A new family of mites (Acari: Prostigmata: Raphignathina), highly specialized subelytral parasites of dytiscid water beetles (Coleoptera: Dytiscidae: Dytiscinae)

A new family of mites (Acari: Prostigmata: Raphignathina), highly specialized subelytral... Abstract A new genus, Dytiscacarus gen nov. Hajiqanbar and Lindquist, based on three new species and representing a new family of trombidiform mites, is described from Iran and the USA. These mites are highly specialized parasites of beetles in the family Dytiscidae, undergoing their entire life cycle while inhabiting the space beneath the elytra of their hosts. The new taxon is autapomorphic in three aspects, characteristic of all active instars: a pair of gnathosomatic neostigmata on the dorsal face of the infracapitulum, the morphological arrangement of the deeply retractable cheliceral stylets, and the pretarsi of all legs lacking an empodium and bearing paired claws strongly modified into sclerotized tenent-like structures. This lineage is unique among parasitic mites in there being no previous records of aquatic beetles harbouring all instars of a highly specialized mite. The age of this mite–insect association may go back to nearly 110–90 Mya. Placement of the new taxon in the cohort (or hyporder) Raphignathina is discussed. Invertebrate parasitism in the supercohort (or infraorder) Eleutherengonides, aquatic beetles harbouring the new taxon of parasitic mites, and the dispersal and host transfer of these mites are reviewed and discussed. Acariformes, Dytiscacaridae, ectoparasite, Hydaticus, Nearctic, Palaearctic, systematics, Thermonectus INTRODUCTION The lives of organisms are not isolated, and close relationships may be observed among a collection of phylogenetically close or remote species, often ascertained as symbioses. Symbiotic associations are not only ubiquitous in nature, but may also play basic roles in ecology and evolution. These associations may last for the lifetimes of one or all parties but also include temporary relationships (Dimijian, 2000; Sapp, 2004; Leung & Poulin, 2008). Symbioses are often categorized as mutualistic, commensal or parasitic. Although extreme specialization occurs among commensal and mutualistic symbionts that complete their development on a single host individual, this pattern is most evident among parasites, a group of organisms with a highly specialized life history that is a consistent element of natural ecosystems and represent a proportional role or impact in causing co-evolutionary trends. In the context of conservation biology, parasites represent a large proportion of the living organisms on Earth; > 50% of all species (Loker & Hofkin, 2015). According to Matthews (1998), parasitic organisms outnumber free-living organisms, and some authors even suggest ratios as high as four parasites for every one free-living organism (Zimmer, 2001). Research projects in parasitology are mostly focused on control of parasites of humans and domesticated animals. However, general progress in parasitology could be accelerated if more studies were made of parasites that use invertebrates as definitive hosts (Wilson, Ivanova & Spiridonov, 2015). Mites are composed of two ancient and exceedingly diverse groups (Parasitiformes and Acariformes) of arachnids (Arthropoda: Arachnida) that include many parasites, forming all sorts of typical and atypical/unexpected associations with hosts. Among Parasitiformes, apart from the Opilioacarida and Holothyrida as free-living mites and the Ixodida as specialized parasites of various vertebrates, the Mesostigmata is the only order of the superorder with some lineages as invertebrate parasites. All known hosts are arthropods, mostly insects. Among Acariformes, the cohort (or hyporder) Astigmatina (Sarcoptiformes: Oribatida) includes some parasites of invertebrates, including a few non-aquatic insects. The most biologically diverse group in Acariformes is the Prostigmata, one of the two suborders in the order Trombidiformes, which encompasses many lineages that have evolved parasitic relationships with invertebrates. Larvae (and sometimes postlarval instars) of the cohort (or hyporder) Parasitengonina (both terrestrial and aquatic) parasitize a wide spectrum of invertebrates, including arthropods and non-arthropods, such as mussels and snails. Some genera of marine and freshwater mites of the superfamily Halacaroidea (in the supercohort or infraorder Eupodides) are known or suspected parasites of gastropods, decapod crustaceans, nemerteans, sponge echinoids, deep-sea urchins, chitons and crayfishes. Rohde (2005) mentioned that almost all parasitic mites of marine invertebrates are members of the family Halacaridae. Although most members of the parasitic family Pterygosomatidae are associated with reptiles and tortoises, those of the genus Pimeliaphilus can be found on arthropods, such as scorpions, cockroaches, beetles and reduviid bugs. A few representatives of the family Ereynetidae (Eupodides) attack slugs and snails. There are several lineages in the cohort Heterostigmatina known either as parasites (Heterocheylidae, Crotalomorphidae, Podapolipidae and some Tarsonemidae) or parasitoids (Pyemotidae, Acarophenacidae and tarsonemid genus Iponemus) sensuLindquist (1983). The hosts are insects, mostly coleopterans, none of them aquatic (Kaliszewski, Athias-Binche & Lindquist, 1995; Krantz, 2009; Walter et al., 2009; Walter & Proctor, 2013). So far, no taxon of mites (including Mesostigmata and Astigmatina) parasitic in all active instars has been recovered from any group of water beetles, including Dytiscidae. Among insects of various orders, adult beetles of the order Coleoptera are the most frequently and abundantly parasitized. Different beetle families are exploited by parasitic mites, e.g. Carabidae, Scarabaeidae, Tenebrionidae, Curculionidae (including Scolytinae), Passalidae, Silphidae, Dermestidae and Buprestidae (Walter et al., 2009; Walter & Proctor, 2013). However, relatively few mites have evolved symbiotic relationships with groups of water beetles. Only three genera of mites, all only as larvae, belonging to the water mite subcohort (or hyporder) Hydrachnidiae (Trombidiformes: Prostigmata: Parasitengonina) are recorded as parasites of water beetles: Hydrachna Muller, 1776 (Hydrachnoidea: Hydrachnidae), Eylais Latreille, 1796 (Eylaoidea: Eylaidae) and Acherontacarus Angelier, 1951 (Hydrovolzioidea: Acherontacaridae) (Zawal, 2002; Aykut, Esen & Taşar, 2016; Aykut & Esen, 2017). Larvae of Acherontacarus are attached to the mesosternal regions of their host dytiscid beetles, Scarodytes halensis (Fabricius, 1787) and seven species of the genus Agabus. Larvae of the genera Hydrachna and Eylais, however, settle mostly under host elytra. Those of Hydrachna parasitize water beetles (Dytiscidae, Hydrophilidae), chiefly in astatic waters. They are better known as parasites of aquatic hemipterans (Zawal, 2002). Among dytiscids, beetles mostly of the genera Dytiscus and Acilius, and to lesser extent of Graphoderus, Ilybius, Rhontus, Coelambus and Hydaticus, are parasitized by larval mites of the genus Hydrachna (Zawal, 2002). In a continuation of studies on mites associated with insects in southern Iran, a colony of all instars of parasitic mites representing an undescribed family-group taxon were found on a dytiscid beetle. In an independent study about four decades ago, one of us (E.E.L.) became aware of two different species of the same taxon from Florida, USA. The objectives of this paper are to report the discovery of this new group as a family of raphignathine mites, highly specialized as parasites of adult dytiscid beetles, based on a new genus and three new species from Iran and the USA, to describe its structural characteristics, and to argue for its placement in the cohort (or hyporder) Raphignathina. Finally, we review and discuss invertebrate parasitism in the supercohort (or infraorder) Eleutherengonides. MATERIAL AND METHODS The dytiscid host beetles were captured by attracting them to light traps near lagoons or swamps. In Hormozgan province, southern Iran, four host specimens were obtained, among which one was infested by a large colony of parasitic mites under its elytra. In Florida, USA, some 19 beetle hosts were found to harbour similar subelytral parasitic mites. Mite specimens were removed from the beetles, sometimes cleared in a mixture of lactophenol and Nesbitt’s solution before being mounted in Hoyer’s or polyvinyl alcohol medium on microslides. Morphological observations, measurements and illustrations were made using compound light microscopes (Olympus BX51, Tokyo, Japan, and Reichert Zetopan, Vienna, Austria) using × 1000–2000 (oil immersion) magnification and either phase contrast or differential interference contrast (DIC) optical systems. All measurements in the descriptions are given in micrometres for the holotype and up to five paratypes (in parentheses, if available). Unless stated otherwise, setae are tapered, smooth and pointed apically. Setae that are no longer than the diameters of setal alveoli are listed as mentum (m), and setae with only alveoli and no remnants of setae are listed as ventral setae (v). The morphological terminology is based on Grandjean (1935, 1939, 1943), Lindquist (1986), Evans (1992), Alberti & Coons (1999) and Bochkov, OConnor & Wauthy (2008), with setal notation italicized in text and figures. The system of mite classification follows Lindquist, Krantz & Walter (2009), with alternative names for higher categories used by Zhang et al. (2011) given parenthetically. RESULTS Morphological observations Some preliminary observations on particular morphological aspects of the new mites are presented here, for perspectives before the descriptions of these taxa. Gnathosoma (Figs 1, 2) Dorsally, the proximal half of the gnathosoma is covered by a thin roof, or ‘tegulum’, sensuAlberti & Coons (1999), Evans (1992) that seems to form from extensions of the lateral walls of the palp coxisternal bases. Its lateral margins are continuous with bands of soft cuticle arising from the dorsal face of the palpcoxae (Figs 1, 2A). As its base is continuous with that of the infracapitulum and enveloped by a collar of soft cuticle of the prosoma, it is not a hood-like extension of the prodorsum, as seen among, e.g. penthalodid or cryptognathid mites. Although it might be a remnant of a stylophore formed from the cheliceral bases, there is no discernible connection between it and the cheliceral sheaths that envelop the cheliceral stylets and are deeply retractable into the proterosoma. At a visual plane immediately ventral to the anterior margin of the tegulum, a pair of prominent