wing losses were inferred in Mastigitae. We present the first complete μCT reconstruction of the aedeagus in a fossilized scydmaenine, crucial for understanding the more than 99 million year long evolution of one of the most bizarre, asymmetrical aedeagi in the Coleoptera. beetle, Cretaceous, Eocene, male genitalia phylogeny, taxonomy INTRODUCTION Mastigitae is one of three currently recognized supertribes within the extant ant-like stone beetles (Staphylinidae: Scydmaeninae). It comprises three tribes, Clidicini, Leptomastacini and Mastigini, with nine extant genera and 126 extant species (Jałoszyński, 2016a). Fossils, including seven extinct genera, have been described from Cenomanian, Campanian, Priabonian and Miocene/Oligocene amber (summarized by Jałoszyński & Perkovsky, 2016 and Jałoszyński et al., 2017a). Among the scydmaenines, Mastigitae species show an unusually broad spectrum of morphological structures (examples of extant and extinct forms are shown in Figure 1) and ecological adaptations. For these reasons, they attract much attention. Mastigitae include the largest adult beetles among the Scydmaeninae, reaching 1 cm of body length and dwarfing most others of the subfamily, which do not exceed 2 mm and often do not reach 1 mm. Extant species of Clidicini include small (∼1.6–3 mm), flattened and lightly pigmented beetles that live under stones in the most arid deserts of North America and large (up to 1 cm), darkly pigmented and strongly convex beetles associated with leaf litter in humid Oriental, Australian and Neotropical forests (Fig. 1A). One genus, placed as incertae sedis, but possibly closely related to Clidicini, was recently found in Cenomanian Myanmar amber (Fig. 1B); other extinct forms are known from the Campanian of Canada, the Upper Eocene of north-central Europe (Fig. 1C, D) and the Miocene/Oligocene of Chiapas, Mexico (O’Keefe et al., 1997; O’Keefe, 2002; Jałoszyński, 2012a; Jałoszyński & Perkovsky, 2016; Cai & Huang, 2016; Yin et al., 2017a). Extant Mastigini are long-legged beetles with a conspicuously enlarged and spiny scape and pedicel; they have diurnal adults that often live in dense populations and run on the ground or climb bushes and trees. The recently discovered Cenomanian †Clidicostigus Jałoszyński et al. and †Cascomastigus Yin & Cai from Myanmar amber had a monstrously enlarged scape and pedicel and enormously long legs (Fig. 1E), and were presumably wingless, like their extant European and South African relatives (Jałoszyński et al., 2017a; Yin et al., 2017b). However, Upper Eocene north-European †Baltostigus Jałoszyński (Fig. 1F), currently classified in this tribe, had large, functional wings, and its body shape was conspicuously stout and small, unlike that of any other Mastigini. Some extant Mastigini show uniquely modified male genitalia, with the aedeagus so enlarged that it cannot be retracted into the male’s abdomen in repose (Jałoszyński et al., 2015). They have evolved a mating mechanism not known in any other beetles, in which one strongly elongate paramere (the other one is vestigial or obliterated) is inserted into the female’s subelytral space (Jałoszyński et al., 2015). An asymmetrical aedeagus was also found in the Upper Cretaceous †Clidicostigus, raising questions related to the unique origin of asymmetrical genitalia in the Mastigini. Finally, species of Mediterranean and Carpathian Leptomastacini are small (1.1–3 mm long) beetles, typically depigmented, flattened, microphthalmous or blind and inhabit deep soil layers (e.g. Castellini, 1996). Fossils of Leptomastacini remain unknown. Figure 1. View largeDownload slide Examples of extant and extinct Mastigitae. A, Clidicus formicarius (Borneo). B, †Cretoleptochromus archaicus (Cenomanian of Myanmar). C, †Euroleptochromus sabathi (Eocene of Lithuania). D, †Rovnoleptochromus ableptonoides (Eocene of Ukraine). E, †Clidicostigus arachnipes (Cenomanian of Myanmar). F, †Baltostigus antennatus (Eocene of Poland). B–F, artistic reconstructions based on the respective holotype specimens. Scale bars: 2 mm. Figure 1. View largeDownload slide Examples of extant and extinct Mastigitae. A, Clidicus formicarius (Borneo). B, †Cretoleptochromus archaicus (Cenomanian of Myanmar). C, †Euroleptochromus sabathi (Eocene of Lithuania). D, †Rovnoleptochromus ableptonoides (Eocene of Ukraine). E, †Clidicostigus arachnipes (Cenomanian of Myanmar). F, †Baltostigus antennatus (Eocene of Poland). B–F, artistic reconstructions based on the respective holotype specimens. Scale bars: 2 mm. The Mastigitae show a puzzling distribution, with wide geographic disjunctions within its tribes, and even within genera such as Palaeostigus Newton (Mastigini), which occurs in Southern Europe and South Africa (Fig. 2). This distribution posed puzzling biogeographic problems for previous researchers; for instance, the ‘bipolar’ western Palaearctic and southern African distribution of Mastigini was interpreted by Endrödy-Younga (1978) as evidence for Pangean origins of this tribe, and, later, Castellini (1996) suggested central Africa as the source of the present-day diversity and distribution of Mastigitae, with ancestors of Mastigini dispersing southward into South Africa, and northward into Europe during the Lower Cretaceous. The latter author entirely omitted the New World taxa from his discussion. O’Keefe (2002) carried out a phylogenetic analysis with only four genera, including one extinct species, and hypothesized a single split between Clidicini in Eurasian and American parts of Laurasia before or during the Cretaceous. This author, in turn, omitted South African taxa. Jałoszyński (2012a) included in his phylogenetic analysis nearly all genera (extant and extinct) unambiguously placed in the Mastigitae at that time, including a newly discovered Upper Eocene genus †Euroleptochromus Jałoszyński, proposed Laurasia as the ancestral area for this supertribe and explained the puzzling distribution of extant Mastigini as being the result of one of the youngest events in the biogeography of Mastigitae – a dispersal from Europe to South Africa. The subsequent discovery of another, new Upper Eocene genus, †Baltostigus Jałoszyński, placed in Mastigini, and the addition of the poorly known extant genus Taurablepton Franz, resulted in further support for the Laurasian (or Eurasian) hypothesis (Jałoszyński, 2016b). Figure 2. View largeDownload slide Distribution of Mastigitae (divided into tribes in the traditional sense). Figure 2. View largeDownload slide Distribution of Mastigitae (divided into tribes in the traditional sense). The recent accumulation of novel morphological and spatiotemporal data from newly discovered fossils of Mastigitae, allows for a new approach to the phylogeny of this interesting group. †Cretoleptochromus Cai & Huang was placed as incertae sedis and its placement requires clarification. †Cascomastigus seems to be identical with †Clidicostigus and placement of some extant genera (e.g. Papusus Casey) remained unresolved in any hitherto published phylogenetic reconstructions. Apart from newly discovered fossils, knowledge of character variability within large extant genera has recently improved considerably (e.g. Jałoszyński, 2012b; Orousset, 2014), and the previously unknown male of the enigmatic extant Turkish genus Taurablepton was discovered and made available for this study. These new data prompted us to revisit phylogenetic hypotheses of evolutionary relationships within Mastigitae, and to reconstruct ancestral character states and ancestral distribution areas. Apart from general long-standing problems, such as the currently problematic tribal classification, we also address the question of when the conspicuously asymmetrical male genitalia in Mastigini evolved. MATERIAL AND METHODS Specimen handling, imaging and measurements Species representing all genera placed unambiguously in Mastigitae were studied, including nine extant and seven extinct genera represented by 25 species. For three species, characters were extracted from original descriptions and illustrations. A list of taxa, examination methods and depositories are given in Appendix 1. Aenictosoma Schaufuss and Palaeomastigus Schaufuss, genera presumably belonging in or putatively assigned to Mastigitae, were described in an inadequate way and depositories of their type specimens remain unknown (presumably lost or destroyed during WWII); these taxa were excluded from our study. Two extant species of Clidicus Laporte were included in the analysis to represent two morphological groups within this genus, i.e. large-bodied beetles with strongly elongate antennomeres and very long maxillary palps and legs (C. formicarius), and small-bodied beetles with weakly elongate antennomeres, stout palps and relatively short legs (C. bellator); two species of Leptochromus Motschulsky were selected to represent forms with a short (L. agilis) and long (L. laselva) postgenal process; two species of Palaeostigus Newton were selected to represent the Palaearctic (P. ruficornis) and South African (P. bifoveolatus) groups. Specimens of extinct Mastigitae were studied as amber inclusions under Nikon SMZ1500 (Nikon, Tokyo, Japan) and Leica M205C (Leica Microsystems, Wetzlar, Germany) stereomicroscopes, submersed in cedar oil to improve visibility. Photographs were taken using a KYF75U digital camera (JVC, Yokohama, Japan) mounted to a Leica microscope. Image stacks were processed using COMBINEZP (Hadley, 2010). Extant taxa were studied as intact dry-mounted specimens under stereomicroscopes, as intact temporary whole-body mounts in glycerol or disarticulated permanent slides in Canada balsam under a Nikon Eclipse Ni compound microscope, or as uncoated intact specimens with a Helios Nanolab 450HP scanning electron microscope (FEI, Hillsboro, USA) (examination method for each species is given in Appendix 1). Morphological structures were figured by freehand drawing, with exact proportions and general shapes sketched from photographs. Measurement convention and the terminology of morphological structures follow those of Jałoszyński (2012a) Elytral index and pronotal index are the length of respective body part divided by its width. MicroCT imaging of amber inclusions was performed at the Department of Theoretical Biology, University of Vienna, using a Zeiss/Xradia MicroXCT-200 system with a tungsten X-ray source set at 60 kVp, with no beam filter and exposure time of 5 (Baltostigus striatipennis), 10 (Euroleptochromus setifer) or 30 s (Baltostigus antennatus) per projection. The sample was imaged at 4× (E. setifer and B. striatipennis) or 10× (B. antennatus) magnification. Image contrast benefited from propagation phase contrast in all cases. Tomographic sections were reconstructed with an isotropic voxel size of 4.0 μm (E. setifer and B. striatipennis) or 1.0 μm (B. antennatus) using the Xradia Recon software. Segmentation was accomplished in AMIRA 6.0.1 (https://www.fei.com/software/amira-for-life-sciences/), while volume rendering was performed in either AMIRA or DRISHTI 2.6.3 (https://sf.anu.edu.au/Vizlab/drishti/). The archive links for reconstructed images are as follows: http://phaidra.univie.ac.at/o:683387; http://phaidra.univie.ac.at/o:683388; and http://phaidra.univie.ac.at/o:683389. The distribution map (Fig. 2) is based on an image obtained from the Demis World Map Server open source (http://webmap.iwmi.org/DataSrc.htm). All images were edited and assembled in plates with Corel PhotoPaint 9.397. Phylogenetic analysis The analysis was based on a previously published data matrix (Jałoszyński, 2012a, 2016b), which was modified to include more characters (especially those related to genital structures and to accommodate new knowledge of the character variability within extant genera) and most recently discovered genera and species. The in-group taxa comprised representatives of all known extant and extinct genera of Mastigitae. The outgroup taxa included three genera of Scydmaenini, a tribe previously found to be the sister-group of Mastigitae (Jałoszyński, 2012c), and Euaesthetus Gravenhorst, 1806, a member of Euaesthetinae, a subfamily that, together with Steninae, forms a clade previously proposed to be the sister-group of Scydmaeninae (Grebennikov & Newton, 2009; Żyła et al., 2017). Phylogenetic analysis was based on 69 (numbered from 0) non-additive and unordered adult morphological characters; inapplicable character states were assigned a gap value (‘–’) and treated equivalent to missing data (‘?’). The data matrix was assembled in NEXUS DATA EDITOR for Windows v.0.5.0 (Page, 2001). The data matrix is presented in Appendix 2; the character list and states are given in Appendix 3. Parsimony analysis was conducted in TNT (Goloboff et al., 2008) under equal weights and using implied weighting (at the weighting function K ranging from 3 to 12) using the ‘traditional search’ strategy; the analysis was rooted with Euaesthetus. The tree bisection reconnection swapping algorithm was applied, with 1000 replicates and 1000 trees saved per replication. Standard bootstrap analysis (1000 replicates) was also conducted in TNT, and character mapping was performed in WINCLADA v.1.00.08 (Nixon, 1999–2002). Trees were exported from WINCLADA and annotated in COREL DRAW 9. The Bayesian analysis was conducted using MRBAYES v.3.2.6 (Ronquist et al., 2012) on the CIPRES Science Gateway v.3.3 (phylo.org), with four chains of two runs each. The Mkv model of character evolution was used with a gamma distribution, to allow for variation in the rate of evolution between characters, considered to be more realistic given the wide range of variability seen between morphological structures. Default settings were used, except for ‘temp = 0.05’ to improve mixing of the chains. Convergence was assessed in TRACER v.1.6.0 (Rambaut et al., 2014) and using PSRF and average standard deviation of split frequencies values in the MRBAYES output. Nodes resolved in the majority rules consensus trees with bootstrap <55 (Parsimony) or PP < 0.70 were considered unsupported. Reconstruction of ancestral character states was carried out in MESQUITE v.3.2 (Maddison & Maddison, 2017), using the 50% majority rule consensus tree obtained in the parsimony analysis under implied weights at the weighting function K = 3. This tree, as better resolved than the results of the Bayesian analysis, was chosen as representing the best available hypothesis for character and biogeographical analyses. The wing character states were not included in the dataset, as the absence or presence of wings in those fossils that do not have exposed wings is only presumed. Therefore, the evolution of winglessness was not reconstructed, but inferred on the basis of tree topologies, i.e. if an ancestral lineage split into winged and wingless taxa, we assume that the ancestor was winged, and the split was followed by loss of wings in one or more of the offspring taxa, instead of chosing an alternative hypothesis that the ancestor was wingless and the wings re-developed in some of the descendent taxa. Biogeographic reconstructions In order to reconstruct the history of biogeographic distributions of Mastigitae, statistical dispersal-vicariance (S-DIVA) analysis and Bayesian Binary Markov Chain Monte Carlo (BBM) Analysis were carried out, using the RASP program (Yu et al., 2010, 2015). The distribution of studied taxa was divided into five recent regions: Eurasia, South Africa, North America, Central and South America, and Australia. In S-DIVA, the maximum areas to each node were restricted to two; the ‘allow reconstruction’ option was switched on. In BBM, the ancestral range of the root was considered too wide to be useful and, consequently, the root distribution was set at ‘wide’ (i.e. the virtual outgroups assigned to the phylogenetic tree prior to the start of an analysis coded to occur in all areas occupied by the in-group); the JC model was selected and the default number of cycles (50000; sufficient to obtain the difference between run 1 and 2 <0.01), chains (10), frequency of samples (100), samples discarded (100) and temperature (0.1) were used. Two separate analyses were run, with two and five maximum areas allowed in ancestral distribution of each node. RESULTS Phylogeny The traditional search run of TNT under equal weights resulted in 105 most parsimonious trees; re-analysis under implied weights (at all tested weighting functions) resulted in only 15 most parsimonious trees (tree length, L = 136; consistency index, CI = 0.52; retention index, RI = 0.82); and in each of them the same six major clades within Mastigitae were resolved as in the unweighted analysis (Fig. 3, clades A–F). Differences were restricted to relationships between terminal taxa within clades B, E and F. In the 50% majority rule consensus tree (Fig. 3), some relationships within these three clades remained unresolved. Optimized apomorphies are shown on one of the shortest trees from the parsimony analysis under implied weights and K = 3.000 (Fig. 4). Figure 3. View largeDownload slide Results of the parsimony analysis of the phylogenetic relationships within Mastigitae. 