stigmata, the ‘neostigmata’, open via a very short pair of vertical tracheal trunks from a pair of long, main tracheal trunks, on a slightly yet more ventral plane, that extend proximally and originate from the basal area in which the intercheliceral stigmata (‘prostigmata’ sensuAlberti & Coons, 1999) are located. The main tracheal trunks lie so closely dorsal to the long, slender cheliceral stylets that it is difficult to confirm visually whether they are free from the cheliceral sheaths, which continue more proximally around the stylet bases. The exact location of the prostigmata, whether above, between or below the stylets, is uncertain. Figure 1. View largeDownload slide Dytiscacarus americanus sp. nov. (female). A, gnathosoma, dorsal aspect, showing respiratory and adjacent podocephalic systems. B, gnathosoma, ventral aspect, showing cheliceral and subcapitular details (stylets fully outlined/exposed). Abbreviations: nst, neostigmata; pc, podocephalic canal; ph, pharynx; sh, sheath; st, stylet; stg, stigma; tg, tegulum; tr, trachea. Figure 1. View largeDownload slide Dytiscacarus americanus sp. nov. (female). A, gnathosoma, dorsal aspect, showing respiratory and adjacent podocephalic systems. B, gnathosoma, ventral aspect, showing cheliceral and subcapitular details (stylets fully outlined/exposed). Abbreviations: nst, neostigmata; pc, podocephalic canal; ph, pharynx; sh, sheath; st, stylet; stg, stigma; tg, tegulum; tr, trachea. Figure 2. View largeDownload slide Dytiscacarus americanus sp. nov. (female). A, near midline schematic longitudinal section of gnathosoma (dorsoventral dashed line indicates approximate plane of transverse section). B, virtual transverse section through subapical part of gnathosoma (dotted ventral structures at more apical planes). Abbreviations: ad, adoral setae; g, groove, dorsal face infracapitulum; m, subcapitular seta; ns, neostigmata; oe, oesophagus; pc, palp coxal bases; ph, pharynx; pr, ‘prostigmata’ (area of intercheliceral stigmata); sh, sheath; st, stylet; st l, stylet lever; tg, tegulum; tr, trachea. Figure 2. View largeDownload slide Dytiscacarus americanus sp. nov. (female). A, near midline schematic longitudinal section of gnathosoma (dorsoventral dashed line indicates approximate plane of transverse section). B, virtual transverse section through subapical part of gnathosoma (dotted ventral structures at more apical planes). Abbreviations: ad, adoral setae; g, groove, dorsal face infracapitulum; m, subcapitular seta; ns, neostigmata; oe, oesophagus; pc, palp coxal bases; ph, pharynx; pr, ‘prostigmata’ (area of intercheliceral stigmata); sh, sheath; st, stylet; st l, stylet lever; tg, tegulum; tr, trachea. The stylets are located and move along a groove or gutter on the dorsal surface of the infracapitulum (the ‘subcheliceral plate’, sensuEvans, 1992). The stylet apices project between the anteromedial margins of the infracapitulum in an area dorsal and proximal to the most apical infracapitular lobes (Fig. 2A). That area is slightly above the plane of the mouth, which leads to a strongly formed, muscular pharynx, immediately under the stylets. Amidst material at hand, it is unclear how extensible are such long, slender but strongly sclerotized stylets; yet the reality of such stylet length and deep sheathing indicates extensive projection. Although the stylets are closely aligned in parallel along the distal halves of their length, they do not seem to function together as a single tube (e.g. as in Tetranychoidea), apically. Their apices remain slightly separate, and each stylet seems capable of independent projection, in view of their asymmetrical degrees of retraction in some preparations of the mites (for example, in a female of one species, one stylet with total length of ~90 μm is extruded for ~60 μm of its length, whereas the other is fully retracted). The bases of the stylets are linked to rather short, weakly formed cheliceral levers. Available specimens are so macerated that musculature of the levers is indiscernible; however, it is difficult to envision such elongated muscles originating from the tegulum and extending to those short levers; such complete sheathing might indicate that idiosomatic hydrostatic pressure is involved in stylet protraction. The ventral face of the infracapitulum is simple in form as a mentum, without subdivisions other than a short medial one between its anterior lobes. It bears one pair of prominent infracapitular setae, m, inserted in an anterior, rather than median, position. The anterior lobes bear tiny, blunt remnants of two pairs of adoral setae, ad1, 2, which are more evident, ontogenetically, in the larval instar. The freely projecting, three-segmented palpi consist of a glabrous trochanter, a femorogenu with two setae representing different segmental verticils (femoral d and genual d), and a tibiotarsus with four setae, notably lacking a solenidion and without any remnant of a thumb-claw process. Of the four palp tibiotarsal setae, only the largest, strongly arcuate one appears eupathidial (perhaps the homologue of acm, according to the terminology of Grandjean, 1935). The supracoxal seta is absent near the base of the palpus on each side of the infracapitulum. Male genital capsule (Fig. 3A) The male genitalia are housed in a genital capsule that is more strongly developed than in any other known taxon in Raphignathina, and otherwise found only among the more derivative families of Heterostigmata. The structures of somites H and PS are formed into a sclerotized capsule, within which there is a large, sclerotized, arcuate, apparently protrusible aedeagus, flanked by a pair of prominent processes, each with two tiny, evidently setigenous (i.e. optically birefringent) apices. Superficially, this structural complex may be argued for placement of the new taxon in the Heterostigmata. However, arguments against that placement are presented in the section on systematics, below. Furthermore, some of the key structures composing the male genitalia of the new taxon have putatively different homologous origins. As all setae of somite H (h1–h3) and one pair of setae of somite PS (ps1?) of the female are accounted for on external surfaces of the male genital capsule, we hypothesize that those tiny setigenous apical structures on the pair of processes flanking the aedeagus of the new taxon are ps2 and ps3. In contrast, the accessory genitalic structures in the genital capsule of various heterostigmatic taxa (Trochometridiidae, Pyemotidae, Acarophenacidae and Tarsonemidae) are ps1 and ps2, which persist as separate structures in differently modified form (see figs 14–18 of Lindquist, 1986). Apart from these putative differences in setal homologues, their differently modified forms suggest independent origins of male genital capsules between the new taxon and heterostigmatans. However, comparative studies of male genital structures among families of Raphignathina have yet to be done. Leg tarsal structures (Fig. 3B–E) All active instars of the new taxon have well-developed legs, with tarsi bearing strongly sclerotized claws of uniquely modified form, evidently for hooking and grasping. The peculiar form is similar on all legs of all instars. The bases of the claw shafts are deeply embedded into nearly half the tarsal length, where they are connected to a sclerotized framework for musculature attachment. Subproximally, where it emerges from the tarsus, each shaft has a multibranched limb, with one clearly formed, ventral barb. Each of the dorso-apical pair of proral setae is peculiarly bent laterally at a right angle, so its apex apposes the processes of the shaft branch at that level (Fig. 3B, C). The main shaft continues, nearly straight and untapered, until its apex, where it becomes elaborated into a widened, flexible, saucer- and comb-like structure, seemingly for adhesion. Somewhat comparable claw modifications are evident among some members of the aquatic mite superfamily Halacaroidea, whose claws may have a basal hook and distal comb-like expansions (Walter et al., 2009). However, with its well-developed prostigmatic respiratory system and suite of modified gnathosomatic structures, the new taxon is not phylogenetically related to that aquatic group in the supercohort (or infraorder) Eupodides (see section on classification, below). Among eleutherengone mites, there are none with remotely similar claw structures designed for exceptional grasping and adhesion, which begs the hypothesis of a chronologically deep association with these mites and their dytiscid beetle hosts. Figure 3. View largeDownload slide Dytiscacarus americanus sp. nov. A, male genital capsule, dorsal aspect. B, pretarsus and tarsus I, female, dorsal aspect. C, twisted pretarsal and tarsal II structures, female, ventral aspect. D, pretarsus I of larva, ventral aspect. E, pretarsus II of larva, ventral aspect. Figure 3. View largeDownload slide Dytiscacarus americanus sp. nov. A, male genital capsule, dorsal aspect. B, pretarsus and tarsus I, female, dorsal aspect. C, twisted pretarsal and tarsal II structures, female, ventral aspect. D, pretarsus I of larva, ventral aspect. E, pretarsus II of larva, ventral aspect. SYSTEMATICS Dytiscacaridae Hajiqanbar and Lindquist fam. nov. Type genus Dytiscacarus Hajiqanbar and Lindquist gen. nov. Diagnosis There are four postembryonic instars (larva, protonymph, deutonymph and adult) characterized by the following combination of characters: gnathosoma without dorsal setae, but with one pair of ventral setae m in rostral area; palps moderately well developed, projecting anteromedially, freely from apices of infracapitulum, with three segments (trochanter, femorogenu and tibiotarsus), lacking a thumb-claw process; trochanter nude, femorogenu with two setae (dFe and dGe), tibiotarsus with four setae (acm, sul, ul’ and ul”), seta ul’ characteristically strongly curved; cheliceral bases reduced, with a remnant covering basal dorsum of infracapitulum, and with sheaths deeply embedded and hardly visible encasing long, slender stylets fully retractable into proterosoma; infracapitulum with pharynx muscular, entire, fusiform; paired intercheliceral stigmata located centrally within gnathosoma, with a pair of tracheal trunks leading to neostigmata opening on dorsal infracapitular surface, and with another pair of tracheal trunks extending posteriorly into anterior region of proterosoma. Idiosoma with a series of fragmented tergites separated by striated soft integument in immature instars, which become largely amalgamated in adults; podocephalic canals present anterolaterally on prosoma, above bases of legs I; prodorsum lacking eyes and trichobothria, and not delineated from