50% majority rule consensus of 15 most parsimonious trees (L = 136; CI = 0.52; RI = 0.82) obtained under implied weighting and K = 3.000. The trees were rooted on Euaesthetus. Standard bootstrap support values >50 are shown above branches and ancestral areas reconstructed in S-DIVA are mapped on the tree. Figure 3. View largeDownload slide Results of the parsimony analysis of the phylogenetic relationships within Mastigitae. 50% majority rule consensus of 15 most parsimonious trees (L = 136; CI = 0.52; RI = 0.82) obtained under implied weighting and K = 3.000. The trees were rooted on Euaesthetus. Standard bootstrap support values >50 are shown above branches and ancestral areas reconstructed in S-DIVA are mapped on the tree. Figure 4. View largeDownload slide Results of the parsimony analysis of the phylogenetic relationships within Mastigitae. One of 15 most parsimonious trees with unambiguously optimized character changes plotted along the internodes. Black circles indicate unique character changes; white circles indicate parallelisms or reversals; character numbers are above circles; character states are below circles. Figure 4. View largeDownload slide Results of the parsimony analysis of the phylogenetic relationships within Mastigitae. One of 15 most parsimonious trees with unambiguously optimized character changes plotted along the internodes. Black circles indicate unique character changes; white circles indicate parallelisms or reversals; character numbers are above circles; character states are below circles. The backbone of the resultant tree (Fig. 3) is poorly supported or unsupported by bootstraps, with the entire Mastigitae (comprising clades A–F) and three consecutive nodes receiving bootstrap values <50. Each of the major clades A, B and D–F (clade C constitutes only one genus, Papusus) was supported by bootstrap values 55–99, with the lowest support for clades containing the highest number of extinct species, and consequently the highest number of missing character states (clades B, D, E and F). The multiple runs of the Bayesian analysis converged far before 10 million generations; at the end of the analysis, all PRSF values were approaching 1.000 and the average standard deviation of split frequencies reached 0.004. Clades A, B, D and E+F were resolved in Bayesian analysis (50% majority rule tree shown in Supporting Information, Figure S1), with posterior probability (PP) = 0.91–1. The Mastigitae in the Bayesian analysis were well supported by PP = 0.87, but the major clades formed an unresolved polytomy; also the three species of Baltostigus formed a polytomy with clade F of the parsimony tree. As the sister-group relationships between the major clades of Mastigitae were better resolved in the weighted parsimony analysis, its results are here presented as a phylogenetic hypothesis, with discussion of differences in relation to the Bayesian results. The monophyly of Mastigitae is supported by six apomorphies (character number and states in brackets): antennal cavities clearly separated from mandibular bases [8(1)]; labrum with anteromedian emargination [14(1)] (shared with some Scydmaenini and reversed in some Clidicus); scape at least as long as head capsule [27(1)] (in some Mastigitae scape much longer than head); posteromedian projection of anterior mesoventral ridge posteriorly demarcated from mesoventral intercoxal process [39(1)]; mesoventrite with transverse impression filled with setae [40(1)] (reversed in Mastigus and Stenomastigus); and elytral disc with punctures arranged in longitudinal rows or with impressed longitudinal striae [60(0)]. The latter character state is difficult to observe in extant Mastigini, whose elytra appear smooth or uniformly covered with microgranules. However, in each species of Mastigus, Palaeostigus and Stenomastigus, fine and shallow striae are present, best visible in the two former genera, in Stenomastigus often obscured by microsculpture. Clade A, composed of all genera traditionally placed in Leptomastacini, was placed as an unsupported sister to all remaining Mastigitae in the parsimony analysis; its placement in the Bayesian consensus tree remained unresolved. This clade was strongly supported (bootstrap = 99; PP = 1) and its components share the following nine apomorphies: thorax and antennae with modified, broadened and flattened setae [0(1)]; posterior margin of vertex with a pair of distinctly enlarged lateral setae, clearly different from surrounding setae, or with a pair of conspicuous chaetopores [7(1)] (shared only with Palaeoleptochromus); compound eyes vestigial or absent [12(1)] (shared with some Scydmaenini); maxillary palpomeres 3 and 4 together forming a compact oval with lateral margins confluent [24(0)]; vestiture of basisternal part of prosternum composed of two rows of setae extending along anterior and posterior margin [37(1)]; postmesocoxal metaventral fovea present [50(1)] (shared with Leptochromus); anterolaterally directed fovea at lateral margin of mesocoxal cavity present [51(1)] (shared with Leptochromus); mesocoxa with a ventral row of several (3–6) thick bristles conspicuously thicker than basic vestiture of coxa [54(1)] (shared with Papusus); and apices of parameres abruptly and strongly bent mesally [68(0)]. Also, all Leptomastacini are lightly pigmented, small (1.1–2.89 mm) and wingless. Fossils of this interesting, presumably subterranean, group of Scydmaeninae, remain unknown. Clidicus, †Cretoleptochromus and †Palaeoleptochromus were resolved as components of clade B, very weakly supported in the parsimony analysis by a bootstrap value of 55, but strongly supported in the Bayesian analysis by PP = 0.93. In the parsimony analysis, this clade was placed (unsupported) as sister to all Mastigitae except for Leptomastacini; in the Bayesian consensus tree, it was sister to clade D (composed of †Rovnoleptochromus, Leptochromus and †Euroleptochromus) but this position was also unsupported (PP = 0.59). Clade B is supported by the following apomorphies: some setae on frons and vertex conspicuously long and erect among much shorter and denser basic vestiture [1(1)]; at least a few remarkably long, erect and often thickened setae or thick bristles located on anteroventral surface of maxillary palpomere 2 among shorter and/or suberect or recumbent basic vestiture [17(1)] (shared with clade D); posterior pronotal collar present [33(0)] (shared with clade D); admetacoxal margin of metaventrite with an angulate expansion [53(1)] (shared with clade F and Leptochromus); and one or two conspicuously long and erect ventral setae present in basal half of profemur [57(1)]. Taxa included in this tribe are so similar to one another that they all may constitute a single genus (see Reclassification of Mastigitae section below). Papusus (clade C) in the parsimony analysis was placed in an unsupported position as sister to clades D + (E+F); placement of this problematic genus in the Bayesian consensus tree was unresolved but it was never included in clades A, B, D, F or E+F. Papusus is defined by one unique apomorphy: conspicuously large eyes that occupy half of the head length, making the tempora much shorter than eyes; in all remaining Mastigitae the eyes are small, located in the anterior portion of the head capsule and the tempora are longer than the eyes. Clade D is composed of extant Leptochromus and extinct †Rovnoleptochromus and †Euroleptochromus; it is weakly supported by a bootstrap value of 67, but well-supported in the Bayesian analysis, by PP = 0.91. In the parsimony analysis, this group was placed as an unsupported sister to the Mastigini (in the traditional sense, i.e. including †Baltostigus); in the Bayesian consensus tree, clade D was placed as an unsupported sister to clade B (i.e. Clidicus and the like). Clade D taxa share the following apomorphies: postgenal bristles present [9(1)] (shared with some members of clade B); at least a few remarkably long, erect and often thickened setae or thick bristles on anteroventral surface of maxillary palpomere 2 among shorter and/or suberect or recumbent basic vestiture [17(1)] (shared with some members of clades B and F); posterior pronotal collar [33(0)] (shared with clade B); and a unique protrochanteral ventral comb of several (2–7) thick bristles [55(1)]. Additionally, Neotropical Leptochromus also shares with European †Rovnoleptochromus and †Euroleptochromus a conspicuously similar body shape with a strongly transverse head capsule. Within clade D, both parsimonious and Bayesian results placed †Rovnoleptochromus as the sister-group of †Euroleptochromus + Leptochromus; the sister relationship between †Euroleptochromus and Leptochromus was supported by bootstrap 89, PP = 0.98, and three unique apomorphies: postgenal process present [10(1)]; setal process present on maxillary palpomere 2 [16(1)]; and profemoral ventral comb of several thick bristles present [56(1)]. All extant Mastigini, †Baltostigus, †Clidicostigus and †Cascomastigus, were resolved as a monophyletic unit in both parsimony and Bayesian analyses, weakly supported by bootstrap (63) but strongly by PP (0.99) values. Relationships within this group were poorly resolved in the Bayesian analysis; parsimony analysis resolved two moderately supported clades, E and F (bootstraps 78 and 74, respectively). In the Bayesian analysis, the clade composed of Stenomastigis, Mastigus Palaeostigus, †Clidicostigus and †Cascomastigus (= F in the parsimony tree) was strongly supported by PP = 1. Clade E is composed of all †Baltostigus species, which are known from the Eocene of Europe, and clade F includes all remaining extant and extinct Mastigini (in the traditional sense). Clade F is well-supported by nine apomorphies (four unique): frontoclypeal groove marked only at middle [4(0)] (shared with the outgroup taxa and Leptomastacini); median longitudinal groove on vertex present [5(1)]; eyes adjacent to antennal insertions [13(0)] (shared only with Scydmaenus); mesoventral intercoxal process stout, about as long as broad [42(1)]; lateral margins of mesoventral intercoxal process between mesocoxae convergent posteriorly [44(1)] (shared with the outgroup, Leptomastacini and †Rovnoleptochromus); metaventrite broadest at or just in front of metacoxae [47(1)]; admetacoxal margin of metaventrite with angulate expansion [53(1)] (shared with clade B and Leptochromus); suture between metaventrite and first visible abdominal sternite nearly obliterated, abdominal sternite medially fused with posterior margin of metaventrite [58(1)]; and parameres asymmetrical, one paramere shorter than the other [67(1)] (possibly shared with some †Cretoleptochromus, but variable also within extant Clidicus; character state not known for †Cascomastigus monstrabilis). Clade E, composed of †Baltostigus, shares most synapomorphies with its sister-group, i.e. clade F, and is supported by an absent posteromedian impression on vertex [6(0)], maxillary palpomere 3 with sparse, long and strongly erect setae present among basic recumbent or suberect vestiture [18(1)] (shared with some members of clade B) and a strongly broadened maxillary palpomere 4 [22(1)]. Ancestral character states Reconstruction of ancestral character states was carried out in accordance with the phylogenetic hypothesis adopted here (Fig. 3). Character states reconstructed for the ancestor of Mastigitae are listed in Supporting Information, Appendix S1. Taxonomically, the most important character states of this hypothetical ancestor are: the vertex lacking median longitudinal groove [5(0)] and posteromedian impression [6(0)]; posterior margin of vertex lacking a pair of enlarged setae [7(0)]; head capsule unmodified, lacking postgenal bristles [9(0)] and postgenal process [10(0)], but with large compound eyes [12(0)]; labrum with anteromedian emargination [14(1)]; maxillary palpomeres 2 and 3 lacking modifications and covered with setae of uniform length [16(0], [17(0)], [18(0)]; maxillary palpomere 4 narrower than 3 [20(1)] and narrowing from base to apex [21(0)]; scape as long as head or longer [27(1)], lacking bristles [30(0)]; pedicel short and lacking bristles [29(0)]; antennae capable of bending ventrally or ventrolaterally between scape and pedicel [28(2)]; pronotum lacking posterior collar [33(1)]; mesoventral intercoxal process slender and narrow [42(0)]; posterior margin of mesocoxal cavities carinate [46(0)]; mesocoxae, protrochanters and profemora lacking thick bristles [54(0)], [55(0)], [56(0)]; elytra with rows of punctures or longitudinal striae [60(0)] and lacking basal foveae [62(0)]. The reconstruction of genital characters, although possible only to a limited extent due to incompleteness of data related to fossils, gave the following results: abdominal sternite 8 in males unmodified, rounded or truncate posteriorly [64(1)]; flagellum straight or C-shaped, not looped [65(0)]; copulatory piece not permanently everted [66(0)]; parameres symmetrical or nearly symmetrical [67(0)], with apices not abruptly bent mesally [68(1)]. Ancestral distribution areas Optimization of the ancestral distributions on the consensus phylogenetic trees using the S-DIVA analysis resulted in a nearly unambiguous reconstruction (Fig. 3; complete results given in Supporting Information, Appendix S2). The supertribe Mastigitae appears to have originated in the Eurasian part of Laurasia, with subsequent dispersals to the North American part of Laurasia (†Palaeoleptochromus), Australia (Clidicus) and South Africa (Palaeostigus), and origination of Papusini + (Leptochromini + (†Baltostigini + Mastigini)) in Laurasia. Clades of eastern Laurasian (Eurasian) origins are Clidicini + (Papusini + (Leptochromini + (†Baltostigini + Mastigini))); Leptochromini + (†Baltostigini + Mastigini); and †Baltostigini + Mastigini. Results of the Bayesian BBM analysis were more ambiguous (Supporting Information, Appendix S2). In the analysis with two ancestral areas allowed for each node, the most probable scenarios were: †Baltostigini + Mastigini originated in the Eurasian part of Laurasia (83.08%); Leptochromini + (†Baltostigini + Mastigini) in the Eurasian + North American parts of Laurasia (66.90%); Papusini + (Leptochromini + (†Baltostigini + Mastigini)) in Eurasian + North American parts of Laurasia (66.44%); Clidicini + (Papusini + (Leptochromini + (†Baltostigini + Mastigini))) in Eurasian + North American parts of Laurasia (86.15%); and Mastigitae in Eurasian + North American parts of Laurasia (65.70%). Increasing the allowed ancestral areas for each node to five resulted in the same scenarios for most of the clades: †Baltostigini + Mastigini originated in Eurasian part of Laurasia (84.13%); Leptochromini + (†Baltostigini + Mastigini) in Eurasian + North American parts of Laurasia (57.08%); Papusini + (Leptochromini + (†Baltostigini + Mastigini)) in Eurasian + North American parts of Laurasia (66.35%); Clidicini + (Papusini + (Leptochromini + (†Baltostigini + Mastigini))) in Eurasian + North American parts of Laurasia + Australia (45.55%); and Mastigitae in Eurasian + North American parts of Laurasia + Australia (27.36%). TAXONOMY Staphylinidae Latreille, 1802 Scydmaeninae Leach, 1815 Mastigitae Fleming, 1821 Clidicini Casey, 1897 sensu nov. Type genus: Clidicus Laporte, 1832. Diagnosis Clidicini, restricted here to Clidicus and †Palaeoleptochromus (which may be a synonym of the former), are defined by the following unique apomorphies: some setae on frons and vertex conspicuously long and erect among much shorter and denser basic vestiture, and one or two conspicuously long and erect ventral setae present in basal half of profemur; and a set of synapomorphies (known in other tribes, but in a different combination): only scape enlarged and longer than head; head capsule about as long as broad or slightly transverse; antennal insertions broadly separated; occipital constriction about half as broad as width of head or narrower; eyes small, much shorter than tempora; maxillary palpomere 4 subtriangular; pronotum with posterior collar separated by transverse row of pits; mesoventral intercoxal process narrow, carinate, with subparallel lateral margins; admetacoxal margin of metaventrite with an angulate expansion; elytral rows of punctures distinct; abdominal sternite 6 not emarginate. Clidicus Laporte, 1832 = †Cretoleptochromus Cai & Huang, 2016 syn. nov. Remarks Clidicus comprises 27 species distributed in Sri Lanka, southern India, South-East Asia, Hainan Island, and north-eastern Australia (Orousset, 2014). Recently Cai & Huang (2016) described a new genus and species †Cretoleptochromus archaicus (Figs 5A–F, 6A, B) and placed it as incertae sedis within Mastigitae; later Yin et