opisthosoma by a dorsosejugal furrow; idiosomatic setae short, smooth, without neotrichy; all instars with prodorsal sclerotization integrated to some extent with that of opisthosomatic tergite C, such that prodorsal setae sce are together with tergital setae c1, c2 on same plate(s); four pairs of prodorsal setae (vi, ve, sci and sce); dorsal opisthosomatic setal complement with c1, c2, d, e, f1, f2, h1, h2, h3, ps1, ps2 and ps3; cupules absent. Opisthosomatic venter, with anterior and posterior epimera articulating with bases of legs I–II and III–IV, respectively; legs II and III well separated by soft cuticle; extension of opisthosoma markedly abbreviated behind metapodosoma, such that legs III–IV are located near posterior extremity of body. Adult female genital aperture a longitudinal fissure between bases of legs IV, nearly contiguous posteriorly with caudal anus, without genital papillae and genital setae (g series); anal region with three pairs of setae, including ad1 on anal valves, flanked by ps1 and ps2 on soft integument. Adult male with fully formed terminal genital capsule, bearing tiny setae h1, h2, h3 and ps1 on external surfaces; aedeagus well sclerotized, flanked by a pair of accessory processes, with divided birefringent setigenous apices (ps2 and ps3). All instars with all legs each having five segments, similar to one another in size, structure and form of setae, except adult female with legs IV longer than other legs; tarsi I–IV lacking empodium elements, and with paired claws deeply rooted in tarsi and symmetrically modified into well-sclerotized tenent structures; tarsi I and II each with one solenidion; solenidia absent on other leg segments, and eupathidium k absent on tibia I; leg setation reduced from complement present among free-living raphignathines (see genus description). Dytiscacarus Hajiqanbar & Lindquist gen. nov. (Figs 1–49) Type species Dytiscacarus iranicus sp. nov. Mortazavi and Hajiqanbar. Diagnosis As for family (monobasic). In addition, see the following descriptions. Adult female Body fusiform, flattened, shorter dorsoventrally than wide laterally. Surface of dorsal idiosoma mostly covered by coalesced tergite (Prs + C + D + E); tergite F entire; tergite H subquadrate. Ventrally, anterior and posterior epimera not fused, carrying five and three pairs of setae, respectively (setae 3a off posterior epimera). Leg setae smooth except (p) and (u); tarsi I–IV with setae (p) abruptly bent laterad along mid-length, finely pectinate in ventral aspect; setae (pv) originate from a joint alveolus or contiguous alveoli; tarsus I with blunt-ended setae (tc), (u) and (a); setae (a) and (u) on pinnacula, and (u) finely pectinate. Leg setation, trochanter, femur, genu, tibia and tarsus, respectively, as follows. Leg I: 1 (v), 4 (d, l’, l”, v”), 4 (d, l’, l”, v’), 5 (d, l’, l”, v’, v”), 12 (+1) (a’, a”, tc’, tc”, u’, u”, p’, p”, ft’, ft”, pv’, pv”, +ω). Leg II: 1 (v), 4 (d, l’, l”, v”), 2 (d, v’), 5 (d, l’, l”, v’, v”), 8 (+1) (tc’, tc”, u’, u”, p’, p”, pv’, pv”, +ω). Leg III: 1 (v), 1 (d), 1 (v’), 5 (d, l’, l”, v’, v”), 8 (tc’, tc”, u’, u”, p’, p”, pv’, pv”). Leg IV: 1 (v), 1 (d), 1 (v’), 5 (d, l’, l”, v’, v”), 8 (tc’, tc”, u’, u”, p’, p”, pv’, pv”). Male As in adult female except tergite F fragmented to two pairs of platelets, inner pair with setae f1 and outer pair with setae f2; tergite H incorporated into terminal genital capsule bearing tiny setae h1–h3 dorsolaterally and ps1 caudally, and containing a long sclerotized aedeagus, one pair of claspers, each ending with a pair of setigenous bifid processes (ps2, ps3). Tarsi I–IV with setae (u) and (p) smooth, not discernibly pectinate; setae (pv) with separate, adjacent alveoli. Tibia I d microseta. Deutonymph As in adult female except dorsal idiosoma with six plates; mid-section of prodorsal shield situated between divided plates bearing setae sce, c1 and c2; other tergites each entire (DE with d and e; F with f1 and f2; H with h1–h3); rudiments of four or five pairs of pseudanal and adanal setae on soft plicated cuticle flanking anal opening. Tarsi I–IV with setae (u) and (p) smooth, not pectinate; setae (pv) with separate alveoli. Protonymph As in deutonymph except tergites F and H divided medially. Pseudanal and adanal setae absent on soft cuticle flanking anal opening. Genu IV nude. Larva As in deutonymph except tergite DE divided medially and tergite H absent, but with rudiments of setae h1–h3 evident on soft caudal cuticle; pseudanal setae absent. Epimera with two pairs of setae on plates I, no seta on plates II and one pair on plates III. Anal opening present. Leg setation as follows. Leg I: 0, 4 (d, l’, l”, v”), 2 (l’, l”), 5 (d, l’, l”, v’, v”), 10 (+1) (tc’, tc”, u’, u”, p’, p”, ft’, ft”, pv’, pv”, +ω). Leg II: 0, 2 (d, v”), 0, 5 (d, l’, l”, v’, v”), 8 (+1) (tc’, tc”, u’, u”, p’, p”, pv’, pv”, +ω). Leg III: 0, 1 (d), 0, 5 (d, l’, l”, v’, v”), 8 (tc’, tc”, u’, u”, p’, p”, pv’, pv”). Tarsus I with setae (tc) eupathidial. Etymology The generic name is a combination of the Greek dytisc-, meaning diving, in reference to the family of diving beetles Dytiscidae, and the Latinized acarus of the Greek akari for mite. The family-group host name is chosen, anticipating that beetles of diverse genera (other than only Hydaticus and Thermonectus) may be hosts to these mites. Included taxa This genus currently includes three species. Dytiscacarus iranicus Mortazavi and Hajiqanbar sp. nov. (Figs 4–18) Description Adult female (Figs 4–6) Milky white colour when alive. Gnathosoma (Figs 4B, 5B): Length of gnathosoma 59 (50–62), width 61 (53–66). Length of stylets 111 (103–105); pharynx 34 (29–30) long and 15 (14–15) wide; infracapitulum with setae m 11 (15–17), interval between their bases 8 (9–12). Palpi 19 (21–22) long, femorogenu with setae dGe 13 (11–14), more than twice as long as blunt dFe 5 (3–5); tibiotarsus with seta sul 4 (4–5) blunt, shorter than blunt acm 8 (7–9); seta ul’ 12 (9–11) characteristically bent, longer than blunt ul” 7 (6–8). Figure 4. View largeDownload slide Dytiscacarus iranicus sp. nov. (female). A, dorsal habitus, without leg setation. B, gnathosoma, dorsal view. Figure 4. View largeDownload slide Dytiscacarus iranicus sp. nov. (female). A, dorsal habitus, without leg setation. B, gnathosoma, dorsal view. Figure 5. View largeDownload slide Dytiscacarus iranicus sp. nov. (female). A, ventral habitus, without leg setation. B, gnathosoma, ventral view. Figure 5. View largeDownload slide Dytiscacarus iranicus sp. nov. (female). A, ventral habitus, without leg setation. B, gnathosoma, ventral view. Idiosoma: Length of idiosoma 445 (613), width 380 (388). Idiosomatic dorsum (Fig. 4A) with length of plate PrsCDE 340 (325–335), width 355 (338–358), with microsetae vi, d, e (d in one of paratypes larger, 3 long), ve shorter than other PrsCDE setae, sci, c1, c2 subequal. Tergite F 25 (30–38) long and 90 (100–113) wide, approximately three times wider than long, with two pairs of microsetae. Tergite H 63 (63–63) long and 85 (88–100) wide, subquadrate, with three pairs of microsetae, interval between h3 bases greater than that between h2 bases. All dorsal plates with tiny dimples. Lengths of setae: ve 10 (10–10), sci 16 (13–14), sce 13 (10–15), c1 16 (15–15), c2 16 (15–16); intervals between setae: vi–vi 22 (22–30), ve–ve 94 (94–101), sci–sci 76 (67–76), vi–ve 48 (39–45), vi–sci 103 (86–89), sci–ve 69 (69-69), sce–sce 263 (250–288), c1–c1 130 (135–148), c2–c2 313 (298–300), c1–sce 100 (95–98), c1–c2 90 (80–110), c2–sce 70 (70–80), d–d 42 (39–45), e–e 134 (140–145), d–e 47 (50–51), f1–f1 28 (31–36), f2–f2 76 (80–83), f1–f2 27 (27–30), h1–h1 41 (42–47), h2–h2 48 (47–48), h3–h3 64 (56–72), h1–h2 14 (17-17), h1–h3 19 (17–28), h2–h3 9 (9–14). Idiosomatic venter (Fig. 5A): apodemes 1 (ap1) well developed, not connecting with slightly shorter apodemes 2; sejugal apodeme weakly developed laterally; apodemes 3 and 4 well developed but not connected medially; coxal fields 1–4 with tiny dimples and needle-like setae. Anal region with setae ad1, ps3 tiny, blunt, setae ps1, ps2 distinctly stouter than ad1 and ps3, both stiff, blunt. Lengths of setae: 1a 17 (16–17), 1b 15 (13–14), 1c 15 (10–15), 2a 16 (15–15), 2b 17 (16–17), 3a 15 (11–14), 3b 22 (19–20), 3c 16 (19–21), 4a 19 (16–19), ps1 7 (5–9), ps2 6 (5–7), ad1 3 (3–3) and ps3 4 (4–6); intervals between setae: 1a–1b 47 (41–48), 1b–1c 47 (47–47), 1a–1c 39 (23–41), 1a–2a 51 (48–50), 2a–2b 23 (23–28), 3a–3a not measurable in holotype owing to torn integument (47–56), 3b–3c 34 (33–34), 3c–4a 58 (62–67), 3b–4a 78 (78–90) and ps1–ps2 6 (5–6). Legs (Fig. 6): Legs I and II shorter than other legs, with leg IV longest. Lengths of leg segments are as follows: leg I: Tr 31 (28–39), Fe 55 (47–53), Ge 23 (22–23), Ti 23 (23–27), Ta 41 (36–41); leg II: Tr 31 (27–31), Fe 51 (47–48), Ge 23 (22–23), Ti 23 (23–25), Ta 39 (39–41); leg III: Tr 44 (33–44), Fe 55 (55–62), Ge 22 (23–27), Ti 25 (23–27), Ta 58 (45–51); and leg IV: Tr 44 (39-39), Fe 73 (70–75), Ge 30 (27–28), Ti 31 (28–33), Ta 58 (55-55). Figure 6. View largeDownload slide Dytiscacarus iranicus sp. nov. (female). Dorsal aspects of legs I–IV, with separate ventral aspects of tarsi. A, leg I. B, leg II. C, leg III. D, leg IV. Figure 6. View largeDownload slide Dytiscacarus iranicus sp. nov. (female). Dorsal aspects of legs I–IV, with separate ventral aspects of tarsi. A, leg I. B, leg II. C, leg III. D, leg IV. Leg I 148 (145–156) (Fig. 6A): Tarsus: setae (ft) thin, ft” 4 (3–3) coupled with solenidion ω and shorter than ft’ 7 (6–8), tc’ 19 (15–19) and tc” 16 (16–16) longer than other tarsal setae, solenidion ω 15 (12–16) baculiform; tibia: seta v’ 15 (15–19), longer than l’, l” and v” 9 (9–9), seta d 78 (73–82) whip like, attenuated, longer than other leg setae; genu: d 19 (19–24) and v’ 19 (19–24) longer than other genual setae, l’ and l” subequal; femur: d 49 (60–79) attenuated, longer than other femoral setae, v” 39 (31–34) attenuated, longer than setae l’ and l”; trochanter: seta v 23 (22–24) shorter than length of segment. Leg II 140 (133–148) (Fig. 6B): Tarsus: setae tc’ 19 (21–22) and tc” 21 (19–24) subequal, attenuated, longer than setae (pv), solenidion ω 19 (16–20) baculiform, longer than tarsus I solenidion; tibia: setae v’ 16 (11–15) and v” 13 (10–19) subequal, shorter than attenuated, whip-like seta d 58 (63–73), longer than other leg setae; genu: d 17 (15–17) shorter than v’ 18 (19–22); femur: d 53 (49–58) attenuated, longer than other femoral setae, seta v” 24 (29–37) attenuated, longer than l’ and l”, seta l’ longer than l”; and trochanter: seta v 29 (22–26) longer than length of segment (in paratypes shorter than length of segment). Leg III 187 (164–179) (Fig. 6C): Tarsus: setae tc’ 29 (24–24) and tc” 29 (24–32) subequal, attenuated, longer than setae (pv); tibia: setae v’ 15 (15–15) and v” 15 (15–19) subequal, shorter than attenuated, whip-like seta d 87 (87–92), longer than other leg setae; genu: v’ 17 (15–18) shorter than length of segment; femur: d 18 (17–19) as long as genual seta v’; and trochanter: seta v 24 (19–21) shorter than length of segment. Leg IV 223 (215–218) (Fig. 6D): Tarsus: setae tc’ 31 (34–36) and tc” 38 (27–39) attenuated, longer than setae (pv); tibia: setae v’ 17 (19–19) and v” 18 (11–15) shorter than attenuated, whip-like seta d 121 (121–126), which is longest of all leg setae; genu: seta v’ 10 (10) shorter than length of segment (absent in some specimens); femur: seta d 16 (14–15) as long as tibial seta v”; trochanter: seta v 26 (19–19) shorter than length of segment. Male (Figs 7–9) Milky white colour when alive and shorter than adult female. Gnathosoma (Figs 7B, 8B): Length of gnathosoma 47 (53), width 44 (48). Length of stylets 92 (85); pharynx length 24 (24) and width 11 (11); infracapitulum with setae m 15 (10), interval between their bases 7 (8). Palpi 16 (17), femorogenu with setae dGe 8 (10), longer than blunt dFe 4 (6); tibiotarsus with seta sul 4 (5) blunt, shorter than blunt acm 6 (6), seta ul’ 10 (9) characteristically bent, longer than blunt ul” 7 (5). Figure 7. View largeDownload slide Dytiscacarus iranicus sp. nov. (male). A, dorsal habitus, without leg setation. B, gnathosoma, dorsal view. Figure 7. View largeDownload slide Dytiscacarus iranicus sp. nov. (male). A, dorsal habitus, without leg setation. B, gnathosoma, dorsal view. Figure 8. View largeDownload slide Dytiscacarus iranicus sp. nov. (male). A, ventral habitus, without leg setation. B, gnathosoma, ventral view. Figure 8. View largeDownload slide Dytiscacarus iranicus sp. nov. (male). A, ventral habitus, without leg setation. B, gnathosoma, ventral view. Idiosoma: Length of idiosoma 400 (–), width 315 (–) (in paratype broken and not measurable). Idiosomatic dorsum (Fig. 7A) with length of plate PrsCD 258 (250), width 278 (275), with microsetae vi, d; e shorter than other PrsCDE setae, sci, c1 and c2 subequal; posterior margin of plate PrsCD entire, not incised, with soft cuticle medially between setae d. Outer platelets F 6 (3) long and 6 (6) wide, round, weakly sclerotized, each with one microseta; inner platelets F 8 (8) long and 14 (14) wide, ellipsoid, weakly sclerotized, each with one microseta. Genital capsule 64 (62) long and 76 (81) wide, subquadrate, with four pairs of microsetae, interval between ps1 bases shorter than that between h1 bases; length of aedeagus 94 (92), length of claspers 47 (39). All dorsal plates and genital capsule with tiny dimples. Lengths of setae: ve 12 (15), sci 16 (17), sce 16 (15), c1 16 (16), c2 15 (11), d2 5 (5); intervals between setae: vi–vi 16 (23), ve–ve 80 (83), sci–sci 69 (62), vi–ve 34 (34), vi–sci 70 (67), sci–ve 48 (45), sce–sce 193 (178), c1–c1 105 (108), c2–c2 211 (206), c1–sce 67 (66), c1–c2 51 (50), c2–sce 44 (45), d–d 41 (47), e–e 148 (134), d–e 53 (50), h1–h1 43 (41), h2–h2 49 (53), h3–h3 54 (63), h1–h2 6 (10), h1–h3 16 (15), h2–h3 10 (7), ps1–ps1 37 (47), h3–ps1 22 (15). Idiosomatic venter (Fig. 8A): apodemes 1 (ap1) well developed, not reaching to slightly longer apodemes 2; sejugal apodeme weakly developed laterally; apodemes 3 and 4 well developed but not connected medially; coxal fields 1–4 with tiny dimples, all ventral setae stiff, needle like, except 1c (microseta). Lengths of setae: 1a 10 (10), 1b 11 (10), 2a 9 (7), 2b 5 (4), 3a 7 (9), 3b 11 (10), 3c 4 (3), 4a 7 (7); intervals between setae: 1a–1b 39 (37), 1b–1c 39 (39), 1a–1c 34 (32), 1a–2a 44 (45), 2a–2b 20 (22), 3a–3a 37 (41), 3b–3c 31 (31), 3c–4a 53 (53) and 3b–4a 72 (72). Legs (Fig. 9): Legs I thicker than others; all legs subequal in length. Length of leg segments is as follows: leg I: Tr 31 (36), Fe 39 (39), Ge 16 (16), Ti 16 (16), Ta 22 (23); leg II: Tr 31 (36), Fe 39 (41), Ge 14 (16), Ti 16 (20), Ta 23 (22); leg III: Tr 36 (47), Fe 42 (39), Ge 14 (16), Ti 16 (19), Ta 23 (25); and leg IV: Tr 44 (47), Fe 41 (45), Ge 14 (16), Ti 16 (16), Ta 23 (27). Figure 9. View largeDownload slide Dytiscacarus iranicus sp. nov. (male). Dorsal aspects of legs I–IV, with separate ventral aspect of tarsus I. A, leg I. B, leg II. C, leg III. D, leg IV. Figure 9. View largeDownload slide Dytiscacarus iranicus sp. nov. (male). Dorsal aspects of legs I–IV, with separate ventral aspect of tarsus I. A, leg I. B, leg II. C, leg III. D, leg IV. Leg I 100 (115) (Fig. 9A): Tarsus: setae tc’ 17 (19) and tc”, 19 (18) stiff, blunt, setae (ft) microsetae, (u) and (p) blunt; ft” very close to baculiform solenidion ω 15 (14), setae (a) subequal, and blunt, interval between (pv) bases 9 (8); tibia: seta v’ 7 (7) blunt, longer than blunt l’ and v” 4 (5), setae l” and d microsetae; genu: d, l’ and l” microsetae, seta v’ 4 (4) stiff, blunt; femur: d 18 (20) longer than other femoral setae, v” 5 (6) blunt, longer than blunt setae l’ and l”; and trochanter: seta v 4 (3) tiny, blunt. Leg II 94 (98) (Fig. 9B): Tarsus: setae tc’ 19 (19) and tc” 19 (15) subequal, attenuated, slightly longer than setae (pv), setae (u) and (p) blunt, solenidion ω 23 (20) baculiform, longer than tarsus I solenidion, interval between bases of setae (pv) 8 (8) greater than length of seta v” on tibia; tibia: seta v’ 8 (7) longer than seta v” 4 (5), both blunt, shorter than attenuated, whip-like seta d 55 (44), setae (l) minute; genu: seta d microseta, seta v’ 6 (5) stiff, blunt; femur: seta d 28 (24), shorter than segment, v” 13 (15) blunt, longer than small, blunt (l); and trochanter: blunt seta v small 4 (7). Leg III 94 (117) (Fig. 9C): Tarsus: setae tc’ 17 (19) shorter than tc” 19 (24), both attenuated, longer than setae (pv), setae (u) and (p) blunt, smooth, interval between bases of setae (pv) 8 (7) greater than length of seta v’ on genu; tibia: setae (v) subequal, 7 (7, 8) blunt, stiff, shorter than attenuated, whip-like seta d 55 (53), setae (l) minute; genu: seta v’ 6 (5) blunt; femur: seta d 10 (10) blunt, longer than seta v’ on genu; and trochanter: seta v 6 (5) blunt, stiff. Leg IV 117 (117) (Fig. 9D):Tarsus: setae tc’ 21 (23) and tc” 24 (24) attenuated, longer than setae (pv), setae (u) and (p) blunt, interval between bases of setae (pv) 8 (7) greater than length of seta v’ on genu; tibia: setae (v) subequal, 10 (10, 11) blunt, stiff, shorter than attenuated whip-like seta d 63 (63), the longest of all leg setae, setae (l) minute; genu: seta v’ 4 (3) blunt, stiff; femur: seta d 6 (6) blunt, longer than seta v’ on genu; and trochanter: blunt seta v 7 (5) longer than v on Tr III. Deutonymph (Figs 10–12) Milky white colour when alive. Gnathosoma (Figs 10B, 11B): Length of gnathosoma 68 (60–75), width 66 (61–72); stylets 105 (107–113) long; pharynx 32 (29–34) long and 15 (13–15) wide; infracapitulum with setae m 15 (14–16), interval between their bases 10 (10–14). Palpi 20 (19–22), femorogenu with setae dGe 10 (9–11) about twice as long as blunt dFe 5 (5–7); tibiotarsus with seta sul 5 (5–6) blunt, shorter than blunt acm 6 (7–8), seta ul’ 11 (10–11) characteristically bent, longer than blunt seta ul” 8 (6–8). Figure 10. View largeDownload slide Dytiscacarus iranicus sp. nov. (deutonymph). A, dorsal habitus, without leg setation. B, gnathosoma, dorsal view. Figure 10. View largeDownload slide Dytiscacarus iranicus sp. nov. (deutonymph). A, dorsal habitus, without leg setation. B, gnathosoma, dorsal view. Figure 11. View largeDownload slide Dytiscacarus iranicus sp. nov. (deutonymph). A, ventral habitus, without leg setation. B, gnathosoma, ventral view. Figure 11. View largeDownload slide Dytiscacarus iranicus sp. nov. (deutonymph). A, ventral habitus, without leg setation. B, gnathosoma, ventral view. Idiosoma: Length of idiosoma 605 (495–625), width 475 (475–488). Idiosomatic dorsum (Fig. 10A): PrsC with central plate 290 (283–300) long, 185 (165–178) wide, club shaped, with vi microsetae, setae ve and sci subequal; each lateral plate 193 (175–190) long and 155 (138–150) wide, kidney shaped, seta sce shorter than subequal c1 and c2. Tergite DE 100 (75–83) long and 275 (270–285) wide, ellipsoid with two pairs of microsetae, (e in one of paratypes longer, 3). Tergite F 58 (45–50) long and 188 (185–193) wide, ellipsoid, thinner than other tergites, with two pairs of microsetae. Tergite H 88 (68–88) long and 188 (110–185) wide, ellipsoid, with three pairs of microsetae, interval between h1 shorter than that between h2. All dorsal plates with tiny dimples. Lengths of setae: ve 15 (13–15), sci 19 (15–19), sce 16 (15–17), c1 19 (15–21), c2 19 (16–19); intervals between setae: vi–vi 41 (20–45), ve–ve 115 (109–117), sci–sci 78 (70–80), vi–ve 62 (51–59), vi–sci 112 (100–109), sci–ve 67 (64–70), c1–sce 109 (101–106), c1–c2 94 (87–92), c2–sce 75 (70–75), d–d 73 (51–100), e–e 209 (203–212), d–e 67 (69–76), f1–f1 51 (36–50), f2–f2 140 (128–140), f1–f2 45 (39–45), h1–h1 83 (80–83), h2–h2 109 (95–120), h3–h3 145 (133–140), h1–h2 28 (17–25), h1–h3 39 (25–47), h2–h3 19 (16–23). Idiosomatic venter (Fig. 11A): apodemes 1 (ap1) well developed, not reaching to slightly shorter apodemes 2; sejugal apodeme weakly developed laterally; apodemes 3 and 4 well formed but not connected medially; coxal fields 1–4 with tiny dimples and blunt setae. Anal region with two pairs of microsetae ad1 and ps3, flanked laterally by minute, blunt setae ps1 and ps2. Lengths of setae: 1a 10 (10–13), 1b 10 (10–12), 1c 8 (9–10), 2a 6 (8–10), 2b 10 (9–10), 3a 10 (9–11), 3b 13 (12–13), 3c 10 (10–11), 4a 13 (11–13), ps1 4 (2–4) and ps2 4 (3–4); intervals between setae: 1a–1b 47 (42–48), 1b–1c 50 (42–47), 1a–1c 42 (36–39), 1a–2a 48 (47–55), 2a–2b 22 (20–27), 3a–3a 36 (37–37), 3b–3c 48 (42–42), 3c–4a 58 (58–59) and 3b–4a 97 (86–92). Legs (Fig. 12): Lengths of leg segments are as follows: leg I: Tr 36 (31–39), Fe 31 (36–39), Ge 16 (16–16), Ti 16 (16–22), Ta 23 (23–27); leg II: Tr 28 (31–31), Fe 41 (33–39), Ge 14 (14–19), Ti 16 (12–20), Ta 23 (23–23); leg III: Tr 39 (36–47), Fe 31 (31–34), Ge 16 (12–16), Ti 14 (16–20), Ta 27 (23–33); and leg IV: Tr 37 (42–48), Fe 39 (34–39), Ge 16 (14–16), Ti 16 (16–22), Ta 36 (25–31). Figure 12. View largeDownload slide Dytiscacarus iranicus sp. nov. (deutonymph). Dorsal aspects of legs I–IV, with separate ventral aspects of tarsi. A, leg I. B, leg II. C, leg III. D, leg IV. Figure 12. View largeDownload slide Dytiscacarus iranicus sp. nov. (deutonymph). Dorsal aspects of legs I–IV, with separate ventral aspects of tarsi. A, leg I. B, leg II. C, leg III. D, leg IV. Leg I 109 (109–114) (Fig. 12A): Tarsus: setae ft’ 4 (3–4) and ft” 3 (4–5) thin, minute, ft” very