al. (2017) added †Cretoleptochromus burmiticus to this enigmatic genus. Both species are known from Cenomanian amber of Myanmar. Both of them, and especially †C. burmiticus, are remarkably similar to extant species of the morphologically diverse genus Clidicus. †Cretoleptochromus was compared to Clidicus by Cai & Huang (2016) and found to differ from the latter in (cited verbatim) ‘elongate maxillary palpomeres III and IV (not enlarged), elongate pronotum, and slender legs’. Indeed, in some species of Clidicus (e.g. C. bellator, C. rufescens Jałoszyński et al. and others) palpomere 3 is only ∼1.5 times as long as broad, and palpomere 4 is hardly longer than broad (Fig. 6H). However, in many species the palpomeres are elongate nearly as much as those in †Cretoleptochromus, e.g. in Clidicus formicarius (Fig. 6I). The palpomeres in Clidicus and Cretoleptochromus apparently form a morphocline, gradually changing from stout to strongly elongate (Fig. 6A, C–E, G–I). Moreover, within Clidicus, the length of maxillary palps in relation to the head capsule is also highly variable, as demonstrated by examples in Figure 6G–I. Cretoleptochromus represents merely the most elongate variant within the Clidicus morphocline. Its mouthparts (Fig. 6B) do not differ from those of any extant Clidicus (Fig. 6F). An elongate pronotum cannot be used to distinguish †Cretoleptochromus from Clidicus, either. The pronotum in †Cretoleptochromus archaicus (Fig. 5A, B) is only slightly elongate, ∼1.2× as long as broad. The shape and proportions of the pronotum vary considerably among Clidicus, from stout, slightly broader than long (e.g. Clidicus aliquantulus Jałoszyński et al., C. rufescens, C. ganglbaueri Reitter and C. minutus Orousset) to distinctly elongate, 1.2× or slightly more as long as broad (e.g. C. gracilipes Orousset, C. formicarius, C. tonkinensis Lhoste and others). Certainly, slender legs cannot be used to distinguish †Cretoleptochromus from Clidicus, as the length of legs in relation to the body is highly variable and changes gradually in Clidicus species. In extant species of the latter, forms with relatively short (e.g. C. bellator) and extremely long legs (e.g. C. formicarius) can be found. Moreover, legs in Clidicus formicarius (Fig. 1A) are in fact slightly more elongate than those in †Cretoleptochromus archaicus (Fig. 1B). Figure 5. View largeDownload slide Holotype of †Cretoleptochromus archaicus (Cenomanian of Myanmar). A, B, head and prothorax in dorsal view. C, head and prothorax in ventral view. D, head in ventral view. E, F, pterothorax and abdomen in ventral view. Characters and character states (listed in Appendix 3) indicated by arrows. Scale bars: 1 mm. Figure 5. View largeDownload slide Holotype of †Cretoleptochromus archaicus (Cenomanian of Myanmar). A, B, head and prothorax in dorsal view. C, head and prothorax in ventral view. D, head in ventral view. E, F, pterothorax and abdomen in ventral view. Characters and character states (listed in Appendix 3) indicated by arrows. Scale bars: 1 mm. Figure 6. View largeDownload slide Comparison of †Cretoleptochromus (A–E) with extant species of Clidicus (F–I). A, †Cretoleptochromus archaicus, right antenna and maxillary palp in dorsal view. B, †Cretoleptochromus archaicus, mouthparts in ventral view. C–E, †Cretoleptochromus sp. (AMNH Bu-SY17), maxillary palp in anterior, C, D, and dorsal, E, views. F, Clidicus formicarius (Borneo), mouthparts in ventral view. G, Clidicus abbotensis (Australia), head in ventral view. H, Clidicus bellator (Vietnam), head in dorsal view. I, Clidicus formicarius, head in dorsal view. Characters and character states (listed in Appendix 3) indicated by arrows. Abbreviations: bst, basistipes; cd, cardo; lp2–3, labial palpomere 2–3; md, mandible; mst, mediostipes; mxp 1–4, maxillary palpomere 1–4; pd, pedicel; prm, prementum; sc, scape. Scale bars: 0.5 mm. Figure 6. View largeDownload slide Comparison of †Cretoleptochromus (A–E) with extant species of Clidicus (F–I). A, †Cretoleptochromus archaicus, right antenna and maxillary palp in dorsal view. B, †Cretoleptochromus archaicus, mouthparts in ventral view. C–E, †Cretoleptochromus sp. (AMNH Bu-SY17), maxillary palp in anterior, C, D, and dorsal, E, views. F, Clidicus formicarius (Borneo), mouthparts in ventral view. G, Clidicus abbotensis (Australia), head in ventral view. H, Clidicus bellator (Vietnam), head in dorsal view. I, Clidicus formicarius, head in dorsal view. Characters and character states (listed in Appendix 3) indicated by arrows. Abbreviations: bst, basistipes; cd, cardo; lp2–3, labial palpomere 2–3; md, mandible; mst, mediostipes; mxp 1–4, maxillary palpomere 1–4; pd, pedicel; prm, prementum; sc, scape. Scale bars: 0.5 mm. Examination of the holotype of †Cretoleptochromus archaicus revealed a character overlooked by Cai & Huang (2016): a median longitudinal carina of the metaventrite (Fig. 5F). Such a carina was known only in Ablepton and †Rovnoleptochromus. This is an interesting structure, not known in †Cretoleptochromus burmiticus nor any extant species of Clidicus. Such a carina does not occur in an undescribed species identified here as closely resembling †Cretoleptochromus burmiticus, also in Cenomanian Myanmar amber (specimen AMNH Bu-SY17; Supporting Information, Figs S2, S3). Considering the presence and absence of this carina among Cenomanian Cretoleptochromus, it must be regarded as a character variable within this genus, and cannot be used to distinguish †Cretoleptochromus from Clidicus. The length of the maxillary palps in relation to the head, width and relative lengths of maxillary palpomeres (Fig. 6G–I), antennomeres (Fig. 6H, I) and distribution of conspicuously long, erect setae on the head capsule and maxillary palpomeres (Fig. 6G–I) are variable within extant species of Clidicus; also the shape and proportions of the head, pronotum and elytra, and even the shape of the labrum (Orousset, 2014) vary among extant species of this genus, and cannot serve as diagnostic characters to distinguish Cretoleptochromus from Clidicus. Moreover, we report here for the first time a definitive Clidicus species from the Eocene of Russia (Kaliningrad, CCHH 1543-1; Supporting Information, Figs S4, S5), preserved as an inclusion in Baltic amber. This species cannot be formally described due to poor visibility of crucial structures; it is largely covered with air bubbles. However, its general body shape and visible structures of the head, palps, mandibles, antennae, pronotum, elytra and legs are strikingly similar to those of extant middle-sized (5–6 mm) species of Clidicus, e.g. C. crocodylus Jałoszyński. The Eocene specimen has strongly elongate and relatively slender maxillary palps, with palpomere 4 of intermediate length between †Cretoleptochromus archaicus and the slender forms of extant Clidicus. Moreover, maxillary palpomeres of this species bear sparse, conspicuously long, erect setae, known in the Cenomanian †Cretoleptochromus and the slender and large extant species of Clidicus. This specimen supports our hypothesis that Clidicus has evolved in the south-eastern part of Laurasia, where it still occurs today (i.e. in SE Asia), and became widespread within eastern Laurasia, surviving in present-day north-central Europe at least until the Priabonian, presumably until the Eocene–Oligocene climate cooling. Consequently, Clidicus, treated here as a senior synonym of †Cretoleptochromus, is the first Mastigitae genus, whose evolution and distribution are documented from the Cenomanian through the Eocene up through today. †Palaeoleptochromus O’Keefe, 1997 Remarks †Palaeoleptochromus, with its sole species †P. schaufussi from the Campanian of Canada, is the most problematic extinct taxon of Mastigitae. Most characters crucial to place it in a taxonomic context are not observable in the specimen. In our analysis it was placed within the poorly resolved Clidicini sensu nov. (Fig. 3). †Palaeoleptochromus may be a junior synonym of Clidicus, and as the only North American member of this lineage, represents the only firm evidence for a broad distribution of Clidicini during the Upper Cretaceous. However, the fossil has an intriguing character, not known in any remaining Clidicini – a pair of enlarged setae on the posterior margin of the vertex (illustrated in O’Keefe et al., 1997). The placement of †Palaeoleptochromus is still unclear, so we retain this name as valid, pending further study. Papusini Jałoszyński & Brunke trib. nov. urn:lsid:zoobank.org:act:9346A6D8-168A-4FAD-8491-7D7152B6D7BE Type genus: Papusus Casey, 1897, here designated. Diagnosis Papusini differs from all remaining Mastigitae genera by the unique, very large compound eyes located at the middle, or slightly behind the middle, of the head capsule, and a set of synapomorphies known (in different combinations) in other tribes: scape about as long as head, lacking bristles; pedicel not enlarged; maxillary palpomere 3 strongly elongate, with its apical margin nearly perpendicular to the long axis of palpomere, gradually broadening distally; maxillary palpomere 4 subtriangular, broadest at base, much shorter than 3 and distinctly narrower than 3 at apex; vertex and frons lacking median longitudinal groove; posterior margin of vertex lacking a pair of modified setae or large chaetopores; pronotum lacking posterior collar; mesoventral intercoxal process elongate, slender and parallel-sided; posterior margins of mesocoxal cavities carinate; mesocoxa with longitudinal row of several (typically 5) long and thick bristles; admetacoxal margin of metaventrite at each side with indistinct expansion (i.e. not evenly concave but slightly angulate near the mesal third of metacoxa); elytra with longitudinal rows of shallow punctures; aedeagus symmetrical, with slender parameres and straight flagellum. Remarks The placement of Papusus has been problematic for the past 120 years. Casey (1897) placed it in Clidicini, based on a similar form of the maxillary palpomere 4 of Papusus to that of Clidicus. Franz (1985) transferred Papusus to Scydmaenini of Scydmaenitae, but later synonymized it under Leptochromus, automatically moving it back to Clidicini. Papusus was resurrected as a valid name and separate genus by O’Keefe (1998), who carried out a phylogenetic analysis focused on resolving relationships between species of Papusus, but used only Leptochromus as the outgroup. Later, O’Keefe (2002) proposed a sister-group relationship between Papusus and (†Palaeoleptochromus + Leptochromus), but his analysis was restricted to three genera only, with Clidicus as the outgroup. A broader taxon sampling was done by Jałoszyński (2012a, 2016b), who included all genera of Mastigitae known at that time and obtained ambiguous results concerning the placement of Papusus. It was placed, with equal parsimony, as (1) a sister-group to all remaining Clidicini (in a broad, traditional sense) vs. (2) sister to Leptomastacini + all remaining Clidicini (Jałoszyński, 2012a), or as (3) sister to Leptomastacini vs. (4) sister to a clade Clidicus + (remaining Clidicini + Mastigini) (Jałoszyński, 2016b). Consequently, Papusus remained the most problematic of all extant genera and its placement was unclear. Papusus was not placed together with the remaining genera traditionally placed in Clidicini in our phylogenetic reconstructions (neither in parsimony nor in Bayesian analyses), and although its relationships within Mastigitae are still far from being solved, it is clear that Papusus cannot be maintained as a member of Clidicini, based on: the emarginate male sternite 8; the absence of a pronotal collar; uniform setae on frons, vertex and maxillary palpomere 2; narrowly separated antennal cavities; and the presence of a row of mesocoxal bristles. Leptochromini Jałoszyński & Brunke trib. nov. urn:lsid:zoobank.org:act:C45F0203-7DB9-40D2-8B60-6929C30A0FC9 Type genus: Leptochromus Motschulsky, 1855, here designated. Diagnosis Leptochromini differs from all remaining Mastigitae in a unique apomorphy: protrochanteral ventral comb of several (2–7) thick bristles; postgenal bristles are also most likely an autapomorphy of Leptochromini (see Remarks below); and a set of synapomorphies shared with members of other tribes (but in different combinations): scape longer than head, lacking bristles; pedicel unmodified; head capsule strongly transverse; maxillary palpomeres 2 and 3 strongly elongate, palpomere 4 shorter than 3, variable in shape, suboval, subtriangular or nearly rod-like; pronotum with distinct posterior collar; elytra with distinct rows of punctures; mesoventral intercoxal process narrow and elongate, subparallel or slightly narrowing posteriorly; abdominal sternite 8 in males emarginate at middle (this character state remains unstudied in fossils); aedeagus symmetrical or nearly symmetrical, with straight flagellum (also not known in fossils). Remarks Postgenal bristles in our analyses were coded assuming their homology in members of the newly defined tribe Leptochromini and Clidicus formicarius, †Palaeoleptochromus schaufussi, †Cretoleptochromus archaicus and †Cretoleptochromus burmiticus. The previous placement of all these genera (except †Cretoleptochromus treated as incertae sedis) in Clidicini suggested such a homology, with thick postgenal bristles of Leptochromus, †Euroleptochromus and †Rovnoleptochromus presumably developed from sparse and conspicuously long, erect setae present in the same area in some species of the Clidicus/† Cretoleptochromus/†Palaeoleptochromus lineage. However, the topology obtained in our parsimony analysis and reconstruction of ancestral character states falsified this hypothesis, in favour of a parallelism, i.e. an independent evolution of long setae and bristles in Clidicini sensu nov. and Leptochromini. Whether Leptochromini represents the sister-group of †Baltostigini + Mastigini (resolved but unsupported in parsimony analysis) or Clidicini (as found in the Bayesian analysis, but without support, PP = 0.59) remains an unsettled issue. However, the genera placed in Leptochromini form a monophyletic morphological unit in topologies obtained in both analyses, and for this reason they are placed in a separate tribe. Defined as above, Leptochromini differs from Clidicini sensu nov. in the presence of a protrochanteral ventral comb of thick bristles; presence of postgenal bristles (conspicuously thicker than long setae in Clidicini); maxillary palpomere 4 slightly broadening distad, at least in basal half; and abdominal sternite 8 in males emarginate at middle (but not known in fossils). Moreover, the strongly transverse head capsule in Leptochromini (Fig. 1C, D) clearly differs from the subrectangular or subtrapezoidal and weakly transverse head of Clidicini (Fig. 1A, B). †Euroleptochromus Jałoszyński, 2012 †Euroleptochromus setifer Jałoszyński & Brunke sp. nov. (Fig. 7A–J) urn:lsid:zoobank.org:act:9209EBD8-D459-46E8-9108-7BC08F2E55CE Type material Holotype (CCHH 835-3), from Baltic amber (Russia, Kaliningrad); female (confirmed by μCT scan of postabdomen), preserved in a rectangular prism (7 × 6 × 3.5 mm) of amber (CCHH/SDEI). Diagnosis Protrochanter of female subtriangular, with apical bristle and single apical seta as long as trochanter; elytral index <1.7; pronotum strongly elongate, pronotal index nearly 1.3; scape nearly 3.7 times as long as pedicel, each of antennomeres 4–7 at least 1.25× as long as scape. Description Body (Fig. 7A, E–G) slender, length 3.08 mm, dark brown. Head (Fig. 7B, H, I) strongly transverse, length 0.45 mm, width 0.58 mm; occipital constriction (Fig. 7I) about half as wide as width of head, vertex strongly transverse, indistinctly impressed medially and anteriorly confluent with strongly transverse frons; eyes large and strongly projecting from the silhouette of the head; postgenal process (Fig. 7B, E, F, I) nearly 3× as long as broad, with two long and divergent apical bristles. Submentum (Fig. 7I) strongly transverse, demarcated laterally by weakly sinuate and complete hypostomal ridges. Maxillary palp (Fig. 7B, I) much longer than head, palpomere 2 much longer than 3 but shorter than 3 and 4 combined, divided by angulate expansion located in proximal 0.4 into two unequal parts, proximal part distinctly curved, distal part nearly straight and slightly broader, angulate expansion with one robust anterior bristle; palpomere 3 slender, nearly cylindrical in basal half and then gradually broadening distad; palpomere 4 as long as 0.35 of palpomere 3, suboval. Punctures and setae on frons and vertex fine, inconspicuous. Antennae much shorter than body, length 2.26 mm, relative lengths of antennomeres (the shortest antennomere 3 as 1): 4: 1.09: 1.00: 1.45: 1.45: 1.36: 1.36: 1.27: 1.09: 1.09: 1.27. Antennomeres sparsely covered with suberect setae of various lengths. Pronotum (Fig. 7D, E, G) elongate and broadest distinctly in front of middle, length 0.88 mm, width 0.68 mm, pronotal index 1.29; disc convex and sparsely covered with shallow but distinct punctures (those near middle separated by spaces 2–3 times as wide as diameters of punctures), setae indiscernible; posterior collar demarcated by transverse row of four dorsal pits, additionally one laterodorsal pit located at each side of pronotum; posterior pronotal margin with narrow groove. Prosternum (Fig. 7F) with basisternal part about as long as procoxae, lacking discernible traces of notosternal sutures, procoxae contiguous. Mesoventral intercoxal process (Fig. 7J) carinate, parallel-sided, weakly elevated. Metaventrite (Fig. 7F) slightly impressed posteromedially, metacoxae broadly separated. Elytra (Fig. 7E, G) strongly convex, broadest near middle, length 1.75 mm, width 1.08 mm, elytral index 1.63; each elytron with four dorsal and two lateral rows of distinct, large punctures; humeral calli prominent, elongate; elytra sparsely covered with short suberect setae. Legs (Fig. 7A, C, E, F) long and slender, protrochanters (Fig. 7A, C) elongate and subtriangular, each with moderately long apical spine, extremely long, thin apical seta and 3–4 moderately long, thin subapical setae; profemur (Fig. 7C) with four long ventral spines, insertions of the first two spines touching each other, additionally profemur with several long and thin ventral setae; protibiae strongly curved; remaining legs unmodified. Etymology The name setifer (treated here as a noun in apposition) refers to the unusually long seta on each protrochanter. Type locality and horizon Russia, Kaliningrad; Upper Eocene. Remarks Apart from the female trochanter, this species differs from the previously known †E. sabathi in the elytral index 1.63 (1.74 in †E. sabathi), a much more elongate pronotum (pronotal index 1.29 vs. 1.00 in †E. sabathi), the scape 3.67 times as long as pedicel (only 2.94 times in †E. sabathi) and each of antennomeres 4–7 at least 1.25 times as long as scape (0.94–1.06 times in †E. sabathi). In all other characters these two upper Eocene species are very similar. Results of the μCT scan of †E. setifer demonstrated for the first time that strongly curved protibiae in †Euroleptochromus are not male secondary sexual characters, but occur in females (no traces of the aedeagus were found inside the abdomen). This interesting character is, therefore, the same as in the extant and closely related Leptochromus, in which males and females have curved protibiae, and unlike extinct and extant Mastigini, where this character state is restricted to males of some species. Moreover, the μCT technique revealed structures impossible to observe in the inclusion under light microscopy, e.g. the shape of the hypostomal ridges (Fig. 7I) or the intermesocoxal region of the mesoventrite (Fig. 7J). Figure 7. View largeDownload slide Female holotype of †Euroleptochromus setifer sp. nov. (CCHH 835-3; Upper Eocene of Russia); photographs, A–D, and μCT reconstructions, E–J. A, lateroventral habitus. B, head in lateroventral view. C, left foreleg in lateral view. D, pronotum in dorsal view. E, lateral habitus. F, ventral habitus. G, dorsal habitus. H, head in dorsal view. I, head in ventral view. J, intercoxal region of pro- and mesothorax in ventral view. Characters and character states (listed in Appendix 3) indicated by arrows. Scale bars: A, E–G: 1 mm; B–D, H–J: 0.5 mm. Figure 7. View largeDownload slide Female holotype of †Euroleptochromus setifer sp. nov. (CCHH 835-3; Upper Eocene of Russia); photographs, A–D, and μCT reconstructions, E–J. A, lateroventral habitus. B, head in lateroventral view. C, left foreleg in lateral view. D, pronotum in dorsal view. E, lateral habitus. F, ventral habitus. G, dorsal habitus. H, head in dorsal view. I, head in ventral view. J, intercoxal region of pro- and mesothorax in ventral view. Characters and character states (listed in Appendix 3) indicated by arrows. Scale bars: A, E–G: 1 mm; B–D, H–J: 0.5 mm. A very similar specimen (CCHH 835-2, deposited in CCHH/SDEI; Supporting Information, Fig. S6) from the same deposit of Baltic amber (Russian, Kaliningrad) was also studied. It shows some of the diagnostic characters of †E. setifer, i.e. the subtriangular protrochanter with an extremely long apical seta, but it is slightly larger (body length 3.23 mm) and has slightly different proportions of antennomeres, especially the longer scape (4.14× as long as pedicel versus 3.67× in †E. setifer). This inclusion may represent a separate species, but the opaque, milky amber obscuring the body surface, the position of the beetle inside the amber piece and the partly air-exposed surface make it difficult to measure widths of the pronotum and elytra, important for the diagnosis. This specimen does not add any novel characters to the diagnosis of †Euroleptochromus, but demonstrates a considerable variability in the relative length of the scape and pedicel within the genus. All these fossils (i.e. the holotypes of †E. sabathi, †E. setifer and specimen CCHH 835-2), as well as †Rovnoleptochromus, have prominent humeral calli (well-visible in Fig. 7E), typical of winged beetles, but hind wings are not observable in any of them. Their closest living relatives, species of Leptochromus, have similarly large and well-defined humeral calli and are winged, suggesting that Eocene species of Leptochromini were capable of flight. Baltostigini Jałoszyński & Brunke trib. nov. urn:lsid:zoobank.org:act:9C6CEA79-52A6-481D-A042-FF6D8EE53086 Type genus: Baltostigus Jałoszyński, 2016, here designated. Diagnosis Baltostigini differ from all remaining tribes in a unique combination of synapomorphies: maxillary palpomere 3 subtriangular, gradually broadening distally; palpomere 4 axe-shaped, broader than long and broadening distally; both scape and pedicel enlarged and bearing ventral spines; head capsule elongate; vertex evenly convex, not impressed posteromedially and lacking median longitudinal groove; pronotum lacking posterior collar; elytra with rows of punctures at least in anterior half; wings developed; mesoventral intercoxal process carinate and parallel-sided; aedeagus symmetrical, with both parameres equally well-developed. Remarks †Baltostigini, represented only by the Upper Eocene †Baltostigus distributed in north-central Europe, is a group closely related to Mastigini and was previously included in the latter tribe (Jałoszyński, 2016b). Placement of †Baltostigus in a separate tribe is supported by its plesiomorphic characters, not known in any Mastigini (including all extant species and the Cenomanian †Clidicostigus): fully developed wings (Fig. 8A, E) and associated elytral structures (i.e. prominent humeral calli), fully symmetrical aedeagus (Fig. 9C–E), with both parameres well-developed and equally long, and abdominal sternite 8 in males not emarginate. †Baltostigini is an extinct and early diverging group of the ancestral lineage that gave rise to Mastigini. Leptomastacini, Papusini, most Clidicini and Leptochromini have the aedeagi symmetrical or nearly symmetrical (examples are shown in Fig. 9H–P), with two long parameres; the aedeagus in Leptomastacini is twisted in repose (Fig. 9H), similar to that of Mastigini (illustrated by Jałoszyński et al., 2015), that of Clidicini, Papusini and Leptochromini is positioned symmetrically inside the abdomen, with the basal orifice facing dorsad. The symmetrical aedeagus with two long parameres (although in some cases partially fused to the lateral walls of the median lobe) is typical of Scydmaenini, the sister-group of Mastigitae, and can be regarded as the plesiomorphic condition for Mastigitae. †Baltostigini are characterized by this plesiomorphic condition, the aedeagus of †Baltostigus (Fig. 9B–E) is not only symmetrical with two long parameres, but also symmetrically positioned in repose, with its basal orifice facing dorsad. All Mastigini (Fig. 9Q–U), including the Cenomanian †Clidicostigus, have the aedeagus strongly and uniquely transformed, with one paramere much longer than the other; in most ‘advanced’ extant forms one paramere is entirely obliterated and the long one monstrously enlarged (Fig. 9T, U). Based on genital characters and ancestral character state reconstructions, we postulate an early (Cenomanian or earlier) split between †Baltostigus and the ‘asymmetrical’ ancestor of Mastigini (see Discussion). Figure 8. View largeDownload slide Female holotype of †Baltostigus striatipennis sp. nov. (AMNH Bu-SY18; Upper Eocene of Russia); photographs, A–D, line drawings, E–H, and μCT reconstructions, J, K. A, anterodorsal habitus. B, head in laterodorsal and pronotum in dorsal views. C, anterior half of elytra in dorsal view. D, head in anterodorsal view. E, anterodorsal habitus. F, oblique habitus. G, head in anterodorsal view. H, head in laterodorsal and pronotum in dorsal view. J, dorsal habitus. K, pterothorax and abdomen in ventral view. Characters and character states (listed in Appendix 3) indicated by arrows. Scale bars: A, B, D–G, J, K: 1 mm; C, H, I: 0.5 mm. Figure 8. View largeDownload slide Female holotype of †Baltostigus striatipennis sp. nov. (AMNH Bu-SY18; Upper Eocene of Russia); photographs, A–D, line drawings, E–H, and μCT reconstructions, J, K. A, anterodorsal habitus. B, head in laterodorsal and pronotum in dorsal views. C, anterior half of elytra in dorsal view. D, head in anterodorsal view. E, anterodorsal habitus. F, oblique habitus. G, head in anterodorsal view. H, head in laterodorsal and pronotum in dorsal view. J, dorsal habitus. K, pterothorax and abdomen in ventral view. Characters and character states (listed in Appendix 3) indicated by arrows. Scale bars: A, B, D–G, J, K: 1 mm; C, H, I: 0.5 mm. Figure 9. View largeDownload slide Postabdomen of †Baltostigus antennatus (Upper Eocene of Poland) reconstructed by μCT, A–G, and aedeagi of Mastigitae, H–U. A, posterior portion of abdomen and elytra in lateral view. B, terminal abdominal segments and aedeagus in dorsal view. C–E, aedeagus in dorsal, C, ventral, D, and lateral, E, views. F–G, terminal abdominal segments in ventral, F, and dorsal, G, views. H, posterior portion of abdomen of Ablepton treforti (Romania), showing twisted aedeagus in retracted position within. I–U, aedeagus in abparameral view. I, Ablepton treforti. J, Leptomastax stussineri (Bulgaria). K, Taurablepton sp. (Turkey). L, Clidicus aliquantulus (Vietnam). M, Clidicus gracilipes Orousset (Sumatra). N, Leptochromus agilis (Costa Rica). O, Leptochromus laselva (Costa Rica) showing extruded flagellum. P, Papusus macer (USA). Q, Mastigus spinicornis (RSA). R, apical portion, †Clidicostigus arachnipes (Cenomanian of Myanmar), reconstructed by μCT (after Jałoszyński et al. 2017a). S, Palaeostigus tenuis (Leleup) (RSA). T, aedeagus of Stenomastigus vulgaris (Lhoste) (RSA). U, Stenomastigus longicornis Boheman (RSA). Characters and character states (listed in Appendix 3) indicated by arrows. Abbreviations: aed, aedeagus; apo9, apodeme of tergite 9; bc, basal capsule; bo, basal orifice; cp, copulatory piece; el, elytron; end, permanently extruded endophallus; fl, flagellum; ht9, hemitergite 9; ml, median lobe; pm, paramere; st8, sternite 8; st9, sternite 9; t10, tergite 10. Scale bars: 0.25 mm; Figures H–U not to the same scale. Figure 9. View largeDownload slide Postabdomen of †Baltostigus antennatus (Upper Eocene of Poland) reconstructed by μCT, A–G, and aedeagi of Mastigitae, H–U. A, posterior portion of abdomen and elytra in lateral view. B, terminal abdominal segments and aedeagus in dorsal view. C–E, aedeagus in dorsal, C, ventral, D, and lateral, E, views. F–G, terminal abdominal segments in ventral, F, and dorsal, G, views. H, posterior portion of abdomen of Ablepton treforti (Romania), showing twisted aedeagus in retracted position within. I–U, aedeagus in abparameral view. I, Ablepton treforti. J, Leptomastax stussineri (Bulgaria). K, Taurablepton sp. (Turkey). L, Clidicus aliquantulus (Vietnam). M, Clidicus gracilipes Orousset (Sumatra). N, Leptochromus agilis (Costa Rica). O, Leptochromus laselva (Costa Rica) showing extruded flagellum. P, Papusus macer (USA). Q, Mastigus spinicornis (RSA). R, apical portion, †Clidicostigus arachnipes (Cenomanian of Myanmar), reconstructed by μCT (after Jałoszyński et al. 2017a). S, Palaeostigus tenuis (Leleup) (RSA). T, aedeagus of Stenomastigus vulgaris (Lhoste) (RSA). U, Stenomastigus longicornis Boheman (RSA). Characters and character states (listed in Appendix 3) indicated by arrows. Abbreviations: aed, aedeagus; apo9, apodeme of tergite 9; bc, basal capsule; bo, basal orifice; cp, copulatory piece; el, elytron; end, permanently extruded endophallus; fl, flagellum; ht9, hemitergite 9; ml, median lobe; pm, paramere; st8, sternite 8; st9, sternite 9; t10, tergite 10. Scale bars: 0.25 mm; Figures H–U not to the same scale. †Baltostigus preserved another character state that is ancestral for the clade †Baltostigus + Mastigini, i.e. the deep elytral punctures arranged in longitudinal rows (best visible in the new species described below, and only partly developed in two previously described species; see Fig. 1F). Among Mastigini, this character state can be found only in the ancient, extinct Cenomanian †Clidicostigus (Fig. 1E), whereas the genera that survived until the present day (i.e. Mastigus, Palaeostigus and Stenomastigus) have only weakly marked, fine and often indistinct vestigial elytral rows or striae. †Baltostigus Jałoszyński, 2016 †Baltostigus striatipennis Jałoszyński, Brunke & Yamamoto sp. nov. (Figs 8A–K; Supporting Information, Figs S7, S8) urn:lsid:zoobank.org:act:72B35B19-F014-4BF9-B29C-8B7728B7ED56 Type material Holotype (AMNH Bu-SY18), from Baltic amber (Russia, Kaliningrad); female (confirmed by μCT scan of postabdomen), preserved in a slightly irregular prism (14 × 12 × 5 mm) of amber (AMNH). Diagnosis Each elytron with ten rows of small punctures located in sharply marked narrow grooves forming elytral striae; pronotum 1.3× as long as broad; scape only 4.33× as long as antennomere 3, and antennomeres 3, 9 and 10 equal in length. Description Body (Fig. 8A, E, J) relatively stout, brown, length 3.33 mm. Head (Fig. 8B, D, F, G) elongate, length 0.55 mm, width 0.50 mm; occipital constriction broader than half width of head, vertex transverse and evenly convex; frons subtrapezoidal, between antennal insertions forming subtriangular projection with shallow impression behind its middle; eyes large and strongly projecting from the silhouette of the head. Maxillary palp (Fig. 8H) slightly longer than head, palpomere 2 slender and in proximal half nearly cylindrical, then gradually broadening to apex; palpomeres 3 and 4 combined shorter than 2; palpomere 3 elongate, gradually and strongly broadening from base to apex; palpomere 4 strongly broadening from base to apex, with rounded apical margin. Punctures on frons and vertex fine, inconspicuous; setae short, moderately dense, suberect. Antennae (Fig. 8G–I) much shorter than body, length 2.46 mm, relative lengths of antennomeres (the shortest antennomere 3 as 1): 4.33: 2.17: 1.00: 1.17: 1.25: 1.17: 1.17: 1.08: 1.00: 1.00: 1.08. Scape with five or six pairs of long, ventral spines; pedicel with four pairs of similar spines; basic vestiture of all antennomeres short, moderately dense and recumbent, all antennomeres with at least several long and suberect setae. Pronotum (Fig. 8B, H) elongate and broadest near anterior third, length 0.78 mm, width 0.60 mm, pronotal index 1.29; disc convex, with indistinct transverse basal impression and covered with distinct, unevenly distributed punctures separated by spaces 0.5–2 times as wide as their diameters, setae short, sparse, suberect. Mesoventral intercoxal process (Fig. 8K) carinate, slender, parallel-sided, weakly elevated, mesoventrite in front of mesocoxal cavities evenly convex. Metaventrite (Fig. 8K) subtrapezoidal, broadening posteriorly, metacoxae broadly separated. Elytra (Fig. 8C, E, J) strikingly broader than pronotum, strongly convex, broadest slightly behind middle, length 2.00 mm, width 1.40 mm, elytral index 1.43; each elytron with ten narrow and deeply impressed striae with small and shallow punctures, six striae are visible in dorsal view, striae 1 and 3 (counting from elytral suture) connected posteriorly; adsutural region distinctly raised in posterior half of elytra; humeral calli prominent and short; elytra sparsely covered with short suberect setae forming single or double slightly irregular rows between striae. Legs (Fig. 8A, E, F) long and slender, unmodified. Hind wings present, right wing protruding from under elytra (Figs 8A; Supporting Information, Fig. S7). Etymology The name striatipennis is an adjective that refers to the fully striate elytra. Type locality and horizon Russia, Kaliningrad; Upper Eocene. Remarks This species clearly differs from previously described †B. antennatus and †B. horribilis in the fully developed elytral striae, while in the two previously