close to solenidion ω, tc’ 19 (19–24) and tc” 25 (21–22) longer than other tarsal setae, solenidion ω 19 (17–20) baculiform, interval between setae (pv) bases 9 (7–9); tibia: seta v’ 9 (8–11) blunt, longer than blunt l’, l” and v” 5 (4–8), setae (l) small, stiff, d 68 (58–78) whip like, attenuated, longer than other leg setae; genu: d 16 (14–24) and v’ 15 (10–15) longer than other genual setae, setae (l) subequal, blunt, minute; femur: d 56 (49–68) attenuated, longer than other femoral setae, v” 14 (15–16) blunt, longer than blunt setae (l); and trochanter: v 5 (8–9) shorter than seta v’ on genu. Leg II 94 (101–109) (Fig. 12B): Tarsus: setae tc’ 19 (21–26) and tc” 26 (23–24), subequal, attenuated, longer than setae (pv), solenidion ω 22 (20–22) baculiform, as long as tarsus I solenidion, interval between setae (pv) bases 8 (8–9) shorter than genual seta d; tibia: blunt setae v’ 12 (8–11) and v” 6 (6–6) shorter than attenuated, whip-like seta d 73 (68–75) which is longer than other leg setae, setae (l) minute, stiff; genu: d 15 (10–15) as long as blunt v’ 13 (10–15); femur: d 34 (35–49) attenuated, longer than other femoral setae, v” 15 (13–15) blunt, longer than seta v on trochanter, setae (l) stiff, minute; and trochanter: seta v 5 (5–9) stiff, blunt. Leg III 117 (95–117) (Fig. 12C): Tarsus: setae tc’ 24 (24–27) shorter than tc” 31 (28–29), both attenuated, longer than setae (pv), interval between setae (pv) bases 8 (7–8) shorter than femoral seta d; tibia: setae v’ 11 (9–11) and v” 9 (7–10) blunt, shorter than attenuated, whip-like d 78 (73–90), which is longer than other leg setae, setae (l) very small, stiff; genu: blunt seta v’ 9 (7–10) shorter than length of segment; femur: d 10 (12–14) shorter than length of segment; and trochanter: blunt seta v 10 (6–9) longer than seta v on Tr II. Leg IV 109 (117–125) (Fig. 12D): Tarsus: seta tc’ 26 (19–29) shorter than tc” 39 (31–34), both attenuated, longer than setae (pv), interval between setae (pv) bases 8 (8–8); tibia: setae v’ 10 (7–13) and v” 10 (10–10) blunt, shorter than attenuated, whip-like seta d 101 (87–107), which is longest of all leg setae; genu: blunt seta v’ 7 (6–7) shorter than tibial seta v’; femur: d 10 (8–10) as long as trochanter seta v; and trochanter: seta v 11 (10–12) shorter than length of segment. Protonymph (Figs 13–15) Milky white colour when alive. Gnathosoma (Figs 13B, 14B): Length of gnathosoma 59 (47–62), width 59 (53–61); stylets 88 (82–89) long; pharynx 22 (22–24) long and 11 (10–11) wide; infracapitulum with setae m 12 (9–13), interval between their bases 9 (10–10). Palpi 18 (18–18), femorogenu with setae dGe 5 (6–7), longer than blunt seta dFe 4 (4–5); tibiotarsus with seta sul 5 (5–6) blunt, shorter than blunt acm 8 (7–9), seta ul’ 11 (10–11) characteristically bent, longer than blunt seta ul” 5 (6–8). Figure 13. View largeDownload slide Dytiscacarus iranicus sp. nov. (protonymph). A, dorsal habitus, without leg setation. B, gnathosoma, dorsal view. Figure 13. View largeDownload slide Dytiscacarus iranicus sp. nov. (protonymph). A, dorsal habitus, without leg setation. B, gnathosoma, dorsal view. Figure 14. View largeDownload slide Dytiscacarus iranicus sp. nov. (protonymph). A, ventral habitus, without leg setation. B, gnathosoma, ventral view. Figure 14. View largeDownload slide Dytiscacarus iranicus sp. nov. (protonymph). A, ventral habitus, without leg setation. B, gnathosoma, ventral view. Idiosoma: Length of idiosoma 383 (385–488), width 323 (280–375). Idiosomatic dorsum (Fig. 13A): PrsC with central plate 220 (225–238) long, 160 (163–168) wide, club shaped, with vi microseta, seta sci longer than ve; each lateral plate 133 (138–143) long and 123 (100–113) wide, with seta c1 longer than subequal sce and c2. Tergite DE 48 (53–65) long and 203 (195–213) wide, ellipsoid, with two pairs of microsetae. Tergite F 48 (43–58) long and 63 (68–75) wide, ellipsoid, divided in two, with two pairs of microsetae. Tergite H 53 (48–55) long and 58 (60–75) wide, divided, with three pairs of microsetae. All dorsal plates with tiny dimples; lengths of setae: ve 10 (10–10), sci 12 (12–15), sce 10 (10–11), c1 15 (14–16), c2 11 (11–15); intervals between setae: vi–vi 33 (23–35), ve–ve 101 (105–108), sci–sci 73 (75–78), vi–ve 45 (45–51), vi–sci 86 (81–86), sci–ve 56 (48–55), c1–sce 75 (75–80), c1–c2 56 (56–62), c2–sce 53 (50–56), d–d 50 (48–62), e–e 156 (158–181), d–e 55 (45–61), f1–f2 34 (33–39), h1–h2 14 (9–25), h1–h3 28 (24–37) and h2–h3 11 (14–14). Idiosomatic venter (Fig. 14A): apodeme 1 (ap1) moderately developed, not reaching to similarly developed apodeme 2; apodemes 3 and 4 well formed but not connected medially; coxal fields 1–4 with tiny dimples and blunt, stiff setae. Anal region without setae. Lengths of setae: 1a 9 (8–9), 1b 9 (9–10), 1c 4 (3–4), 2a 5 (3–5), 2b 5 (4–4), 3a 5 (6–7), 3b 8 (8–9), 3c 3 (4–5), 4a 4 (m-3); intervals between setae: 1a–1b 41 (39–41), 1b-1c 39 (39–45), 1a–1c 34 (36–42), 1a–2a 39 (39–48), 2a–2b 20 (22–27), 3a–3a 22 (19–28), 3b–3c 41 (34–39), 3c–4a 47 (36–64) and 3b–4a 76 (67–80). Legs (Fig. 15): Lengths of leg segments are as follows: leg I: Tr 27 (27–39), Fe 31 (31–33), Ge 14 (12–14), Ti 16 (14–16), Ta 23 (20–23); leg II: Tr 23 (27–30), Fe 31 (28–31), Ge 12 (12–12), Ti 11 (12–14), Ta 22 (22–23); leg III: Tr 42 (37–42), Fe 30 (27–31), Ge 12 (12–14), Ti 12 (12–16), Ta 20 (22–23); and leg IV: Tr 36 (36–39), Fe 30 (23–31), Ge 16 (11–14), Ti 11 (12–16), Ta 20 (20–23). Figure 15. View largeDownload slide Dytiscacarus iranicus sp. nov. (protonymph). Dorsal aspects of legs I–IV, with separate ventral aspects of tarsus I. A, leg I. B, leg II. C, leg III. D, leg IV. Figure 15. View largeDownload slide Dytiscacarus iranicus sp. nov. (protonymph). Dorsal aspects of legs I–IV, with separate ventral aspects of tarsus I. A, leg I. B, leg II. C, leg III. D, leg IV. Leg I 86 (86–94) (Fig. 15A): Tarsus: setae ft’ 3 (3–4) and ft” 3 (2–3) thin, minute, ft” very close to solenidion ω, tc’ 21 (20–21) and tc” 17 (17–18) longer than baculiform solenidion ω 15 (14–17), interval between setae (pv) bases 9 (8–9); tibia: seta v’ 3 (5–5) blunt, longer than blunt l’, seta v” 3 (5–5) blunt, longer than minute l”, d 56 (52–63) whip like, attenuated, longer than other leg setae; genu: d minute (m-3), microsetae (l), v’ 3 (3–4) longer than other genual setae; femur: d 17 (22–26) attenuated, longer than other femoral setae, v” 8 (5–9) blunt, longer than minute setae (l); and trochanter: microseta v. Leg II 78 (78–90) (Fig. 15B): Tarsus: setae tc’ 13 (15–15) and tc” 15 (15–17), subequal, attenuated, longer than setae (pv), solenidion ω 18 (16–18) baculiform, interval between seta (pv) bases 8 (8–9) longer than tibial seta v’; tibia: blunt setae v’ 6 (5–6) and v” 5 (4–5) shorter than attenuated, whip-like d 53 (44–58), which is longer than other leg setae, setae (l) minute; genu: d and v’ microsetae; femur: d 34 (35–49) attenuated, longer than other femoral setae, v” 5 (6–7) blunt, longer than minute setae (l); and trochanter: microseta v. Leg III 94 (94–97) (Fig. 15C): Tarsus: setae tc’ 15 (16–19) and tc” 16 (15–19) subequal, attenuated, longer than setae (pv), interval between setae (pv) bases 8 (7–9); tibia: setae v’ 5 (6–7) and v” 6 (5–6) subequal, blunt, shorter than attenuated, whip-like d 55 (44–53), which is longer than other leg setae, setae (l) minute; genu: seta v’ minute; femur: seta d 5 (m-6) blunt, minute; and trochanter: v vestigial. Leg IV 86 (89–94) (Fig. 15D): Tarsus: setae tc’ 16 (15–19) and tc” 16 (16–19) subequal, attenuated, longer than setae (pv), interval between setae (pv) bases 8 (6–8); tibia: setae v’ 4 (2–6) and v” 4 (5–5) blunt, longer than minute (l), seta d 53 (58–73) attenuated, whip like, longest of all leg setae, setae (l) minute; genu: without seta; femur: d microseta; and trochanter: v vestigial. Larva (Figs 16–18) Milky white colour when alive. Gnathosoma (Figs 16B, 17B): Length of gnathosoma 58 (52–58), width 57 (49–55); stylets 82 (82–86) long; pharynx 19 (20–21) long and 11 (10–10) wide; infracapitulum with setae m 15 (12–14), interval between their bases 8 (8–9). Palpi 18 (17–18) long, femorogenu with setae dGe 7 (4–6), longer than blunt dFe 3 (4–5); tibiotarsus with setae sul 5 (4–6) and acm 6 (5–6) blunt, subequal, ul’ 10 (9–10) characteristically bent, longer than blunt seta ul” 8 (6–6). Figure 16. View largeDownload slide Dytiscacarus iranicus sp. nov. (larva). A, dorsal habitus, without leg setation. B, gnathosoma, dorsal view. Figure 16. View largeDownload slide Dytiscacarus iranicus sp. nov. (larva). A, dorsal habitus, without leg setation. B, gnathosoma, dorsal view. Idiosoma: Length of idiosoma 335 (325–400), width 278 (288–295). Idiosomatic dorsum (Fig. 16A): PrsC with central plate 183 (175–180) long, 145 (128–150) wide, club shaped, with vi microsetae, seta sci longer than ve; each lateral plate 103 (108–110) long and 88 (83–88) wide, kidney shaped, seta sce slightly longer than subequal c1 and c2. Tergite DE 50 (45–55) long and 72 (68–71) wide, ellipsoid, divided, with two pairs of microsetae. Tergite F 35 (33–45) long and 55 (50–58) wide, ellipsoid, divided, with two pairs of microsetae. Tergite H absent, microsetae h1–h3, on striated cuticle. All dorsal plates with tiny dimples; all dorsal setae blunt; lengths of setae: ve 7 (7–8), sci 10 (9–12), sce 9 (8–9), c1 8 (6–8) and c2 7 (6–8); intervals between dorsal setae: vi–vi 25 (23–25), ve–ve 97 (83–98), sci–sci 50 (62–69), vi–ve 50 (36–45), vi–sci 76 (67–72), sci–ve 48 (47–48), c1–sce 58 (56–58), c1–c2 42 (36–41), c2–sce 41 (37–41), d–e 36 (33–37) and f1–f2 28 (25–31). Idiosomatic venter (Fig. 17A): apodemes 1 (ap1) moderately developed, not reaching to similarly developed apodemes 2; sejugal apodeme not developed; apodemes 3 not developed; coxal fields 1 with seta 1a 18 (15–20) longer than seta 1b 15 (13–15), interval between them 80 (68–78); coxal fields 3 with seta 3a 15 (15–20) as long as 1a; all ventral setae blunt; anal region without setae. Figure 17. View largeDownload slide Dytiscacarus iranicus sp. nov. (larva). A, ventral habitus, without leg setation. B, gnathosoma, ventral view. Figure 17. View largeDownload slide Dytiscacarus iranicus sp. nov. (larva). A, ventral habitus, without leg setation. B, gnathosoma, ventral view. Legs (Fig. 18): Length of leg segments is as follows: leg I: Tr 25 (22–23), Fe 28 (23–28), Ge 9 (9–12), Ti 12 (11–12), Ta 19 (19–22); leg II: Tr 20 (12–22), Fe 23 (23–31), Ge 8 (9–9), Ti 12 (11–11), Ta 20 (16–19); and leg III: Tr 28 (23–31), Fe 23 (19–19), Ge 9 (8–9), Ti 12 (11–12), Ta 20 (19–22). Figure 18. View largeDownload slide Dytiscacarus iranicus sp. nov. (larva). Dorsal aspects of legs I–III, with separate ventral aspects of tarsi. A, leg