described species the striae are incomplete and marked only near the elytral base. †Baltostigus striatipennis also has clearly different proportions of the antennomeres, with scape 4.33× as long as antennomere 3 (7.0–7.2× in †B. antennatus and †B. horribilis), and antennomeres 3, 9 and 10 equal in length (antennomeres 9 and 10 1.29–1.6× as long as 3 in †B. antennatus and †B. horribilis). A narrow adsutural region distinctly elevated in the posterior third of the elytra in the female of †B. striatipennis resembles a similar modification in females of some extant species of Mastigini, especially in Stenomastigus. Males of such species are always much more slender and their elytra are evenly convex. However, in Stenomastigus the female elytra have impressions near their anterior fourth to receive the trochanters of males during copulation, which is an adaptation to stabilize the mating position (Jałoszyński et al., 2015). Such a structure was not present in females of †Baltostigus, and therefore mating strategies might have differed from those in Mastigini, their sister-clade. Mastigini Fleming, 1821 sensu nov. Type genus: Mastigus Latreille, 1802. Diagnosis Mastigini are restricted here to genera sharing: an enlarged and ventrally spiny scape and pedicel; elongate head with median longitudinal groove on posteriorly impressed vertex; narrowly separated antennal insertions; pronotum lacking posterior collar; and aedeagus asymmetrical, with one paramere distinctly shorter than the other one (in some cases only one paramere is visible, the other one is either vestigial or completely obliterated). †Clidicostigus Jałoszyński, Brunke & Bai, 2017 = Cascomastigus Yin & Cai, 2017 syn. nov. Remarks †Cascomastigus does not differ in any characters from †Clidicostigus; their diagnostic features, including uniquely shaped maxillary palps with an asymmetrical palpomere 4, and elytral striae, are identical. Neither structural nor spatiotemporal arguments support a separate placement of these taxa, and †Cascomastigus is here placed as a junior synonym of †Clidicostigus (the former name with the online publication date 2017.03.07; the latter 2017.01.03). DISCUSSION After recent discoveries of Cretaceous and Eocene fossils, Mastigitae became a Scydmaeninae supertribe with over 40% of genera known only from amber inclusions. Although morphologically well-studied and unambiguously documented since the Cenomanian, Mastigitae remained a group with surprisingly problematic phylogenetic relationships among its components. Clidicini, Leptomastacini and Mastigini in the traditional sense were established solely on the basis of extant genera. The monophyly of Clidicini was already questioned (Jałoszyński, 2012a, 2016b), and problems of Cai & Huang (2016) to place their †Cretoleptochromus in this tribe reflect unclear diagnoses and non-monophyly of Clidicini in the traditional sense that we aimed to improve here. As each new extinct genus was discovered, these additional character states considerably modified previous hypotheses of homology, topology and biogeography (O’Keefe, 2002; Jałoszyński, 2012a, 2016b, and present results), and it became clear that characters of the extant genera of Mastigitae are insufficient to reconstruct the evolutionary relationships among them. Our results based on a wider taxon sampling supported these suspicions. At this current stage of knowledge, we combined all available data to shed light on the evolution of this enigmatic group of ant-like stone beetles, and with new character states of extinct taxa included in phylogenetic reconstructions, we demonstrate that the present-day diversity of Mastigitae is relictual and extinctions played an important role in the observed disjunctive distribution of extant taxa. Reclassification of Mastigitae Based on the phylogenetic hypothesis shown in Figure 3, a reclassification of Mastigitae was unavoidable. The tribe Clidicini in its traditional sense (i.e. comprising Clidicus, Leptochromus, †Palaeoleptochromus, †Euroleptochromus, †Rovnoleptochromus and Papusus) was not resolved as a monophyletic unit. This explains previous problems to define Clidicini. In one of the most recent attempts, O’Keefe (2002) listed an elongated maxillary palpomere 3 (vs. subtriangular or only as long as wide at apex in the remaining Mastigitae); elongate, dorsoventrally curved aedeagus with large parameres and ‘reduced’ cylindrical median lobe (vs. elongate and somewhat dorsoventrally curved but ‘otherwise different’ in Leptomastacini, and highly asymmetrical in Mastigini); and labial palpomere 3 elongate and slender (vs. short) as synapomorphies to distinguish Clidicini from all remaining Mastigitae. However, an elongate maxillary palpomere 3 of a very similar shape can be found in Mastigini; the differences in aedeagal structures were explained in a very unclear way and in fact the aedeagi of Leptomastacini and Clidicini sensu O’Keefe differ merely in the shape of parameral apices; and the labial palpomere 3 is strongly elongate and slender in all Mastigitae (somewhat reduced in relation to palpomere 2 only in Mastigini). The new division of this problematic group of genera into Clidicini sensu nov., Papusini trib. nov. and Leptochromini trib. nov. improves the classification by naming monophyletic units as tribes and providing diagnostic characters to identify them. We also propose to separate extinct †Baltostigus from Mastigini, on the basis of clearly defined and numerous morphological differences in the maxillary palps, vertex, elytra and wings, mesoventral process and the aedeagus, and a presumed ancient, late Cretaceous or earlier divergence between these groups, despite the only moderately strong support for its monophyly in our analysis. Historical biogeography Recent discoveries of the first Cenomanian Clidicini sensu nov. (Cai & Huang, 2016; Yin et al., 2017a) and Mastigini sensu nov. (Jałoszyński et al., 2017a; Yin et al., 2017b) demonstrated the origins of all newly defined tribes (Fig. 3) to be at minimum ~99 Mya. Based on results of all reconstructions and the spatiotemporal distribution of known fossils and extant taxa, the hypothesis assuming the Northern Hemisphere origins of Mastigitae seems well corroborated by two of the three analyses reported. Analysis 3 of Supporting Information, Appendix S2 differs significantly in this regard but it also gave the most ambiguous results. Analysis 3 indicated Australia as a part of the ancestral Mastigitae distribution, which seems highly unlikely because only a single species occurs in Australia, and it seems to be derived within the Asian clade. It remains unclear, however, whether the ancestor of Mastigitae evolved in the North American or Eurasian part of Laurasia. Both alternate scenarios require several dispersal events to explain the current distribution of Mastigitae. The oldest fossils, however, come from the Cenomanian of Myanmar, and the only Cretaceous North American species of Clidicini is ∼19 Myr younger, which may indicate the Eurasian part of Laurasia, or more precisely its south-eastern portion, as the ancestral area for Mastigitae. In this scenario, the divergence between Leptomastacini and the remaining Mastigitae must have taken place before the earliest Cenomanian in the Eurasian part of Laurasia, possibly in its southern portion, followed by a dispersal of Leptomastacini into the present-day Mediterranean basin. Clidicini have been evolving in situ, in south-eastern Laurasia, and dispersed to the west (i.e. to its North American part) during the Campanian or earlier, where Nearctic †Palaeoleptochromus and the entire Clidicini lineage has since gone extinct. Clidicini has also dispersed from SE Asia into northern Australia via Sundaland, presumably recently, during the Pleistocene low sea-level periods (e.g. Metcalfe et al., 2001; Bruyn et al., 2014) and into the Indian subcontinent, no earlier than the Paleogene when it collided with the Eurasian Plate (e.g. Aitchison et al., 2007). The morphological similarity of western Laurasian Campanian †Palaeoleptochromus and south-eastern Laurasian Cenomanian Clidicus (= Cretoleptochromus), and the location of the present-day biodiversity center of Clidicus in SE Asia support this scenario of Clidicini evolution and dispersal. Papusus, treated here as the sole member of Papusini, is morphologically different from all remaining Mastigitae and may represent an offshoot of the eastern Laurasian Mastigitae lineage that has dispersed into the western (North American) part of the Laurasian supercontinent, and diverged no later than the Cenomanian when members of part of its sister lineage (Mastigini) were already present. The dispersal of Papusini, however, might have occurred later; there is no fossil evidence to address this issue. Leptochromini are currently distributed in Central and South America, but fossils unambiguously placed in this tribe are known from the Eocene of Europe. Moreover, †Leptochromus palaeomexicanus was found in Oligocene/Miocene (22–26 Mya) Chiapas Mexican amber. The ancestral Leptochromini lineage, according to the scenario proposed here, has evolved within the Eurasian part of Laurasia and split twice: into the †Rovnoleptochromus lineage and †Euroleptochromus + Leptochromus. The former survived in the area of present-day Ukraine at least until the Priabonian. Later, the Leptochromus + †Euroleptochromus lineage split and Leptochromus dispersed into North America, from where it dispersed further southwards to colonize northern South America. The Leptochromus lineage has successfully survived until today, although it is poor in species and morphologically very uniform, while the European †Rovnoleptochromus and †Euroleptochromus lineages have gone extinct, presumably as a result of the Eocene–Oligocene climate cooling (e.g. Liu et al., 2009). According to our results, the ancestral lineage of Mastigitae that gave rise to †Baltostigini and Mastigini also evolved in the Eurasian part of Laurasia, and its divergence into two tribes may be quite ancient, no later than the Cenomanian, as Mastigini (i.e. †Clidicostigus) is known from Myanmar amber. Mastigini and †Baltostigini were widespread within eastern Laurasia, where the northern †Baltostigini clade had gone extinct (presumably during the Eocene–Oligocene climate cooling), and the southern (currently Mediterranean) Mastigini has survived and relatively recently dispersed into South Africa. The hypothesis of recent divergence of European and South African species of Mastigini, as a result of dispersal followed by habitat fragmentation and formation of barriers, is strongly supported by the striking morphological similarity of these species, so much so that thus far Mastigus, Palaeostigus and Stenomastigus were placed in a polytomy in all attempts to resolve their relationships (Jałoszyński, 2012a, 2016b and the present study), and Palaeostigus occurs in both parts of this disjunctive range. Evolution of morphological structures The ancient differentiation of all newly defined Mastigitae tribes, disjunctions generated by extinctions of Cretaceous and Eocene taxa, and adaptations of modern taxa to live in strikingly different habitats (forest leaf litter, soil, under stones in arid deserts) probably explain the observed morphological distinctiveness of the five extant lineages (i.e. Australo-Oriental Clidicini; Neotropical Leptochromini; Mediterranean Leptomastacini; Mediterranean and South African Mastigini). The ancestor of Mastigitae, as inferred from reconstructions of ancestral character states (Supporting Information, Appendix S1), might have been similar to the extant Scydmaenini (the sister-group of Mastigitae). It was presumably a beetle smaller than any Cretaceous, Eocene or extant Clidicini and Mastigini, closer in body size to Leptomastacini, Papusini or Leptochromini (i.e. not exceeding 4 mm, but possibly smaller), lacking any conspicuous modifications of the antennae (except the scape at least as long as the head), maxillary palps and legs, with large eyes, pronotum lacking posterior collar, elytral base lacking foveae and the aedeagus resembling that of the extant Adrastia Broun or Pseudoeudesis Binaghi, i.e. symmetrical, with free, slender parameres and a simple, un-looped flagellum. The ancestor of Mastigitae clearly differed from Scydmaenini by the broadly separated antennal insertions and conspicuous rows of large and deep punctures on each elytron. In addition to forms strikingly similar to extant Mastigitae, the Upper Cretaceous of south-eastern Eurasia was inhabited by taxa with body modifications even more extreme than those of extant species. Among the extant taxa, Mastigini such as Stenomastigus have the most elongated body form, with extremely long legs and antennae, adaptations for life on the surface of the ground and plants, and for running quickly after prey (Jałoszyński, 2012b, 2016a). The hallmark of Mastigini, the enlarged and spiny scape and pedicel, is especially well-developed in Stenomastigus (e.g. Jałoszyński, 2012b). While distinctive, it does not function as a ‘springtail trap’ as initially hypothesized by Jałoszyński (2012a) and further discussed by Yin et al. (2017b) (Jałoszyński, unpublished observations). However, in the Upper Cretaceous †Clidicostigus (Fig. 1E) the body was even more slender, the legs almost monstrously elongate, and the scape and pedicel more enlarged than in Stenomastigus. It seems that a considerable morphological diversity of Mastigitae had evolved and differentiated already before the Cenomanian, and extreme morphotypes like †Clidicostigus have gone extinct. A similar case of an extinct extreme form was discovered recently among the glandulariine scydmaenines. The Turonian (∼90 Mya) †Hyperstenichnus Jałoszyński et al., morphologically similar to the extant mite-feeding Stenichnus Thomson, had strikingly much larger labial suckers to immobilize its apparently mite prey than any of its extant relatives (Jałoszyński et al., 2017b). These extreme morphological adaptations in Scydmaeninae have apparently been eliminated by evolution, as presumably less extreme forms were favoured by unknown factors of selective pressure. From a morphological and evolutionary standpoint, the recent discovery of Cenomanian †Clidicostigus and Eocene †Baltostigus have been most important for understanding the evolution of Mastigitae. The ancient †Clidicostigus looked similar to the extant Mastigini (especially Stenomastigus); it had an asymmetrical aedeagus and was presumably wingless (judging from the lack of humeral calli), consistent with its closest living relatives. The apex of the aedeagus of †Clidicostigus arachnipes, reconstructed by μCT in Jałoszyński et al. (2017a), is very similar to that of the extant South African Mastigus spinicornis, the type species of Mastigus (Fig. 9R vs. 9Q). Moreover, the copulatory piece in †Clidicostigus arachnipes was developed in a way similar to that of other Mastigini, suggesting a permanently everted and membranous endophallus (not preserved or impossible to visualize with μCT), and a presumably looped flagellum that cannot be extruded from the aedeagus during copulation (Jałoszyński et al., 2015). The much younger †Baltostigus (Figs 2F, 8) had a body conspicuously smaller and stouter than that of any Mastigini, fully developed wings and a symmetrical aedeagus (Fig. 9C–E), which was additionally symmetrically positioned inside the abdomen in repose (Fig. 9B), with its basal orifice facing up. Its aedeagus was similar to the copulatory organs of Leptomastacini (Fig. 9H–K), Clidicini sensu nov. (Fig. 9L–O) and Papusini (Fig. 9P), and its shape is indicative of a simple, non-looped flagellum that can be extruded during copulation (as that in Fig. 9O). Before the discovery of †Clidicostigus, the clearly plesiomorphic symmetrical aedeagal structure, elytral rows of punctures and the winged condition of †Baltostigus might have been interpreted as representing an ancestral lineage of extant Mastigini, and consequently the development of a larger and more slender body, reduction of elytral striae to barely discernible rudiments, loss of wings and, most importantly, the asymmetrization of male genitalia, could be presumed to have taken place relatively recently, after the Eocene (Jałoszyński, 2016b). †Clidicostigus with its deep elytral striae, lack of wings and an asymmetrical aedeagus falsified this hypothesis and demonstrated that the split between Mastigini sensu nov. and †Baltostigini had occurred much earlier, during or before the Cenomanian, and that during the Eocene both lineages co-existed in Eurasia. The ancestral character reconstructions and phylogenies obtained in our study support the hypothesis of a winged ancestor of Mastigini + †Baltostigini, with striate elytra and a symmetrical aedeagus. The latter is of great interest, as the asymmetrization of male genitalia is surprisingly ancient (having occurred 99 Mya or earlier), and triggered the development of the most unusual and unique copulation in the beetles, which is found in the extant South African Stenomastigus. The increasing asymmetrization of parameres in combination with an immovable flagellum and permanently everted membranous, inflatable endophallus led to copulation with the long paramere inserted into the subelytral space and stabilized with additional female elytral modifications (Jałoszyński et al., 2015). Copulation with a symmetrical aedeagus persisted in this lineage via †Baltostigini until at least the Eocene. Similar to the asymmetrization of male genitalia, the loss of flight in Mastigini must have occurred no later than ~99 Mya, possibly when forms similar to †Clidicostigus developed extremely long and slender legs for efficient hunting (like their living Mediterranean and South African relatives), and started to rely on running, instead of flying, as a dispersal method. The flightless condition was presumably ancestral for Mastigini, whereas the ancestor of Mastigini + winged †Baltostigini was capable of flight. The loss of wings must have independently taken place in the ancestor of Leptomastacini, a group that today includes exclusively wingless species. A third loss of wings has occurred within Clidicini sensu nov., as some extant species of Clidicus are wingless (e.g. C. bellator and C. crocodylus) and some have wings (e.g. C. abbotensis); the Cenomanian †C. burmiticus had apparently preserved the ancestral state with complete wings (Yin et al., 2017a). The fourth independent loss of wings occurred in the ancestor of Papusini, a group that today is wingless. Four independent losses of wings seem more plausible than an alternative scenario that assumes a single loss of wings in the ancestor of Mastigitae and three (in Clidicini, Leptochromini and †Baltostigini) reversals. However, multiple reversals are known among insects (e.g. Whiting et al., 2003), and such a scenario, or a mixed scenario of wing losses, reversals and repeated losses, cannot be ruled out. CONCLUSIONS Based on results of phylogenetic analyses comprising a wide extant and extinct taxon sampling, we reclassify Mastigitae into six monophyletic units: Leptomastacini, Clidicini, Papusini, Leptochromini, †Baltostigini and Mastigini. We postulate that Mastigitae have undergone a substantial morphological differentiation during or (more likely) before the Cenomanian, when members of Clidicini and Mastigini already inhabited south-eastern Laurasia and exhibited some highly derived character states; dispersals and extinctions are responsible for the current and highly disjunct distribution of this supertribe. Eurasia was inferred as the ancestral distribution area for Mastigitae, and an ancestor similar to the extant Scydmaenini, but with broadly separated antennal insertions and deep elytral striae was reconstructed. We demonstrate that the first step in the evolution of a highly asymmetrical aedeagus and extremely complex copulation in Stenomastigus occurred at least 99 Mya. Moreover, we infer four independent wing losses during the evolution of Mastigitae. As the first divergence in Mastigitae took place during or before the Late Cretaceous, presumably within south-eastern Laurasia, further study of Myanmar amber could be expected to yield members of Leptomastacini, a tribe still unknown in the fossil record. SUPPORTING INFORMATION Additional Supporting Information may be found in the online version of this article at the publisher’s web-site: Appendix S1. Reconstructed ancestral character states for Mastigitae. Appendix S2. Reconstruction of ancestral areas of distribution. Figure S1. Consensus (50% majority rule) tree obtained in Bayesian analysis; posterior probability values higher than 0.5 given at nodes. Figure S2. Clidicus (=Cretoleptochromus) sp. (AMNH Bu-SY17; Cenomanian of Myanmar). A, Dorsal habitus. B, elytra showing setation. C, elytra under different lighting, showing rows of punctures. D, ventral habitus. E, metaventrite and abdomen in ventral view. F, G, head in anterodorsal and slightly lateral view. H, head in anterolateral and slightly dorsal view. Scale bars: A–E: 2 mm; F–H: 0.5 mm. Figure S3. Clidicus (= Cretoleptochromus) sp. (AMNH Bu-SY17; Cenomanian of Myanmar). A, dorsal habitus (cf. S2 A). B, ventral habitus (cf. S2 D). C, head in anterodorsal and slightly lateral view (cf. S2 F–G). D, head in anterolateral and slightly dorsal view (cf. S2 H). Scale bars: A, B: 2 mm; C, D: 0.5 mm. Figure S4. Clidicus sp. (CCHH 1543-1; Upper Eocene of Russia). A, dorsal habitus. B, ventral habitus. C, head in dorsolateral view. D, head in ventrolateral view. Scale bars: A, B: 2 mm; C, D: 1 mm. Figure S5. Clidicus sp. (CCHH 1543-1; Upper Eocene of Russia). A, dorsal habitus (cf. S4 A). B, ventral habitus (cf. S4 B). C, head in dorsolateral view (cf. S4 C). D, head in ventrolateral view (cf. S4 D). Scale bars: A, B: 2 mm; C, D: 1 mm. Figure S6. Euroleptochromus sp. (CCHH 835-2; Upper Eocene of Russia). A, right lateral habitus. B, left laterodorsal habitus. C, head, prothorax and fore leg in lateral view. D, ventral habitus. Scale bars: 1mm. Figure S7. Female holotype of †Baltostigus striatipennis Jałoszyński, Brunke & Yamamoto sp. nov. (AMNH Bu-SY18; Upper Eocene of Russia). Scale bar: 1mm. Figure S8. Female holotype of †Baltostigus striatipennis Jałoszyński, Brunke & Yamamoto sp. nov. (AMNH Bu-SY18; Upper Eocene of Russia), detail of Fig. S7. Scale bar: 1mm. ACKNOWLEDGEMENTS We thank museum curators and collectors who made specimens available to us (including holotypes): Ming Bai (TGEM), Chengyang Cai (NIGP), Giulio Cuccodoro (MHNG), Christel and Hans Werner Hoffeins (CCHH), Ivan Löbl (MHNG), Heinrich Meybohm (cHM), Marc De Meyer (RMCA), Ruth Müller (TMSA), Evgeny Perkovsky (SIZK) and Harald Schillhammer (NHMW). MicroCT imaging of amber inclusions was performed by Brian Metscher (University of Vienna) with support from the EU project BIG4 ITN (see below). We also thank Viola Winkler (Metscher Lab, University of Vienna) for assistance with μCT reconstructions and scanning. Anna Siudzińska (Laboratory of Electron Microscopy, Wrocław Research Centre EIT+) is acknowledged for taking SEM micrographs. This project has received funding in the form of fellowships to AJB from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 642241 (BIG4) (Vienna, Austria), and the NSERC PRP program (Ottawa, Canada). [Version of Record, published online 19 April 2018; http://zoobank.org/urn:lsid:zoobank.org:pub:32E47418-1241-4DAB-BB92-9E2139CB3006] APPENDIX 1 Study methods are as follows: perm., disarticulated specimen in permanent slide preparations; LM, light microscopy; μCT, microcomputer tomography; SEM, gold-coated disarticulated specimen examined by a scanning electron microscopy; temp., intact specimen in temporary slide preparation; if characters were extracted from literature and the type material has not been examined, an appropriate citation is given instead of the study method and depository; HT and PT stand for holotype and paratype, respectively. Terminal taxa (alphabetically) and data of specimens used in the phylogenetic analysis Terminal taxon Country of origin Sex Study method Depository* Euaesthetinae Euaesthetus ruficapillus (Lacordaire, 1835) Poland ♂, ♀ SEM, LM/perm. cPJ Scydmaeninae: Scydmaenini Adrastia edwardsi (Sharp, 1874) New Zealand ♂ LM/temp. NHMW Pseudoeudesis sulcipennis (Reitter, 1890) Tunisia ♂, ♀ LM/temp. MNHW Scydmaenus tarsatus Müller & Kunze, 1822 Poland ♂, ♀ SEM, LM/perm. cPJ Scydmaeninae: Mastigitae Ablepton trefortiFrivaldszky, 1877 Romania ♂, ♀ SEM, LM/perm. cPJ †Baltostigus antennatus Jałoszyński, 2016 Eocene of Poland ♂ μCT, LM CCHH/SDEI †Baltostigus horribilis Jałoszyński, 2016 Eocene of Lithuania ? LM FMNH †Baltostigus striatipennis sp. nov. (AMNH Bu-SY18) Eocene of Russia ♀ μCT, LM AMNH †Cascomastigus monstrabilis Yin & Cai, 2017 Cenomanian of Myanmar HT ♂, PT ♀ Yin et al., 2017 †Clidicostigus arachnipes Jałoszyński et al., 2017 Cenomanian of Myanmar HT ♂ μCT, LM TGEM Clidicus bellator Jałoszyński et al., 2003 Vietnam PT ♂, PT ♀ SEM, LM/perm. cPJ Clidicus formicarius Pascoe, 1866 Borneo ♂, ♀ SEM, LM cPJ †Cretoleptochromus archaicus Cai & Huang, 2016 Cenomanian of Myanmar HT? LM NIGP †Cretoleptochromus burmiticus Yin et al., 2017 Cenomanian of Myanmar HT ♂, PT ♂, PT ♀ Yin et al., 2017 †Cretoleptochromus sp. (AMNH Bu-SY17) Cenomanian of Myanmar ♂ LM AMNH †Euroleptochromus sabathi Jałoszyński, 2012 Eocene of Lithuania HT ♀ LM FMNH †Euroleptochromus setifer sp. nov. (CCHH 835-3) Eocene of Russia HT ♀, PT ♀ μCT, LM CCHH/SDEI Leptochromus agilis (Sharp, 1887) Costa Rica ♂, ♀ LM/temp. MHNG Leptochromus laselva Lord et al., 2014 Costa Rica PT ♂, PT ♀ SEM, LM/temp. cPJ Leptomastax stussineri Reitter, 1880 Bulgaria ♂, ♀ SEM, LM/perm. cPJ Mastigus spinicornis (Fabricius, 1787) RSA ♂, ♀ LM/temp. RMCA †Palaeoleptochromus schaufussi O’Keefe, 1997 Campanian of Canada ♀ O’Keefe et al., 1997 Palaeostigus bifoveolatus (Boheman, 1851) RSA ♂, ♀ SEM, LM/perm. cPJ Palaeostigus ruficornis schimitscheki (Machulka, 1944) Turkey ♂, ♀ SEM, LM/perm. cPJ Papusus macer Casey, 1897 USA ♂, ♀ SEM, LM/temp. cPJ †Rovnoleptochromus ableptonoides Jałoszyński & Perkovsky, 2016 Eocene of Ukraine ? LM SIZK Stenomastigus varii Leleup, 1968 RSA ♂, ♀ SEM, LM/perm. TMSA Taurablepton asitawandas Besuchet, 1969 Turkey ♀ LM/temp. MHNG Taurablepton sp. Turkey ♂ SEM, LM/temp. cHM Terminal taxon Country of origin Sex Study method Depository* Euaesthetinae Euaesthetus ruficapillus (Lacordaire, 1835) Poland ♂, ♀ SEM, LM/perm. cPJ Scydmaeninae: Scydmaenini Adrastia edwardsi (Sharp, 1874) New Zealand ♂ LM/temp. NHMW Pseudoeudesis sulcipennis (Reitter, 1890) Tunisia ♂, ♀ LM/temp. MNHW Scydmaenus tarsatus Müller & Kunze, 1822 Poland ♂, ♀ SEM, LM/perm. cPJ Scydmaeninae: Mastigitae Ablepton trefortiFrivaldszky, 1877 Romania ♂, ♀ SEM, LM/perm. cPJ †Baltostigus antennatus Jałoszyński, 2016 Eocene of Poland ♂ μCT, LM CCHH/SDEI †Baltostigus horribilis Jałoszyński, 2016 Eocene of Lithuania ? LM FMNH †Baltostigus striatipennis sp. nov. (AMNH Bu-SY18) Eocene of Russia ♀ μCT, LM AMNH †Cascomastigus monstrabilis Yin & Cai, 2017 Cenomanian of Myanmar HT ♂, PT ♀ Yin et al., 2017 †Clidicostigus arachnipes Jałoszyński et al., 2017 Cenomanian of Myanmar HT ♂ μCT, LM TGEM Clidicus bellator Jałoszyński et al., 2003 Vietnam PT ♂, PT ♀ SEM, LM/perm. cPJ Clidicus formicarius Pascoe, 1866 Borneo ♂, ♀ SEM, LM cPJ †Cretoleptochromus archaicus Cai & Huang, 2016 Cenomanian of Myanmar HT? LM NIGP †Cretoleptochromus burmiticus Yin et al., 2017 Cenomanian of Myanmar HT ♂, PT ♂, PT ♀ Yin et al., 2017 †Cretoleptochromus sp. (AMNH Bu-SY17) Cenomanian of Myanmar ♂ LM AMNH †Euroleptochromus sabathi Jałoszyński, 2012 Eocene of Lithuania HT ♀ LM FMNH †Euroleptochromus setifer sp. nov. (CCHH 835-3) Eocene of Russia HT ♀, PT ♀ μCT, LM CCHH/SDEI Leptochromus agilis (Sharp, 1887) Costa Rica ♂, ♀ LM/temp. MHNG Leptochromus laselva Lord et al., 2014 Costa Rica PT ♂, PT ♀ SEM, LM/temp. cPJ Leptomastax stussineri Reitter, 1880 Bulgaria ♂, ♀ SEM, LM/perm. cPJ Mastigus spinicornis (Fabricius, 1787) RSA ♂, ♀ LM/temp. RMCA †Palaeoleptochromus schaufussi O’Keefe, 1997 Campanian of Canada ♀ O’Keefe et al., 1997 Palaeostigus bifoveolatus (Boheman, 1851) RSA ♂, ♀ SEM, LM/perm. cPJ Palaeostigus ruficornis schimitscheki (Machulka, 1944) Turkey ♂, ♀ SEM, LM/perm. cPJ Papusus macer Casey, 1897 USA ♂, ♀ SEM, LM/temp. cPJ †Rovnoleptochromus ableptonoides Jałoszyński & Perkovsky, 2016 Eocene of Ukraine ? LM SIZK Stenomastigus varii Leleup, 1968 RSA ♂, ♀ SEM, LM/perm. TMSA Taurablepton asitawandas Besuchet, 1969 Turkey ♀ LM/temp. MHNG Taurablepton sp. Turkey ♂ SEM, LM/temp. cHM * Depository abbreviations: cHM – collection of Heinrich Meybohm, Großhansdorf, Germany. cPJ – collection of Paweł Jałoszyński, Wrocław, Poland. AMNH – American Museum of Natural History, New York, USA. CCHH/SDEI – collection of Christel & Hans Werner Hoffeins, Hamburg, Germany, with final depository at the Senckenberg Deutsches Entomologisches Institut Müncheberg, Germany. FMNH – Field Museum of Natural History, Chicago, USA. MNHW – Museum of Natural History, University of Wrocław, Wrocław, Poland. NHMW – Naturhistorisches Museum Wien, Vienna, Austria. NIGP – Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, China. RMCA – Musée Royal de l’Afrique Centrale, Tervuren, Belgium. SIZK – Schmalhausen Institute of Zoology, National Academy of Sciences of Ukraine, Kiev, Ukraine. TGEM – Three Gorges Entomological Museum, Chongqing, China. TMSA – Ditsong National Museum of National History, Pretoria, RSA. View Large Terminal taxon Country of origin Sex Study method Depository* Euaesthetinae Euaesthetus ruficapillus (Lacordaire, 1835) Poland ♂, ♀ SEM, LM/perm. cPJ Scydmaeninae: Scydmaenini Adrastia edwardsi (Sharp, 1874) New Zealand ♂ LM/temp. NHMW Pseudoeudesis sulcipennis (Reitter, 1890) Tunisia ♂, ♀ LM/temp. MNHW Scydmaenus tarsatus Müller & Kunze, 1822 Poland ♂, ♀ SEM, LM/perm. cPJ Scydmaeninae: Mastigitae Ablepton trefortiFrivaldszky, 1877 Romania ♂, ♀ SEM, LM/perm. cPJ †Baltostigus antennatus Jałoszyński, 2016 Eocene of Poland ♂ μCT, LM CCHH/SDEI †Baltostigus horribilis Jałoszyński, 2016 Eocene of Lithuania ? LM FMNH †Baltostigus striatipennis sp. nov. (AMNH Bu-SY18) Eocene of Russia ♀ μCT, LM AMNH †Cascomastigus monstrabilis Yin & Cai, 2017 Cenomanian of Myanmar HT ♂, PT ♀ Yin et al., 2017 †Clidicostigus arachnipes Jałoszyński et al., 2017 Cenomanian of Myanmar HT ♂ μCT, LM TGEM Clidicus bellator Jałoszyński et al., 2003 Vietnam PT ♂, PT ♀ SEM, LM/perm. cPJ Clidicus formicarius Pascoe, 1866 Borneo ♂, ♀ SEM, LM cPJ †Cretoleptochromus archaicus Cai & Huang, 2016 Cenomanian of Myanmar HT? LM NIGP †Cretoleptochromus burmiticus Yin et al., 2017 Cenomanian of Myanmar HT ♂, PT ♂, PT ♀ Yin et al., 2017 †Cretoleptochromus sp. (AMNH Bu-SY17) Cenomanian of Myanmar ♂ LM AMNH †Euroleptochromus sabathi Jałoszyński, 2012 Eocene of Lithuania HT ♀ LM FMNH †Euroleptochromus setifer sp. nov. (CCHH 835-3) Eocene of Russia HT ♀, PT ♀ μCT, LM CCHH/SDEI Leptochromus agilis (Sharp, 1887) Costa Rica ♂, ♀ LM/temp. MHNG Leptochromus laselva Lord et al., 2014 Costa Rica PT ♂, PT ♀ SEM, LM/temp. cPJ Leptomastax stussineri Reitter, 1880 Bulgaria ♂, ♀ SEM, LM/perm. cPJ Mastigus spinicornis (Fabricius, 1787) RSA ♂, ♀ LM/temp. RMCA †Palaeoleptochromus schaufussi O’Keefe, 1997 Campanian of Canada ♀ O’Keefe et al., 1997 Palaeostigus bifoveolatus (Boheman, 1851) RSA ♂, ♀ SEM, LM/perm. cPJ Palaeostigus ruficornis schimitscheki (Machulka, 1944) Turkey ♂, ♀ SEM, LM/perm. cPJ Papusus macer Casey, 1897 USA ♂, ♀ SEM, LM/temp. cPJ †Rovnoleptochromus ableptonoides Jałoszyński & Perkovsky, 2016 Eocene of Ukraine ? LM SIZK Stenomastigus varii Leleup, 1968 RSA ♂, ♀ SEM, LM/perm. TMSA Taurablepton asitawandas Besuchet, 1969 Turkey ♀ LM/temp. MHNG Taurablepton sp. Turkey ♂ SEM, LM/temp. cHM Terminal taxon Country of origin Sex Study method Depository* Euaesthetinae Euaesthetus ruficapillus (Lacordaire, 1835) Poland ♂, ♀ SEM, LM/perm. cPJ Scydmaeninae: Scydmaenini Adrastia edwardsi (Sharp, 1874) New Zealand ♂ LM/temp. NHMW Pseudoeudesis sulcipennis (Reitter, 1890) Tunisia ♂, ♀ LM/temp. MNHW Scydmaenus tarsatus Müller & Kunze, 1822 Poland ♂, ♀ SEM, LM/perm. cPJ Scydmaeninae: Mastigitae Ablepton trefortiFrivaldszky, 1877 Romania ♂, ♀ SEM, LM/perm. cPJ †Baltostigus antennatus Jałoszyński, 2016 Eocene of Poland ♂ μCT, LM CCHH/SDEI †Baltostigus horribilis Jałoszyński, 2016 Eocene of Lithuania ? LM FMNH †Baltostigus striatipennis sp. nov. (AMNH Bu-SY18) Eocene of Russia ♀ μCT, LM AMNH †Cascomastigus monstrabilis Yin & Cai, 2017 Cenomanian of Myanmar HT ♂, PT ♀ Yin et al., 2017 †Clidicostigus arachnipes Jałoszyński et al., 2017 Cenomanian of Myanmar HT ♂ μCT, LM TGEM Clidicus bellator Jałoszyński et al., 2003 Vietnam PT ♂, PT ♀ SEM, LM/perm. cPJ Clidicus formicarius Pascoe, 1866 Borneo ♂, ♀ SEM, LM cPJ †Cretoleptochromus archaicus Cai & Huang, 2016 Cenomanian of Myanmar HT? LM NIGP †Cretoleptochromus burmiticus Yin et al., 2017 Cenomanian of Myanmar HT ♂, PT ♂, PT ♀ Yin et al., 2017 †Cretoleptochromus sp. (AMNH Bu-SY17) Cenomanian of Myanmar ♂ LM AMNH †Euroleptochromus sabathi Jałoszyński, 2012 Eocene of Lithuania HT ♀ LM FMNH †Euroleptochromus setifer sp. nov. (CCHH 835-3) Eocene of Russia HT ♀, PT ♀ μCT, LM CCHH/SDEI Leptochromus agilis (Sharp, 1887) Costa Rica ♂, ♀ LM/temp. MHNG Leptochromus laselva Lord et al., 2014 Costa Rica PT ♂, PT ♀ SEM, LM/temp. cPJ Leptomastax stussineri Reitter, 1880 Bulgaria ♂, ♀ SEM, LM/perm. cPJ Mastigus spinicornis (Fabricius, 1787) RSA ♂, ♀ LM/temp. RMCA †Palaeoleptochromus schaufussi O’Keefe, 1997 Campanian of Canada ♀ O’Keefe et al., 1997 Palaeostigus bifoveolatus (Boheman, 1851) RSA ♂, ♀ SEM, LM/perm. cPJ Palaeostigus ruficornis schimitscheki (Machulka, 1944) Turkey ♂, ♀ SEM, LM/perm. cPJ Papusus macer Casey, 1897 USA ♂, ♀ SEM, LM/temp. cPJ †Rovnoleptochromus