I. B, leg II. C, leg III. Figure 18. View largeDownload slide Dytiscacarus iranicus sp. nov. (larva). Dorsal aspects of legs I–III, with separate ventral aspects of tarsi. A, leg I. B, leg II. C, leg III. Leg I 78 (67–78) (Fig. 18A): Tarsus: setae (ft) 2 (2–2) minute, ft” close to solenidion ω, eupathidial tc’ 19 (19–20) and tc” 20 (16–20) longer than baculiform solenidion ω 12 (14–15), setae (pv) attenuated, interval between their bases 6 (6–7); tibia: setae v’ 4 (2–3) and v” 3 (3–3) blunt, minute, (l) microsetae, d 49 (44–53) attenuated, whip like, longer than other leg setae; genu: microsetae (l) hardly visible; femur: d minute, l’, l” and v” microsetae; and trochanter: no seta discernible. Leg II 70 (62–73) (Fig. 18B): Tarsus: setae tc’ 14 (12–14) and tc” 14 (14–17), attenuated, longer than setae (pv), solenidion ω 16 (12–15) baculiform, longer than tibial setae (v), interval between setae (pv) bases 7 (6–8) longer than tibial seta v”; tibia: blunt setae v’ 3 (2–4) and v” 4 (2–3) minute, but longer than microsetae (l), d 39 (41–49) attenuated, whip like, longer than other leg setae; genu: without seta; femur: d and v” microsetae; and trochanter: no seta discernible. Leg III 86 (69–80) (Fig. 18C): Tarsus: setae tc’ 16 (15–18) and tc” 13 (13–16) attenuated, longer than setae (pv), interval between setae (pv) bases 6 (5–7) longer than genual setae (v); tibia: setae v’ 3 (2–4) and v” 3 (2–3) blunt, subequally minute, but longer than microsetae (l), d 34 (31–39) attenuated, whip like, longer than other leg setae; genu: without seta; femur: d microseta; and trochanter: no seta discernible. Differential diagnosis Adult D. iranicus differ from those of the two newly described Nearctic species of the genus as follows. Female: Pseudanal setae ps1 and ps2 are shorter (5–8 µm); these setae are longer (9–13 µm) in both Nearctic congeners; legs I–II genual setae d and v’ are similar in length (v’ is two to three times longer than d in both Nearctic congeners). Male: Platelets bearing setae f1 are smaller (subcircular, scarcely wider than long) and well separated; these platelets are larger, clearly wider than long, and closer to each other in both Nearctic congeners; the genital capsule is smaller relative to body size, such that the dorsal plate PrsCDE is about four times as long as the capsule; the dorsal plate is at most three (2.7–2.9) times as long as the capsule in both Nearctic congeners; leg II tibial seta d is twice as long as femoral seta d (these setae are more similar in length, with tibial d at most 1.5 longer than femoral d in the Nearctic congeners). Apart from minor differences in lengths of setae and other structures, some of which are correlated with overall differences in body sizes, each of the immature instars of these species is very similar. In deutonymphs, leg II femoral seta d is relatively shorter (about one-third as long as the leg length) in D. iranicus, whereas it is about one-half the leg length in the Nearctic species. Type material Holotype: Female (AM 13-0413-003), found in vicinity of Sirik city, Hormozgan Province, southern Iran, (26°24′56.1″N, 57°13′23.5″E, elevation 20 m) detached under elytra of Hydaticus pictus (Sharp, 1882) (Insecta: Coleoptera: Dytiscidae: Dytiscinae, Hydaticini), collected by Abdolazim Mortazavi, 13 April 2013, deposited in the Acarological Collection, Department of Entomology, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran. Paratypes: One female, two males, five deutonymphs, four protonymphs and four larvae, from the same beetle host, with the same collection data as the holotype. Two deutonymphs, one protonymph and one larva are deposited in Canadian National Collection of Insects, Arachnids and Nematodes, Science and Technology Branch, Agriculture and Agri-Food Canada, Ottawa, ON, Canada. The remaining paratypes and the insect host (which is denoted as the host specimen) are retained with the holotype. Etymology The specific epithet refers to country of origin, Iran. Dytiscacarus americanus Mortazavi and Hajiqanbar sp. nov. (Figs 19–33) Description Adult female (Figs 19–21). Gnathosoma (Figs 19, 20): Length of gnathosoma 55 (53), width 53 (53). Length of stylets 95 (87); pharynx 26 (21) long and 12 (11) wide; infracapitulum with setae m 12 (15), interval between their bases 10 (9). Palpi 23 (17) long, femorogenu with setae dFe 5 (5) and dGe 12 (11), dGe longer than blunt dFe; tibiotarsus with seta sul 5 (6) blunt, shorter than blunt acm 6 (7), seta ul’ 10 (13) characteristically bent, longer than blunt ul” 6 (5). Figure 19. View largeDownload slide Dytiscacarus americanus sp. nov. (female). Dorsal habitus, without leg setation. Figure 19. View largeDownload slide Dytiscacarus americanus sp. nov. (female). Dorsal habitus, without leg setation. Figure 20. View largeDownload slide Dytiscacarus americanus sp. nov. (female). Ventral habitus, without leg setation. Figure 20. View largeDownload slide Dytiscacarus americanus sp. nov. (female). Ventral habitus, without leg setation. Idiosoma: Length of idiosoma 388 (338), width 295 (268). Idiosomatic dorsum (Fig. 19) with length of plate PrsCDE 273 (263), width 285 (265), with microsetae vi, d, e, setae ve and c2 subequal and shorter than other PrsCDE setae, sci, sce, c1 subequal. Tergite F 23 (20) long and 78 (83) wide, with two pairs of microsetae. Tergite H 48 (55) long and 73 (75) wide, subquadrate, with three pairs of microsetae, interval between h3 bases greater than that between h2 bases. All dorsal plates with tiny dimples. Lengths of setae: ve 8 (11), sci 14 (14), sce 12 (11), c1 11 (12) and c2 10 (11); intervals between setae: vi–vi 23 (17), ve–ve 90 (81), sci–sci 66 (66), vi–ve 42 (39), vi–sci 87 (80), sci–ve 61 (50), sce–sce 237 (222), c1–c1 126 (114), c2–c2 256 (248), c1–sce 75 (73), c1–c2 69 (61), c2–sce 55 (53), d–d 46 (34), e–e 122 (95), d–e 37 (39), f1–f1 35 (23), f2–f2 61 (59), f1–f2 13 (22), h1–h1 29 (37), h2–h2 41 (45), h3–h3 53 (61), h1–h2 20 (14), h1–h3 32 (17) and h2–h3 11 (10). Idiosomatic venter (Fig. 20): apodemes 1 well developed, not connecting with subequal apodemes 2, sejugal apodeme weakly developed laterally; apodemes 3 and 4 well developed but not connected medially; coxal fields 1–4 with tiny dimples and needle-like setae. Anal region with setae ad1 tiny, blunt ps3 microsetae (hardly visible in paratype), setae ps1 and ps2 distinctly stouter than ad1, both stiff. Lengths of setae: 1a 16 (17), 1b 15 (15), 1c 15 (15), 2a 16 (15), 2b 18 (18), 3a 15 (15), 3b 19 (17), 3c 21 (19), 4a 19 (18), ad1 5 (m), ps1 12 (14) and ps2 11 (13); intervals between setae: 1a–1b 44 (45), 1b–1c 39 (41), 1a–1c 39 (39), 1a–2a 47 (47), 2a–2b 23 (25), 3a–3a 36 (36), 3b–3c 28 (34), 3c–4a 55 (50) and 3b–4a 73 (72). Legs (Fig. 21): Legs I and II shorter than other legs, leg IV longest. Lengths of leg segments are as follows: leg I: Tr 31 (31), Fe 55 (51), Ge 23 (22), Ti 31 (25), Ta 31 (39); leg II: Tr 34 (23), Fe 47 (44), Ge 25 (20), Ti 23 (20), Ta 31 (39); leg III: Tr 37 (31), Fe 59 (53), Ge 23 (20), Ti 27 (23), Ta 47 (55); and leg IV: Tr 42 (39), Fe 70 (66), Ge 30 (25), Ti 28 (23), Ta 56 (55). Figure 21. View largeDownload slide Dytiscacarus americanus sp. nov. (female). Dorsal aspects of legs I–IV, with separate ventral aspects of tarsi. A, leg I. B, leg II. C, leg III. D, leg IV. Figure 21. View largeDownload slide Dytiscacarus americanus sp. nov. (female). Dorsal aspects of legs I–IV, with separate ventral aspects of tarsi. A, leg I. B, leg II. C, leg III. D, leg IV. Leg I 148 (142) (Fig. 21A): Tarsus: setae (ft) thin, ft” 5 (5) coupled with solenidion ω and shorter than ft’ 7 (6), tc’ 11 (14) and tc” 14 (13) longer than other tarsal setae, solenidion ω 10 (11) baculiform; tibia: seta v’ 19 (20), longer than l’, l” and v” 5 (7), seta d 73 (69) whip like, attenuated, longer than other leg setae; genu: d 13 (10) and v’ 29 (25) longer than other genual setae, v’ longer than d, setae l’ longer than l”; femur: d 68 (54) attenuated, longer than other femoral setae, v” 34 (35) attenuated, longer than stiff setae l’ and l”; and trochanter: seta v 25 (24) shorter than length of segment. Leg II 140 (125) (Fig. 21B): Tarsus: setae tc’ 24 (20) and tc” 24 (23), seta tc’ longer than (pv), solenidion ω 14 (15) baculiform, longer than tarsus I solenidion; tibia: seta v’ 19 (26) longer than v” 10 (10), both shorter than attenuated, whip-like seta d 76 (73), which is longer than other leg setae; genu: d 10 (9) shorter than seta v’ 20 (24); femur: d 58 (49) attenuated, whip like, longer than other femoral setae, seta v” 35 (34) attenuated, longer than l’ and l”, seta l’ longer than l”; and trochanter: seta v 21 (24) shorter than length of segment. Leg III 164 (156) (Fig. 21C): Tarsus: setae tc’ 21 (25) and tc” 24 (24) subequal, longer than (pv); tibia: setae v’ 15 (12) longer than v” 10 (12), whip-like seta d 87 (78) longer than other leg setae; genu: v’ 15 (8) shorter than length of segment; femur: d 18 (15) attenuated, longer than genual seta v’; and trochanter: seta v 29 (26) shorter than length of segment. Leg IV 218 (195) (Fig. 21D): Tarsus: setae tc’ 21 (14) and tc” 29 (24) attenuated, tc” longer than setae (pv); tibia: setae v’ 15 (12) and v” 15 (11) subequal, attenuated and whip-like seta d 113 (107) longest of all leg setae; genu: v’ 14 (10) shorter than length of segment; femur: d 19 (15) longer than genual seta l’; and trochanter: seta v 24 (24) shorter than length of segment. Male (Figs 22–24) Shorter than adult female. Gnathosoma (Figs 22, 23): Length of gnathosoma 40 (41), width 47 (49). Stylets 78 (81) long; pharynx length 24 (19) and width 9 (9); infracapitulum with setae m 13 (12), interval between their bases 8 (8). Palpi 16 (19) long, femorogenu with setae dFe 4 (3) and dGe 11 (7), dGe twice as long as blunt dFe; tibiotarsus with seta sul 4 (5) blunt, shorter than blunt acm 6 (5), seta ul’ 12 (10) characteristically bent, longer than blunt ul” 6 (5). Figure 22. View largeDownload slide Dytiscacarus americanus sp. nov. (male). Dorsal habitus, without leg setation. Figure 22. View largeDownload slide Dytiscacarus americanus sp. nov. (male). Dorsal habitus, without leg setation. Figure 23. View largeDownload slide Dytiscacarus americanus sp. nov. (male). Ventral habitus, without leg setation. Figure 23. View largeDownload slide Dytiscacarus americanus sp. nov. (male). Ventral habitus, without leg setation. Idiosoma: Length of idiosoma 332 (320), width 309 (250). Idiosomatic dorsum (Fig. 22) with length of plate PrsCDE 224 (210), width 237 (250), with microsetae vi and d, setae e shorter and sci longer than other PrsCDE setae, ve, sci, c1 and c2 subequal; posterior margin of plate PrsCDE with a deep, narrow incision of soft cuticle