ableptonoides Jałoszyński & Perkovsky, 2016 Eocene of Ukraine ? LM SIZK Stenomastigus varii Leleup, 1968 RSA ♂, ♀ SEM, LM/perm. TMSA Taurablepton asitawandas Besuchet, 1969 Turkey ♀ LM/temp. MHNG Taurablepton sp. Turkey ♂ SEM, LM/temp. cHM * Depository abbreviations: cHM – collection of Heinrich Meybohm, Großhansdorf, Germany. cPJ – collection of Paweł Jałoszyński, Wrocław, Poland. AMNH – American Museum of Natural History, New York, USA. CCHH/SDEI – collection of Christel & Hans Werner Hoffeins, Hamburg, Germany, with final depository at the Senckenberg Deutsches Entomologisches Institut Müncheberg, Germany. FMNH – Field Museum of Natural History, Chicago, USA. MNHW – Museum of Natural History, University of Wrocław, Wrocław, Poland. NHMW – Naturhistorisches Museum Wien, Vienna, Austria. NIGP – Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, China. RMCA – Musée Royal de l’Afrique Centrale, Tervuren, Belgium. SIZK – Schmalhausen Institute of Zoology, National Academy of Sciences of Ukraine, Kiev, Ukraine. TGEM – Three Gorges Entomological Museum, Chongqing, China. TMSA – Ditsong National Museum of National History, Pretoria, RSA. View Large APPENDIX 2 Morphological data matrix for phylogenetic analysis of the supertribe Mastigitae 0000000000 1111111111 2222222222 3333333333 4444444444 5555555555 666666666 0123456789 0123456789 0123456789 0123456789 0123456789 0123456789 012345678 Euaesthetus ruficapillus 0011000000 0–01000000 10––100000 0–110010000 1011000000 000000000 1–0000001 Scydmaenus tarsatus 0000000000 0–00110000 10––111010 0–010000000 1010010000 000000000 1–1110001 Adrastia edwardsi 0000000000 0–01010000 10––111010 0–0100001– 0101001001 0000000000 1–0110001 Pseudoeudesis sulcipennis 0000000000 0–1–0?0000 10––111010 0–01001000 0101000001 0000000000 1–1110001 Ablepton treforti 1000000110 0–11100001 10––0001200–1100010 1110010001 1111010000 1010010000 Taurablepton asitawandas 1010000110 0–1–100001 10––0001200–1100110 1110010000 1111010000 000001???? Taurablepton sp. 1010000110 0–1–100001 10––0001200–1100110 1110010000 1111010000 0000010000 Leptomastax stussineri 1020000110 0–11100001 10––0001200–1100110 1110010000 1111010000 0010010000 Palaeostigus ruficornis 0000011010 0–00110000 010111122 1110111000 1111011110 0000100001 0000001111 Palaeostigus bifoveolatus 0000011010 0–00110000 010111122 1110111000 1111011110 0000100001 0000001111 Stenomastigus varii 0000011010 0–00110000 0101111221110111001–001111110 0000100001 0000001111 Mastigus spinicornis 0000011010 0–00110000 010111122 1110111000 1001111110 0000100001 0000001111 Clidicostigus arachnipes 00000??010 0–00110100 01001?1221 1101???0?? ?????????? ?????000?? 0–0????1? Cascomastigus monstrabilis 000????010 0–00?10100 01001?1221 1101?????? ?????????? ?????000?? 0–0?????? Clidicus bellator 0111101010 0–01010101 10––100120 0–0000001– 110001000 1001100010 0010010001 Clidicus formicarius 0101101011 0–01110111 10––100220 100000001– 110001000 1001100010 0010010001 Papusus macer 0011101010 0–01110000 10––101120 0–0100001–11010??00 0000010000 0000000001 Palaeoleptochromus schaufussi 0?21?01111 0–01??0011 10––1?0220 100????0?? ?????????? ??????01?? ?–??????? Leptochromus agilis 0001101011 1001111100 0101100220 0–0000100 1110101000 0110101100 0010000001 Leptochromus laselva 0001101011 1101111100 0101100220 0–0000100 1110101000 0110101100 0010000001 Euroleptochromus sabathi 0001?01011 1101??1100 11011?0220 0–000?10? ??10?0?000 0??0001100 0010?????? Euroleptochromus setifer 0001101011 1101??1100 1101100220 0–0000100 1?1000?000 0??0001100 0010?????? Baltostigus horribilis 0000100010 0–01?1001 001111?122 11101???0? ??????1100 0??0000000 0000?????? Baltostigus antennatus 0000100010 0–01??001 001111?122 11101???0? ?????????0 ???0??0000 ?010?1??01 Baltostigus striatipennis 0000100010 0–0111001 001111?122 11101??00? ??00101100 0??0000000 0010?????? Rovnoleptochromus ableptonoides 0001?0?011 0–01110101 0101100220 0–00???0? ???0?1?001 ???0001000 1010?????? Cretoleptochromus archaicus 0111101011 0–0111011? ?0––10022 01000?000? ??10?0?001 ???1100010 0010?????? Cretoleptochromus burmiticus 0121?0?011 0–01110110 10––1?022 01000?010? ?????????? ?????0001? ?010?1??0? Cretoleptochromus sp. 01111?101? 0–01110111 10––1?0220 1000???0? ?????????0? ??11000?00 010?1??11 0000000000 1111111111 2222222222 3333333333 4444444444 5555555555 666666666 0123456789 0123456789 0123456789 0123456789 0123456789 0123456789 012345678 Euaesthetus ruficapillus 0011000000 0–01000000 10––100000 0–110010000 1011000000 000000000 1–0000001 Scydmaenus tarsatus 0000000000 0–00110000 10––111010 0–010000000 1010010000 000000000 1–1110001 Adrastia edwardsi 0000000000 0–01010000 10––111010 0–0100001– 0101001001 0000000000 1–0110001 Pseudoeudesis sulcipennis 0000000000 0–1–0?0000 10––111010 0–01001000 0101000001 0000000000 1–1110001 Ablepton treforti 1000000110 0–11100001 10––0001200–1100010 1110010001 1111010000 1010010000 Taurablepton asitawandas 1010000110 0–1–100001 10––0001200–1100110 1110010000 1111010000 000001???? Taurablepton sp. 1010000110 0–1–100001 10––0001200–1100110 1110010000 1111010000 0000010000 Leptomastax stussineri 1020000110 0–11100001 10––0001200–1100110 1110010000 1111010000 0010010000 Palaeostigus ruficornis 0000011010 0–00110000 010111122 1110111000 1111011110 0000100001 0000001111 Palaeostigus bifoveolatus 0000011010 0–00110000 010111122 1110111000 1111011110 0000100001 0000001111 Stenomastigus varii 0000011010 0–00110000 0101111221110111001–001111110 0000100001 0000001111 Mastigus spinicornis 0000011010 0–00110000 010111122 1110111000 1001111110 0000100001 0000001111 Clidicostigus arachnipes 00000??010 0–00110100 01001?1221 1101???0?? ?????????? ?????000?? 0–0????1? Cascomastigus monstrabilis 000????010 0–00?10100 01001?1221 1101?????? ?????????? ?????000?? 0–0?????? Clidicus bellator 0111101010 0–01010101 10––100120 0–0000001– 110001000 1001100010 0010010001 Clidicus formicarius 0101101011 0–01110111 10––100220 100000001– 110001000 1001100010 0010010001 Papusus macer 0011101010 0–01110000 10––101120 0–0100001–11010??00 0000010000 0000000001 Palaeoleptochromus schaufussi 0?21?01111 0–01??0011 10––1?0220 100????0?? ?????????? ??????01?? ?–??????? Leptochromus agilis 0001101011 1001111100 0101100220 0–0000100 1110101000 0110101100 0010000001 Leptochromus laselva 0001101011 1101111100 0101100220 0–0000100 1110101000 0110101100 0010000001 Euroleptochromus sabathi 0001?01011 1101??1100 11011?0220 0–000?10? ??10?0?000 0??0001100 0010?????? Euroleptochromus setifer 0001101011 1101??1100 1101100220 0–0000100 1?1000?000 0??0001100 0010?????? Baltostigus horribilis 0000100010 0–01?1001 001111?122 11101???0? ??????1100 0??0000000 0000?????? Baltostigus antennatus 0000100010 0–01??001 001111?122 11101???0? ?????????0 ???0??0000 ?010?1??01 Baltostigus striatipennis 0000100010 0–0111001 001111?122 11101??00? ??00101100 0??0000000 0010?????? Rovnoleptochromus ableptonoides 0001?0?011 0–01110101 0101100220 0–00???0? ???0?1?001 ???0001000 1010?????? Cretoleptochromus archaicus 0111101011 0–0111011? ?0––10022 01000?000? ??10?0?001 ???1100010 0010?????? Cretoleptochromus burmiticus 0121?0?011 0–01110110 10––1?022 01000?010? ?????????? ?????0001? ?010?1??0? Cretoleptochromus sp. 01111?101? 0–01110111 10––1?0220 1000???0? ?????????0? ??11000?00 010?1??11 ‘–’ indicates inapplicable characters. ‘?’ indicates missing data. View Large 0000000000 1111111111 2222222222 3333333333 4444444444 5555555555 666666666 0123456789 0123456789 0123456789 0123456789 0123456789 0123456789 012345678 Euaesthetus ruficapillus 0011000000 0–01000000 10––100000 0–110010000 1011000000 000000000 1–0000001 Scydmaenus tarsatus 0000000000 0–00110000 10––111010 0–010000000 1010010000 000000000 1–1110001 Adrastia edwardsi 0000000000 0–01010000 10––111010 0–0100001– 0101001001 0000000000 1–0110001 Pseudoeudesis sulcipennis 0000000000 0–1–0?0000 10––111010 0–01001000 0101000001 0000000000 1–1110001 Ablepton treforti 1000000110 0–11100001 10––0001200–1100010 1110010001 1111010000 1010010000 Taurablepton asitawandas 1010000110 0–1–100001 10––0001200–1100110 1110010000 1111010000 000001???? Taurablepton sp. 1010000110 0–1–100001 10––0001200–1100110 1110010000 1111010000 0000010000 Leptomastax stussineri 1020000110 0–11100001 10––0001200–1100110 1110010000 1111010000 0010010000 Palaeostigus ruficornis 0000011010 0–00110000 010111122 1110111000 1111011110 0000100001 0000001111 Palaeostigus bifoveolatus 0000011010 0–00110000 010111122 1110111000 1111011110 0000100001 0000001111 Stenomastigus varii 0000011010 0–00110000 0101111221110111001–001111110 0000100001 0000001111 Mastigus spinicornis 0000011010 0–00110000 010111122 1110111000 1001111110 0000100001 0000001111 Clidicostigus arachnipes 00000??010 0–00110100 01001?1221 1101???0?? ?????????? ?????000?? 0–0????1? Cascomastigus monstrabilis 000????010 0–00?10100 01001?1221 1101?????? ?????????? ?????000?? 0–0?????? Clidicus bellator 0111101010 0–01010101 10––100120 0–0000001– 110001000 1001100010 0010010001 Clidicus formicarius 0101101011 0–01110111 10––100220 100000001– 110001000 1001100010 0010010001 Papusus macer 0011101010 0–01110000 10––101120 0–0100001–11010??00 0000010000 0000000001 Palaeoleptochromus schaufussi 0?21?01111 0–01??0011 10––1?0220 100????0?? ?????????? ??????01?? ?–??????? Leptochromus agilis 0001101011 1001111100 0101100220 0–0000100 1110101000 0110101100 0010000001 Leptochromus laselva 0001101011 1101111100 0101100220 0–0000100 1110101000 0110101100 0010000001 Euroleptochromus sabathi 0001?01011 1101??1100 11011?0220 0–000?10? ??10?0?000 0??0001100 0010?????? Euroleptochromus setifer 0001101011 1101??1100 1101100220 0–0000100 1?1000?000 0??0001100 0010?????? Baltostigus horribilis 0000100010 0–01?1001 001111?122 11101???0? ??????1100 0??0000000 0000?????? Baltostigus antennatus 0000100010 0–01??001 001111?122 11101???0? ?????????0 ???0??0000 ?010?1??01 Baltostigus striatipennis 0000100010 0–0111001 001111?122 11101??00? ??00101100 0??0000000 0010?????? Rovnoleptochromus ableptonoides 0001?0?011 0–01110101 0101100220 0–00???0? ???0?1?001 ???0001000 1010?????? Cretoleptochromus archaicus 0111101011 0–0111011? ?0––10022 01000?000? ??10?0?001 ???1100010 0010?????? Cretoleptochromus burmiticus 0121?0?011 0–01110110 10––1?022 01000?010? ?????????? ?????0001? ?010?1??0? Cretoleptochromus sp. 01111?101? 0–01110111 10––1?0220 1000???0? ?????????0? ??11000?00 010?1??11 0000000000 1111111111 2222222222 3333333333 4444444444 5555555555 666666666 0123456789 0123456789 0123456789 0123456789 0123456789 0123456789 012345678 Euaesthetus ruficapillus 0011000000 0–01000000 10––100000 0–110010000 1011000000 000000000 1–0000001 Scydmaenus tarsatus 0000000000 0–00110000 10––111010 0–010000000 1010010000 000000000 1–1110001 Adrastia edwardsi 0000000000 0–01010000 10––111010 0–0100001– 0101001001 0000000000 1–0110001 Pseudoeudesis sulcipennis 0000000000 0–1–0?0000 10––111010 0–01001000 0101000001 0000000000 1–1110001 Ablepton treforti 1000000110 0–11100001 10––0001200–1100010 1110010001 1111010000 1010010000 Taurablepton asitawandas 1010000110 0–1–100001 10––0001200–1100110 1110010000 1111010000 000001???? Taurablepton sp. 1010000110 0–1–100001 10––0001200–1100110 1110010000 1111010000 0000010000 Leptomastax stussineri 1020000110 0–11100001 10––0001200–1100110 1110010000 1111010000 0010010000 Palaeostigus ruficornis 0000011010 0–00110000 010111122 1110111000 1111011110 0000100001 0000001111 Palaeostigus bifoveolatus 0000011010 0–00110000 010111122 1110111000 1111011110 0000100001 0000001111 Stenomastigus varii 0000011010 0–00110000 0101111221110111001–001111110 0000100001 0000001111 Mastigus spinicornis 0000011010 0–00110000 010111122 1110111000 1001111110 0000100001 0000001111 Clidicostigus arachnipes 00000??010 0–00110100 01001?1221 1101???0?? ?????????? ?????000?? 0–0????1? Cascomastigus monstrabilis 000????010 0–00?10100 01001?1221 1101?????? ?????????? ?????000?? 0–0?????? Clidicus bellator 0111101010 0–01010101 10––100120 0–0000001– 110001000 1001100010 0010010001 Clidicus formicarius 0101101011 0–01110111 10––100220 100000001– 110001000 1001100010 0010010001 Papusus macer 0011101010 0–01110000 10––101120 0–0100001–11010??00 0000010000 0000000001 Palaeoleptochromus schaufussi 0?21?01111 0–01??0011 10––1?0220 100????0?? ?????????? ??????01?? ?–??????? Leptochromus agilis 0001101011 1001111100 0101100220 0–0000100 1110101000 0110101100 0010000001 Leptochromus laselva 0001101011 1101111100 0101100220 0–0000100 1110101000 0110101100 0010000001 Euroleptochromus sabathi 0001?01011 1101??1100 11011?0220 0–000?10? ??10?0?000 0??0001100 0010?????? Euroleptochromus setifer 0001101011 1101??1100 1101100220 0–0000100 1?1000?000 0??0001100 0010?????? Baltostigus horribilis 0000100010 0–01?1001 001111?122 11101???0? ??????1100 0??0000000 0000?????? Baltostigus antennatus 0000100010 0–01??001 001111?122 11101???0? ?????????0 ???0??0000 ?010?1??01 Baltostigus striatipennis 0000100010 0–0111001 001111?122 11101??00? ??00101100 0??0000000 0010?????? Rovnoleptochromus ableptonoides 0001?0?011 0–01110101 0101100220 0–00???0? ???0?1?001 ???0001000 1010?????? Cretoleptochromus archaicus 0111101011 0–0111011? ?0––10022 01000?000? ??10?0?001 ???1100010 0010?????? Cretoleptochromus burmiticus 0121?0?011 0–01110110 10––1?022 01000?010? ?????????? ?????0001? ?010?1??0? Cretoleptochromus sp. 01111?101? 0–01110111 10––1?0220 1000???0? ?????????0? ??11000?00 010?1??11 ‘–’ indicates inapplicable characters. ‘?’ indicates missing data. View Large APPENDIX 3 Characters and character states included in phylogenetic analysis 0. Modified, broadened and flattened setae on thorax and antennae: (0) absent; (1) present. 1. Setae on frons and vertex: (0) approximately uniform in length; (1) some setae conspicuously long and erect among much shorter and denser basic vestiture. 2. Broadest site of head capsule: (0) near middle; (1) in posterior half; (2) in anterior half. 3. Anterior margin of frons between antennal insertions: (0) subtriangular, distinctly expanded anteriorly at middle; (1) straight or indistinctly arcuate. 4. Frontoclypeal groove: (0) marked only at middle; (1) extending over entire width of head capsule. 5. Median longitudinal groove on vertex: (0) absent; (1) present. 6. Posteromedian impression on vertex: (0) absent; (1) present. 7. Posterior margin of vertex: (0) lacking a pair of enlarged lateral setae or conspicuous chaetopores; (1) with a pair of distinctly enlarged lateral setae, clearly different from surrounding setae, or with a pair of conspicuous chaetopores. 8. Antennal insertions: (0) adjacent to mandibular bases; (1) clearly separated from mandibular bases. 9. Postgenal (subocular) bristles: (0) absent; (1) present. 10. Postgenal process: (0) absent; (1) present. 11. Shape of postgenal process: (0) short, tuberculate; (1) strongly elongate. 12. Compound eyes: (0) large, composed of at least several dozen ommatidia; (1) rudimentary, composed of one to several ommatidia, or absent. 13. Placement of eyes: (0) adjacent to antennal insertions; (1) separated (sometimes narrowly) from antennal insertions. 14. Labrum: (0) with anterior margin straight or arcuate; (1) with anteromedian emargination (sometimes with an additional narrow median projection). 15. Mandible: (0) lacking preapical teeth or, if teeth present, then located strictly mesally in same plane as apical tooth; (1) with at least one preapical tooth located and directed dorsomesally, above plane of mandible. 16. Setal process on maxillary palpomere 2: (0) absent; (1) present. 17. Setae on maxillary palpomere 2: (0) uniform; (1) at least a few remarkably long, erect and often thickened setae or thick bristles on anteroventral surface among shorter and/or suberect or recumbent basic vestiture. 18. Setae on maxillary palpomere 3: (0) uniform; (1) sparse, long and strongly erect setae (often thickened) present among basic recumbent or suberect vestiture. 19. Distal margin of maxillary palpomere 3: (0) approximately perpendicular to long axis of palpomere; (1) distinctly, often strongly, oblique. 20. Relative width of maxillary palpomere 4: (0) broader than 3; (1) narrower than 3. 21. Palpomere 4: (0) narrowing from base to apex; (1) broadening distad, at least in basal half. 22. Broadened palpomere 4: (0) weakly, often only slightly broadened and elongate; (1) strongly broadened, broader than long, axe-shaped. 23. Weakly broadened palpomere 4: (0) curved (i.e. with one side convex and the opposite concave); (1) not curved (i.e. with both sides nearly straight or convex). 24. Maxillary palpomeres 3 + 4: (0) with lateral margins confluent, palpomeres together forming compact oval; (1) with lateral margins not confluent. 25. Insertions of labial palps: (0) broadly separated (by more than maximum width of palpomere 1); (1) approximate (closer together than maximum width of palpomere 1). 26. Distance between antennal insertions: (0) at least twice as wide as antennal cavity; (1) about as wide as antennal cavity or narrower. 27. Length of scape: (0) much shorter than head capsule; (1) about as long as head capsule or slightly longer; (2) much longer than head capsule. 28. Antennae: (0) cannot bend between scape and pedicel; (1) can bend dorsad or dorsolaterad between scape and pedicel; (2) can bend ventrad or ventrolaterad between scape and pedicel. 29. Pedicel: (0) short, not conspicuously enlarged, lacking ventral rows of bristles; (1) strikingly elongated, much longer than subsequent antennomeres and with ventral bristles arranged in rows. 30. Bristles on scape: (0) absent, vestiture of scape relatively uniform; (1) present, strongly erect, long and directed ventrad (slightly or much thicker than basic vestiture of scape). 31. Arrangement of bristles on scape: (0) unordered; (1) ordered in two longitudinal rows. 32. Flagellomeres (except 11): (0) all or nearly all elongate; (1) mostly broader than long or some about as long as broad. 33. Posterior pronotal collar: (0) distinct, demarcated from disc by transverse groove or impressed row of pits and variously distinct constriction; (1) absent. 34. Procoxal cavities: (0) broadly open posteriorly; (1) delimited posteriorly by hypomeral lobes strongly projecting mesad. 35. Procoxal cavities: (0) distinctly demarcated from basisternum by arcuate ridges; (1) anteriorly confluent with basisternum. 36. Basisternal and coxal parts of prosternum: (0) subequal in length; (1) basisternal part much longer (1.5 times and more) than coxal part. 37. Vestiture of basisternal part of prosternum: (0) approximately uniform; (1) composed of two rows of setae extending along anterior and posterior margin and largely or completely asetose in between. 38. Anterior ridge of mesoventrite: (0) with posteromedian subtriangular projection or expansion; (1) lacking posteromedian projection. 39. Posteromedian projection of anterior ridge of mesoventrite: (0) posteriorly connected with mesoventral intercoxal process; (1) posteriorly demarcated from mesoventral intercoxal process. 40. Transverse impression filled with setae on mesoventrite: (0) absent; (1) present. 41. Median region of mesoventrite anterior to mesocoxal cavities: (0) with conspicuously large, evenly and weakly convex area about as long as broad; (1) lacking such area. 42. Mesoventral intercoxal process: (0) slender and narrow, much longer than broad; (1) stout, about as long as broad. 43. Median subtriangular convexity of anterior mesoventral region: (0) present; (1) absent. 44. Lateral margins of mesoventral intercoxal process between mesocoxae: (0) subparallel; (1) convergent posteriorly. 45. Sharp anterior carina of mesocoxal cavities confluent with lateral margin of mesoventral process: (0) present; (1) absent. 46. Posterior margin of mesocoxal cavities: (0) carinate (at least partly); (1) non-carinate. 47. Metaventrite: (0) broadest near posterior third or between middle and posterior third, distinctly narrowing toward metacoxae; (1) broadest at or just in front of metacoxae. 48. Median longitudinal metaventral carina: (0) absent; (1) present. 49. Dorsolateral fovea (i.e. laterad mesepimeron + mesanepisternum and directed mesally): (0) absent; (1) present. 50. Postmesocoxal metaventral fovea (at posterior or posterolateral margin of mesocoxal cavity and directed mesally or anteromesally): (0) absent; (1) present. 51. Fovea at lateral margin of mesocoxal cavity directed anterolaterally: (0) absent; (1) present. 52. Anterior margin of katepisternum: (0) not marked; (1) distinctly marked as arcuate groove extending along lateroanterior margin of metacoxa. 53. Admetacoxal margin of metaventrite: (0) concave, lacking angulate expansion; (1) with angulate expansion. 54. Row of several (3–6) thick bristles (conspicuously thicker than basic vestiture of coxa) on ventral surface of mesocoxa: (0) absent; (1) present. 55. Protrochanteral ventral comb of several (2–7) thick bristles: (0) absent; (1) present. 56. Profemoral ventral comb of several thick bristles: (0) absent; (1) present. 57. One or two conspicuously long and erect ventral setae in basal half of profemur: (0) absent; (1) present. 58. Suture between metaventrite and first visible abdominal sternite: (0) distinct; (1) nearly obliterated, abdominal sternite fused medially with posterior margin of metaventrite. 59. Transverse, broadly and inversely V-shaped median ridge on abdominal sternite 3: (0) absent; (1) present. 60. Elytral disc: (0) with punctures arranged in longitudinal rows or with impressed longitudinal striae; (1) with punctures not arranged in rows. 61. Longitudinal rows of elytral punctures: (0) fine and barely discernible, nearly lost among fine unordered punctures or microsculpture; (1) distinct, composed of conspicuously large punctures, often connected by impressed striae. 62. Basal elytral foveae: (0) absent; (1) present. 63. Median longitudinal impression on propygidium: (0) absent; (1) present. 64. Posterior margin of abdominal sternite 8 in males: (0) distinctly emarginate; (1) rounded or truncate. 65. Flagellum: (0) short and straight or C-shaped, but not looped; (1) very long, forming several loops. 66. Permanently everted membranous apical part of copulatory piece: (0) absent; (1) present. 67. Parameres: (0) symmetrical or nearly symmetrical; (1) asymmetrical, one paramere shorter than the other one. 68. Apices of parameres: (0) abruptly and strongly bent mesally; (1) not bent mesally, at most evenly and slightly curved toward middle. REFERENCES Aitchison JC , Ali JR , Davis AM . 2007 . When and where did India and Asia collide ? Journal of Geophysical Research 112 : doi: 10.1029/2006JB004706 . de Bruyn M , Stelbrink B , Morley RJ , Hall R , Carvalho GR , Cannon CH , van den Bergh G , Meijaard E , Metcalfe I , Boitani L , Maiorano L , Shoup R , von Rintelen T . 2014 . Borneo and Indochina are major evolutionary hotspots for Southeast Asian biodiversity . Systematic Biology 63 : 879 – 901 . Google Scholar CrossRef Search ADS PubMed Cai C-Y , Huang D-Y . 2016 . Cretoleptochromus archaicus gen. et sp. nov., a new genus of ant-like stone beetles in Upper Cretaceous Burmese amber (Coleoptera, Staphylinidae, Scydmaeninae) . Cretaceous Research 63 : 7 – 13 . Google Scholar CrossRef Search ADS Casey TL . 1897 . Coleopterological notices, VII . Annals of the New York Academy of Science 9 : 285 – 684 . Google Scholar CrossRef Search ADS Castellini G . 1996 [1994] . Revisione del genre Leptomastax Pirazzoli, 1855 (Coleoptera, Scydmaenidae) . Atti del Museo Civico di Storia Naturale di Grosseto 15 : 1 – 137 . Endrödy-Younga S . 1978 . Coleoptera . In: Werger MJA , Van Bruggen AC , eds. Biogeography and ecology of Southern Africa . Hague : W. Junk Publishers , 797 – 821 . Google Scholar CrossRef Search ADS Fleming J . 1821 . Insecta. supplement to the fourth, fifth and sixth editions of the encyclopaedia Britannica , Vol. 5[Part 1]. Edinburgh : A. Constable and Company , pp. 41 – 56 . Franz H . 1985 . Revision Caseyscher Scydmaenidentypen . Sitzungsberichte der Österreichischen Akademie der Wissenschaften, Mathematisch-Naturwissenschaftliche Klasse, Abteilung I 194 : 149 – 186 . Frivaldszky J . 1877 . Coleoptera Nova e hungaria meridionale . Természetrajzi Füzetek 1 : 17 – 22 . Goloboff P , Farris J , Nixon K . 2008 . TNT, a free program for phylogenetic analysis . Cladistics 24 : 774 – 786 . Google Scholar CrossRef Search ADS Grebennikov VV , Newton AF . 2009 . Good-bye Scydmaenidae, or why the ant-like stone beetles should become megadiverse Staphylinidae sensu latissimo (Coleoptera) . European Journal of Entomology 106 : 275 – 301 . Google Scholar CrossRef Search ADS Hadley A . 2010 . Combine ZP software, new version, [WWW document] . URL http://www.hadleyweb.pwp.blueyonder.co.uk/CZP/News.htm (currently available at http://combinezp.software.informer.com/) Jałoszyński P . 2012a . Description of Euroleptochromus gen. n. (Coleoptera, Staphylinidae, Scydmaeninae) from Baltic amber, with discussion of biogeography and mouthpart evolution within Clidicini . Systematic Entomology 37 : 346 – 359 . Google Scholar CrossRef Search ADS Jałoszyński P . 2012b . Stenomastigus Leleup (Staphylinidae, Scydmaeninae): status of subgenus Acanthostigus Leleup and revision of species with elongated male protrochanters . Zootaxa 3153 : 39 – 56 . Jałoszyński P . 2012c . Beetles with ‘trochantelli’: phylogeny of Cephenniini (Coleoptera: Staphylinidae: Scydmaeninae) focussing on Neotropical genera . Systematic Entomology 37 : 448 – 477 . Google Scholar CrossRef Search ADS Jałoszyński P . 2016a . Scydmaeninae Leach, 1815 . In: Beutel RG , Leschen RAB , eds. Handbook of zoology, ‘arthropoda: insecta’, coleoptera, beetles. morphology and systematics , Vol. 1 , 2nd edn . Berlin : Walter de Gruyter . Jałoszyński P . 2016b [2015] . A new Eocene genus of ant-like stone beetles sheds new light on the evolution of Mastigini . Journal of Paleontology 89 : 1056 – 1067 . Google Scholar CrossRef Search ADS Jałoszyński P . 2017 . First record of Cephenniini on Christmas Island, with updated checklist of world Cephennomicrus species and summary of their distribution (Coleoptera, Staphylinidae, Scydmaeninae) . Zootaxa 4227 : 593 – 600 . Google Scholar CrossRef Search ADS Jałoszyński P , Hlaváč P , Nomura S . 2003 . Contribution to the knowledge of the genus Clidicus (Coleoptera, Scydmaenidae), with descriptions of four new species from Vietnam and Laos . Bulletin of National Science Museum Tokyo, Ser. A 29 : 21 – 38 . Jałoszyński P , Perkovsky E . 2016 . Diversity of Scydmaeninae (Coleoptera: Staphylinidae) in Upper Eocene Rovno amber . Zootaxa 4157 : 1 – 85 . Google Scholar CrossRef Search ADS PubMed Jałoszyński P , Matsumura Y , Beutel RG . 2015 . Evolution of a giant intromittent organ in Scydmaeninae (Coleoptera: Staphylinidae): functional morphology of the male postabdomen in Mastigini . Arthropod Structure & Development 44 : 77 – 98 . Google Scholar CrossRef Search ADS PubMed Jałoszyński P , Brunke AJ , Metscher B , Zhang W-W , Bai M . 2017a . Clidicostigus gen. nov., the first Mesozoic genus of Mastigini (Coleoptera: Staphylinidae: Scydmaeninae) from Burmese amber . Cretaceous Research 72 : 110 – 116 . Google Scholar CrossRef Search ADS Jałoszyński P , Perrichot V , Peris D . 2017b . Ninety million years of chasing mites by ant-like stone beetles . Gondwana Research 48 : 1 – 6 . Google Scholar CrossRef Search ADS Lacordaire JT . 1835 . In: Boisduval J , Lacordaire , JT , eds. Faune entomologique des environs de Paris: ou species général des insectes qui se trouvent dans un rayon de quinze à vingt lieues aux alentours de Paris . Tome premier. Paris : Méquignon-Marvis , p. 696 . Laporte FL . 1832 . Mémoire sur cinquante espèces nouvelles ou peu connues d’insectes . Annales de la Société Entomologique de France 1 : 386 – 415 . Latreille PA . 1802 . Histoire naturelle, générale et particulière des Crustacés et des Insectes. Familles Naturelles des Genres , Vol. 3 . Paris : F. Dufart , xii + 13 – 467 pp. Leach WE . 1815 . Entomology . In: Brewster D , ed. Brewster’s Edinburgh encyclopedia , Vol. 9[part I]. Edinburgh : W. Blackwood, J. Waugh; London: J. Murray, Baldwin & Cradock, J. M. Richardson; and the other proprietors ., 57 – 172 . Google Scholar CrossRef Search ADS Liu Z , Pagani M , Zinniker D , Deconto R , Huber M , Brinkhuis H , Shah SR , Leckie RM , Pearson A . 2009 . Global cooling during the eocene-oligocene climate transition . Science (New York, NY) 323 : 1187 – 1190 . Google Scholar CrossRef Search ADS Metcalfe I , Smith JMB , Morwood M , Davidson I . 2001 . Faunal and floral migrations and evolution in SE Asia–Australasia . Lisse, Abingdon, Exton, Tokyo : A.A. Balkema Publishers . Maddison WP , Maddison DR . 2017 . Mesquite: a modular system for evolutionary analysis, version 3.2, [WWW document] . URL http://mesquiteproject.org Müller PWI , Kunze G . 1822 . Monographie der Ameisenkäfer (Scydmaenus Latreille) . Schriften der Naturforschenden Gesellschaft zu Leipzig 1 : 175 – 204 . Nixon KC . 1999–2002 . WINCLADA (Beta), 1.00.08. Software published by the author, Ithaca, New York. [WWW document] . URL http://www.cladistics.com (currently available at http://www.diversityoflife.org/winclada/) O’Keefe ST . 1998 . Notes on the classification of North American ant-like stone beetles (Coleoptera: Scydmaenidae) . The Coleopterists Bulletin 52 : 259 – 269 . O’Keefe ST . 2002 . Revision of the Neotropical genus Leptochromus Motschulsky (Coleoptera: Scydmaenidae) . Systematic Entomology 27 : 211 – 234 . Google Scholar CrossRef Search ADS O’Keefe ST . 2003 . Revision of the Nearctic genus Papusus Casey (Coleoptera, Scydmaenidae) . In: Cuccodoro G. , Leschen RAB , eds. Systematics of Coleoptera: papers celebrating the retirement of Ivan Löbl . Gainsville: Memoirs on Entomology International, Associated Publishers 17 : 257 – 309 . O’Keefe ST , Pike T , Poinar G . 1997 . Palaeoleptochromus schaufussi (gen. n., sp. nov.), a new antlike stone beetle (Coleoptera: Scydmaenidae) from Canadian Cretaceous amber . The Canadian Entomologist 129 : 379 – 385 . Google Scholar CrossRef Search ADS Orousset J . 2014 . Contribution à la connaissance du genre Clidicus Laporte de Castelnau, 1832 (Coleoptera, Staphylinidae, Scydmaeninae) . Le Coléoptériste 17 : 116 – 135 . Page RDM . 2001 . NDE: NEXUS Data Editor 0.5.0. University of Glasgow, Glasgow, Scotland, UK [WWW document] . URL http://taxonomy.zoology.gla.ac.uk/rod/NDE/nde.html Pascoe FP . 1866 . Notice on new or little known genera and species of Coleoptera, Part IV . Journal of Entomology 2 : 26 – 56 . Rambaut A , Suchard MA , Xie D , Drummond AJ . 2014 . Tracer v.1.6 457http://beast.bio.ed.ac.uk/Tracer Reitter E . 1890 . Neue Coleopteren aus Europa, den angrenzenden Ländern und Sibirien, mit Bemerkungen über bekannte Arten. Elfter Theil . Deutsche Entomologische Zeitschrift 34 : 385 – 396 . Ronquist F , Teslenko M , Van Der Mark P , Ayres DL , Darling A , Höhna S , Larget B , Liu L , Suchard MA , Huelsenbeck JP . 2012 . MrBayes 3.2: efficient Bayesian phylogenetic inference and model choice across a large model space . Systematic Biology 61 : 539 – 542 . Google Scholar CrossRef Search ADS PubMed Sharp D . 1874 . Descriptions of new genera and species of Pselaphidae and Scydmaenidae from Australia and New Zealand . Transactions of the Entomological Society of London 1874 : 483 – 517 . Whiting MF , Bradler S , Maxwell T . 2003 . Loss and recovery of wings in stick insects . Nature 421 : 264 – 267 . Google Scholar CrossRef Search ADS PubMed Yin Z , Cai C , Huang D , Li L . 2017a . A second species of the genus Cretoleptochromus Cai & Huang (Coleoptera: Staphylinidae: Scydmaeninae) from mid-Cretaceous Burmese amber . Cretaceous Research 75 : 115 – 119 . Google Scholar CrossRef Search ADS Yin ZW , Cai CY , Huang DY , Li LZ . 2017 . Specialized adaptations for springtail predation in Mesozoic beetles . Scientific Reports 7 : 98 . Google Scholar CrossRef Search ADS PubMed Yu Y , Harris AJ , He X . 2010 . S-DIVA (Statistical Dispersal-Vicariance Analysis): a tool for inferring biogeographic histories . Molecular Phylogenetics and Evolution 56 : 848 – 850 . Google Scholar CrossRef Search ADS PubMed Yu Y , Harris AJ , Blair C , He X . 2015 . RASP (Reconstruct Ancestral State in Phylogenies): a tool for historical biogeography . Molecular Phylogenetics and Evolution 87 : 46 – 49 . Google Scholar CrossRef Search ADS PubMed Żyła D , Yamamoto S , Wolf-Schwenninger K , Solodovnikov A . 2017 . Cretaceous origin of the unique prey-capture apparatus in mega-diverse genus: stem lineage of Steninae rove beetles discovered in Burmese amber . Scientific Reports 7 : doi: 10.1038/srep45904 © 2018 The Linnean Society of London, Zoological Journal of the Linnean Society This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices)

Journal

Zoological Journal of the Linnean SocietyOxford University Press

Published: Apr 19, 2018

There are no references for this article.

You’re reading a free preview. Subscribe to read the entire article.


DeepDyve is your
personal research library

It’s your single place to instantly
discover and read the research
that matters to you.

Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.

All for just $49/month

Explore the DeepDyve Library

Search

Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly

Organize

Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.

Access

Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.

Your journals are on DeepDyve

Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.

All the latest content is available, no embargo periods.

See the journals in your area

DeepDyve

Freelancer

DeepDyve

Pro

Price

FREE

$49/month
$360/year

Save searches from
Google Scholar,
PubMed

Create lists to
organize your research

Export lists, citations

Read DeepDyve articles

Abstract access only

Unlimited access to over
18 million full-text articles

Print

20 pages / month

PDF Discount

20% off