medially between setae d. Outer platelets F 5 (9) long and 8 (6) wide, round, weakly sclerotized, each with one microseta; inner platelet F 13 (9) long and 34 (23) wide, ellipsoid, weakly sclerotized, each with one microseta. Genital capsule 75 (86) long and 82 (76) wide, subquadrate, with four pairs of microsetae, interval between h1 bases shorter than that between ps1 bases, length of aedeagus 89 (87), length of claspers 40 (39). All dorsal plates and genital capsule with tiny dimples. Lengths of setae: ve 11 (10), sci 18 (19), sce 12 (12), c1 13 (12), c2 13 (10) and e 3 (4); intervals between setae: vi–vi 17 (20), ve–ve 82 (81), sci–sci 66 (55), vi–ve 32 (30), vi–sci 55 (68), sci–ve 42 (47), sce–sce 171 (178), c1–c1 92 (78), c2–c2 200 (188), c1–sce 63 (70), c1–c2 53 (53), c2–sce 41 (39), d–d 39 (41), e–e 146 (140), d–e 50 (53), h1–h1 41 (–), h2–h2 61 (–), h3–h3 71 (–), h1–h2 17 (–), h1–h3 32 (–), h2–h3 15 (–), ps1–ps1 61 (–) and h3–ps1 9 (–) (in paratype, interval between genital capsule setae not measurable). Idiosomatic venter (Fig. 23): apodemes 1 well developed but not reaching to slightly longer apodemes 2; sejugal apodeme weakly developed laterally; apodemes 3 and 4 well developed but not connected medially; coxal fields 1–4 with tiny dimples, all ventral setae stiff except 1c (microseta). Lengths of setae: 1a 8 (9), 1b 8 (7), 2a 5 (5), 2b 5 (4), 3a 5 (5), 3b 8 (9), 3c 4 (3)4 (3) and 4a 4 (2); interval between setae: 1a–1b 34 (34), 1b–1c 37 (39), 1a–1c 37 (36), 1a–2a 39 (46), 2a–2b 24 (22), 3a–3a 43 (51), 3b–3c 36 (34), 3c–4a 55 (53) and 3b–4a 76 (77). Legs (Fig. 24): Legs I thicker than others; all legs subequal in length. Length of leg segments is as follows: leg I: Tr 42 (35), Fe 37 (34), Ge 17 (15), Ti 16 (12), Ta 23 (20); leg II: Tr 36 (33), Fe 37 (34), Ge 16 (14), Ti 18 (14), Ta 24 (20); leg III: Tr 38 (33), Fe 37 (34), Ge 13 (12), Ti 15 (16), Ta 27 (27); and leg IV: Tr 43 (37), Fe 43 (37), Ge 15 (16), Ti 16 (16), Ta 25 (23). Figure 24. View largeDownload slide Dytiscacarus americanus sp. nov. (male). Dorsal aspects of legs I–IV, with separate ventral aspects of tarsi. A, leg I. B, leg II. C, leg III. D, leg IV. Figure 24. View largeDownload slide Dytiscacarus americanus sp. nov. (male). Dorsal aspects of legs I–IV, with separate ventral aspects of tarsi. A, leg I. B, leg II. C, leg III. D, leg IV. Leg I 97 (109) (Fig. 24A): Tarsus: setae tc’ 14 (15) and tc” 18 (18) stiff, blunt, setae (ft) microsetae, (u) and (p) blunt, seta ft” very close to baculiform solenidion ω 11 (12), setae (a) subequal and blunt, interval between setae (pv) bases 6 (6); tibia: seta v’ 5 (4) blunt, l’ and v” 4 (3) blunt, setae l” and d microsetae; genu: setae d, l’ and l” microsetae, seta v’ 5 (3) stiff, blunt; femur: d 21 (18), longer than other femoral setae, v” 9 (9) blunt, longer than blunt setae l’ and l”; and trochanter: seta v 7 (5) tiny, blunt. Leg II 97 (86) (Fig. 24B): Tarsus: setae tc’ 10 (13) shorter than tc” 16 (15), tc” longer than (pv), setae (u) and (p) blunt, solenidion ω 19 (19) baculiform, longer than tarsus I solenidion, interval between bases of setae (pv) 6 (5), as long as tibial seta v’; tibia: seta v’ 6 (5) longer than v” 5 (3), both blunt, shorter than attenuated, whip-like seta d 37 (22), setae (l) minute; genu: d microseta, v’ 9 (5) stiff, blunt; femur: d 32 (25) longer than segment, v” 11 (10) blunt, longer than small, blunt (l); and trochanter: blunt seta v small 7 (8). Leg III 97 (94) (Fig. 24C): Tarsus: setae tc’ 12 (13) shorter than tc” 15 (13), longer than (pv), setae (u) and (p) blunt, interval between bases of setae (pv) 7 (6) greater than length of seta v’ on genu; tibia: setae v’ 8 (6) and v” 6 (4) blunt, stiff, shorter than attenuated, whip-like seta d 64 (78), setae (l) minute; genu: v’ 5 (4) blunt; femur: seta d 8 (6) blunt, longer than v’ on genu; and trochanter: seta v 7 (8) blunt, stiff. Leg IV 113 (101) (Fig. 24D): Tarsus: setae tc’ 15 (15) and tc” 14 (13) attenuated, longer than setae (pv), setae (u) and (p) blunt, interval between bases of setae (pv) 6 (6) greater than length of seta v’ on genu; tibia: setae v’ 7 (11) and v” 7 (6) blunt, stiff, shorter than attenuated, whip-like seta d 84 (78), which is longest of all leg setae, setae (l) minute; genu: seta v’ 5 (3) blunt, stiff; femur: seta d 8 (5) blunt, longer than seta v’ on genu; and trochanter: blunt seta v 5 (7) shorter than v on Tr III. Deutonymph (Figs 25–27) Gnathosoma (Figs 25, 26): Length of gnathosoma 55 (62), width 62 (61). Stylets 92 (96) long; pharynx 26 (29) long and 14 (10) wide, infracapitulum with setae m 13 (13), interval between their bases 10 (10). Palpi 19 (19), femurogenu with setae dGe 10 (11) twice as long as blunt dFe 5 (5); tibiotarsus with seta sul 4 (4) blunt, shorter than blunt acm 6 (5), seta ul’ 12 (9) characteristically bent, pointed, longer than blunt seta ul” 7 (6). Figure 25. View largeDownload slide Dytiscacarus americanus sp. nov. (deutonymph). Dorsal habitus, without leg setation. Figure 25. View largeDownload slide Dytiscacarus americanus sp. nov. (deutonymph). Dorsal habitus, without leg setation. Figure 26. View largeDownload slide Dytiscacarus americanus sp. nov. (deutonymph). Ventral habitus, without leg setation. Figure 26. View largeDownload slide Dytiscacarus americanus sp. nov. (deutonymph). Ventral habitus, without leg setation. Idiosoma: Length of idiosoma 480 (463), width 340 (353). Idiosomatic dorsum (Fig. 25): PrsC with central plate 263 (263) long and 178 (168) wide, club shaped, with vi microsetae, setae ve shorter than sci; each lateral plate 175 (175) long and 133 (125) wide, kidney shaped, seta sce shorter than subequal setae c1 and c2. Tergite DE 65 (68) long and 268 (243) wide, ellipsoid, with two pairs of microsetae. Tergite F 43 (50) long and 175 (175) wide, ellipsoid, thinner than other tergites, with two pairs of microsetae. Tergite H 63 (75) long and 160 (155) wide, ellipsoid, with three pairs of microsetae, interval between h1 bases subequal to that between h2. All dorsal plates with tiny dimples. Lengths of setae: ve 11 (12), sci 14 (15), sce 12 (11), c1 16 (15) and c2 15 (14); intervals between setae: vi–vi 30 (23), ve–ve 111 (108), sci–sci 78 (64), vi–ve 48 (62), vi–sci 103 (101), sci–ve 76 (55), c1–sce 92 (97), c1–c2 75 (76), c2–sce 59 (61), d–d 64 (61), e–e 169 (197), d–e 86 (69), f1–f1 47 (56), f2–f2 134 (122), f1–f2 39 (38), h1–h1 75 (–), h2–h2 75 (–), h3–h3 89 (–), h1–h2 23 (–), h1–h3 60 (–) and h2–h3 12 (–) (interval between setae in tergite H not measurable in paratype). Idiosomatic venter (Fig. 26): apodemes 1 well developed, not reaching to slightly shorter apodemes 2; sejugal apodeme weakly developed laterally; apodemes 3 and 4 well formed but not connected medially; coxal fields 1–4 with tiny dimples. Anal region with two pairs of microsetae ad1 and ps3; flanked laterally by minute, blunt setae ps1 and ps2. Lengths of setae: 1a 13 (11), 1b 8 (10), 1c 10 (12), 2a 10 (11), 2b 9 (10), 3a 10 (10), 3b 14 (12), 3c 10 (11), 4a 11 (10), ps1 7 (8) and ps2 6 (8); intervals between setae: 1a–1b 47 (41), 1b–1c 41 (42), 1a–1c 39 (39), 1a–2a 53 (50), 2a–2b 31 (23), 3a–3a 39 (48), 3b–3c 47 (42), 3c–4a 66 (62) and 3b–4a 98 (90). Legs (Fig. 27): Lengths of leg segments are as follows: leg I: Tr 42 (31), Fe 34 (34), Ge 16 (12), Ti 12 (16), Ta 25 (23); leg II: Tr 41 (31), Fe 31 (31), Ge 12 (12), Ti 17 (14), Ta 22 (23); leg III: Tr 47 (47), Fe 31 (25), Ge 14 (14), Ti 14 (16), Ta 25 (25); and leg IV: Tr 48 (47), Fe 39 (39), Ge 16 (12), Ti 12 (14), Ta 23 (23). Figure 27. View largeDownload slide Dytiscacarus americanus sp. nov. (deutonymph). Dorsal aspects of legs I–IV, with separate ventral aspects of tarsi. A, leg I. B, leg II. C, leg III. D, leg IV. Figure 27. View largeDownload slide Dytiscacarus americanus sp. nov. (deutonymph). Dorsal aspects of legs I–IV, with separate ventral aspects of tarsi. A, leg I. B, leg II. C, leg III. D, leg IV. Leg I 109 (101) (Fig. 27A): Tarsus: setae ft’ 5 (5) and ft” 4 (3) thin, minute, ft” very close to solenidion ω, tc’ 19 (19) and tc” 19 (18) subequal, as long as setae (pv), solenidion ω 15 (16) baculiform, setae (pv) attenuated, interval between their bases 6 (7); tibia: subequal setae v’ 6 (8) and v” 5 (6) longer than setae l’ and blunt l”, seta d 68 (82) whip like, attenuated, longer than other leg setae; genu: d 6 (6) and v’ 10 (14) longer than other genual setae, seta l’ longer than blunt l”; femur: d 44 (60) attenuated, longer than other femoral setae, v” 13 (14) longer than tibial setae (v); and trochanter: v 8 (10) shorter than seta v” on femur. Leg II 97 (94) (Fig. 27B): Tarsus: setae tc’ 18 (20) and tc” 23 (23), attenuated, tc’ as long as setae (pv), solenidion ω 18 (19) baculiform, longer than tarsus I solenidion, interval between setae (pv) bases 7 (8) shorter than genual seta v’; tibia: setae v’ 8 (8) and v” 7 (5) shorter than attenuated, whip-like seta d 66 (70), l’ and l” subequal; genu: seta d 6 (6) shorter than seta v’ 15 (12); femur: d 53 (49) attenuated, longer than other femoral setae, v” 15 (13) longer than seta v on trochanter, setae (l) stiff, minute; and trochanter: v 7 (10) longer than seta l’ on femur. Leg III 111 (101) (Fig. 27C): Tarsus: setae tc’ 19 (16) shorter than tc” 26 (18), both attenuated, interval between setae (pv) bases 6 (8) subequal to femoral seta d; tibia: setae v’ 6 (7) and v” 6 (6) shorter than attenuated, whip-like d 80 (87), setae l’ and l” subequal; genu: seta v’ 6 (6) shorter than length of segment; femur: d 8 (10), shorter than length of segment; and trochanter: seta v 10 (10) as long as seta v on Tr II. Leg IV 117 (109) (Fig. 27D): Tarsus: setae tc’ 19 (17) and tc” 19 (17) attenuated, interval between setae (pv) bases 7 (7); tibia: setae v’ 5 (6) and v” 6 (7) blunt, shorter than attenuated, whip-like seta d 73 (63), which is the longest of all leg setae, setae (l) blunt, minute; genu: blunt v’ 5 (6) as long as tibial seta v’; femur: d 10 (10) shorter than length of segment; and trochanter: seta v 10 (10). Protonymph (Figs 28–30) Gnathosoma (Figs 28, 29): Length of gnathosoma 51 (47), width 59 (61); stylets 66 (82) long; pharynx 22 (24) long and 8 (10) wide; infracapitulum with setae m 11 (13), interval between their bases 10 (8). Palpi 18 (19), femorogenu with setae blunt dFe 5 (5) shorter than dGe 7 (7); tibiotarsus with seta sul 5 (4) blunt, shorter than blunt acm 6 (5), seta ul’ 11 (9) characteristically bent, longer than blunt seta ul” 6 (6). Figure 28. View largeDownload slide Dytiscacarus americanus sp. nov. (protonymph). Dorsal habitus, without leg setation. Figure 28. View largeDownload slide Dytiscacarus americanus sp. nov. (protonymph). Dorsal habitus, without leg setation. Figure 29. View largeDownload slide Dytiscacarus americanus sp. nov. (protonymph). Ventral habitus, without leg setation. Figure 29. View largeDownload slide Dytiscacarus americanus sp. nov. (protonymph). Ventral habitus, without leg setation. Idiosoma: Length of idiosoma 401 (325), width 316 (245). Idiosomatic dorsum (Fig. 28): PrsC with central plate 217 (193) long and 155 (160) wide, club shaped, with vi microseta, seta sci longer than ve; each lateral plate 132 (138) long and 92 (88) wide, with setae sce as long as subequal c1 and c2. Tergite DE 59 (58) long and 193 (183) wide, ellipsoid, with two pairs of microsetae. Tergite F 43 (40) long and 67 (63) wide, ellipsoid, divided in two, with two pairs of microsetae. Tergite H 39 (40) long and 46 (50) wide, divided, with three pairs of microsetae. All dorsal plates with tiny dimples. Lengths of setae: ve 8 (9), sci 11 (16), sce 8 (8), c1 9 (10) and c2 8 (8); intervals between setae: vi–vi 41 (30), ve–ve 100 (92), sci–sci 66 (71), vi–ve 37 (38), vi–sci 86 (66), sci–ve 58 (42), c1–sce 78 (67), c1–c2 63 (53), c2–sce 51 (46), d–d 47 (36), e–e 150 (121), d–e 55 (39), f1–f2 36 (34), h1–h2 25 (–), h1–h3 25 (–) and h2–h3 16 (–) (interval between setae in tergite H not measurable in one of the paratypes). Idiosomatic venter (Fig. 29): apodemes 1 moderately developed, not reaching to similarly developed apodeme 2; apodemes 3 and 4 well formed but not connected medially; coxal fields 1–4 with tiny dimples and blunt setae, setae 1c, 3c and 4a microsetae. Anal region without setae. Lengths of setae: 1a 8 (8), 1b 8 (7), 2a 8 (4), 2b 5 (5), 3a 8 (5) and 3b 9 (7); intervals between setae: 1a–1b 36 (34), 1b–1c 36 (33), 1a–1c 33 (25), 1a–2a 46 (47), 2a–2b 30 (31), 3a–3a 41 (27), 3b–3c 36 (34), 3c–4a 45 (47) and 3b–4a 80 (72). Legs (Fig. 30): Lengths of leg segments are as follows: leg I: Tr 25 (27), Fe 25 (27), Ge 12 (11), Ti 12 (12), Ta 17 (23); leg II: Tr 24 (23), Fe 26 (27), Ge 11 (9), Ti 12 (11), Ta 22 (19); leg III: Tr 26 (28), Fe 21 (19), Ge 11 (9)12 (12–14), Ti 12 (12), Ta 21 (17); and leg IV: Tr 30 (23), Fe 18 (23), Ge 9 (12), Ti 14 (11), Ta 21 (16). Figure 30. View largeDownload slide Dytiscacarus americanus sp. nov. (protonymph). Dorsal aspects of legs I–IV, with separate ventral aspects of tarsi. A, leg I. B, leg II. C, leg III. D, leg IV. Figure 30. View largeDownload slide Dytiscacarus americanus sp. nov. (protonymph). Dorsal aspects of legs I–IV, with separate ventral aspects of tarsi. A, leg I. B, leg II. C, leg III. D, leg IV. Leg I 86 (86–94) (Fig. 30A): Tarsus: setae ft’ 2 (3) and ft” 3 (3) thin, minute, seta ft” very close to solenidion ω, tc’ 14 (15) and tc” 14 (14) as long as setae (pv), solenidion ω 13 (16) baculiform, interval between setae (pv) bases 6 (7); tibia: seta v’ 4 (5) and v” 4 (5) blunt, longer than minute (l), seta d 59 (63) attenuated, whip like, longer than other leg setae; genu: d microseta, seta v’ 3 (5) minute, blunt, setae (l) minute; femur: d 13 (15) attenuated, longer than other femoral setae, v” 5 (7) blunt, longer than minute setae (l); and trochanter: v microseta. Leg II 78 (78–90) (Fig. 30B): Tarsus: setae tc’ 13 (16) shorter than seta tc” 19 (19), both attenuated, longer than (pv), solenidion ω 14 (13) baculiform, interval between seta (pv) bases 6 (7) longer than tibial seta v”; tibia: setae v’ 6 (6) and v” 4 (4) blunt, d 66 (63) attenuated, whip like, setae (l) minute; genu: d and l’ microsetae; femur: d 11 (15) longer than other femoral setae, v” 6 (7) blunt, longer than minute setae (l); and trochanter: microseta v. Leg III 94 (94–97) (Fig. 30C): Tarsus: setae tc’ 14 (14) and tc” 18 (15) attenuated, as long as setae (pv), interval between setae (pv) bases 5 (6); tibia: setae v’ 8 (7) and v” 6 (5) blunt, shorter than attenuated, whip-like d 38 (39), which is longer than other leg setae, setae (l) minute; genu: seta v’ minute; femur: d 3 (3) blunt; and trochanter: v microseta. Leg IV 86 (89–94) (Fig. 30D): Tarsus: setae tc’ 16 (21) and tc” 17 (15) attenuated, longer than setae (pv), interval between setae (pv) bases 6 (9); tibia: setae v’ 5 (5) and v” 6 (8) blunt, longer than minute setae (l), seta d 46 (58) attenuated, whip like, longest of all leg setae; genu: without seta; femur: d microseta; and trochanter: v microseta. Larva (Figs 31–33) Gnathosoma (Figs 31, 32): Length of gnathosoma 54 (49–49), width 52 (49–50); stylets 76 (73–73) long; pharynx 17 (16–16) long and 11 (8–10) wide; infracapitulum with setae m 13 (13–14), interval between their bases 8 (7–7). Palpi 16 (13–15) long, femorogenu with setae dFe 4 (4–4) blunt, shorter than dGe 5 (6–7); tibiotarsus with setae sul 4 (4–5) and acm 7 (5–6) blunt, subequal, ul’ 8 (10–10) characteristically bent, longer than blunt seta ul” 5 (5–6). Figure 31. View largeDownload slide Dytiscacarus americanus sp. nov. (larva). Dorsal habitus, without leg setation. Figure 31. View largeDownload slide Dytiscacarus americanus sp. nov. (larva). Dorsal habitus, without leg setation. Figure 32. View largeDownload slide Dytiscacarus americanus sp. nov. (larva). Ventral habitus, without leg setation. Figure 32. View largeDownload slide Dytiscacarus americanus sp. nov. (larva). Ventral habitus, without leg setation. Idiosoma: Length of idiosoma 237 (250–275), width 198 (200–225). Idiosomatic dorsum (Fig. 31): PrsC with central plate 153 (163–173) long and 122 (138–138) wide, club shaped, with vi microsetae, setae sci distinctly longer than ve; each lateral plate 87 (93–100) long and 61 (75–75) wide, kidney shaped, setae sce, c1 and c2 subequal. Tergite DE 40 (40–50) long and 68 (125–128) wide, ellipsoid, divided, with two pairs of microsetae. Tergite F 23 (28–33) long and 47 (45–63) wide, ellipsoid, divided, with two pairs of microsetae. Tergite H absent, microsetae h1 on striated cuticle, setae h2 and h3 invisible; all dorsal plates with tiny dimples; all dorsal setae blunt except sci (pointed). Lengths of setae: ve 7 (5–6), sci 14 (9–13), sce 6 (5–5), c1 5 (4–6) and c2 6 (4–5); intervals between dorsal setae: vi–vi 24 (19–20), ve–ve 85 (97) (not measurable in one of paratypes), sci–sci 68 (78–82), vi–ve 42 (35–44), vi–sci 69 (65–67), sci–ve 39 (39–42), c1–sce 53 (50–61), c1–c2 44 (40–45), c2–sce 34 (37–39), d–e 41 (20–36) and f1–f2 15 (19) (not measurable in one of paratypes). Idiosomatic venter (Fig. 32): apodemes 1 moderately developed, not reaching to similarly developed apodemes 2; sejugal apodeme and apodemes 3 not developed; coxal fields 1 with seta 1a 3 (5–6) as long as 1b 5 (5–6), interval between them 26 (24–29); coxal fields 3 with seta 3a 6 (6–7) as long as 1a; all ventral setae blunt; anal region without setae. Legs (Fig. 33): Lengths of leg segments are as follows: leg I: Tr 18 (19–22), Fe 24 (19–19), Ge 11 (8–9), Ti 11 (11–11), Ta 23 (17–17); leg II: Tr 12 (16–23), Fe 20 (19–20), Ge 9 (6–8), Ti 11 (8–8), Ta 20 (16–20); and leg III: Tr 16 (16–20), Fe 15 (17–17), Ge 8 (6–8), Ti 11 (8–8), Ta 17 (16–16). Figure 33. View largeDownload slide Dytiscacarus americanus sp. nov. (larva). Dorsal aspects of legs I–III, with separate ventral aspects of tarsi. A, leg I. B, leg II. C, leg III. Figure 33. View largeDownload slide Dytiscacarus americanus sp. nov. (larva). Dorsal aspects of legs I–III, with separate ventral aspects of tarsi. A, leg I. B, leg II. C, leg III. Leg I 71 (62–70) (Fig. 33A): Tarsus: setae (ft) 3 (4–4) minute, blunt, ft” close to solenidion ω, eupathidial tc’ 17 (13–15) and tc” 17 (14–16) longer than tarsal baculiform solenidion ω 11 (12–12), setae (pv) attenuated, interval between their bases 5 (5–6); tibia: setae v’ 4 (3–4) and v” 3 (3–3) blunt, longer than blunt setae (l), d 30 (31–49) attenuated, whip like, longer than other leg setae; genu: (l) microsetae; femur: d 4 (2–3) blunt, (l) and v” microsetae; and trochanter: no seta discernible. Leg II 54 (55–58) (Fig. 33B): Tarsus: setae tc’ 11 (15–16) and tc” 11 (12–16), attenuated, longer than setae (pv), solenidion ω 12 (12–14) baculiform, longer than tibial setae (v), interval between setae (pv) bases 5 (5–6) longer than tibial seta v”; tibia: blunt setae v’ 4 (4–4) and v” 3 (3–3) minute, but longer than setae (l), d 30 (34–37) attenuated, whip like, longer than other leg setae, setae (l) small and blunt ended; genu: without seta; femur: d and v” minute; and trochanter: no seta discernible. Leg III 51 (50–55) (Fig. 33C): Tarsus: setae tc’ 12 (14–15) and tc” 13 (15–16) attenuated, longer than setae (pv), interval between setae (vs) bases 5 (6–6) longer than tibial setae (v); tibia: setae v’ 3 (3–5) and v” 3 (3–3) blunt, subequally minute, but longer than minute setae (l), seta d 22 (24–25) attenuated, whip like, longer than other leg setae; genu: without seta; femur: d microseta; and trochanter: no seta discernible. Differential diagnosis For separation of D. americanus from D. iranicus, see the differential diagnosis of the latter species. Adults of D. americanus are distinguished from those of the other Nearctic species, D. thermonecti, by the following characters: on male D. americanus the posterior margin of dorsal plate PrsCDE has a deep, narrow incision of soft cuticle medially between setae d (that margin entire in D. thermonecti and D. iranicus); females of the two Nearctic species are hardly distinguishable; legs III and IV femoral seta d slightly shorter, 15–19 and 15–19 µm, respectively (21–27 and 19–24 µm in D. thermonecti). Despite having slightly larger body dimensions in male D. americanus, setae ve, sci, sce, c1 and c2 are collectively shorter, 8–15 µm (17–20 µm in D. thermonecti). In deutonymphs, leg III femoral seta d is less than two (1.2–1.7) times longer than genual seta v’ (femoral d is three times longer than genual v’ in D. thermonecti). In protonymphs, tibial seta d of legs I–II–III–IV is longer, ~60–60–40–50 µm, respectively (~40–35–30–30 µm in D. thermonecti); leg I tibial seta d is more than three times longer than femoral seta d [tibial d is little more than two (up to 2.4) times longer than femoral d in D. thermonecti]. In larvae, there may be a similar difference in tibial seta d lengths on legs I–II–III, longer, each ~30 µm in D. americanus (each ~20 µm in D. thermonecti), but the condition of the only two larval D. thermonecti microscope slide preparations leaves this comparison uncertain. Type and other material All specimens detached from under elytra of 13 beetles of Hydaticus bimarginatus (Say, 1830) (Insecta: Coleoptera: Dytiscidae: Dytiscinae: Hydaticini) from the following localities in Florida, USA. Holotype: Female, ex H. bimarginatus, from blacklight trap, north end of Heather Island, Marion County, FL, 18 May 1975, coll. P. C. Drummond, deposited in the Canadian National Collection of Insects, Arachnids and Nematodes (CNCI), Science and Technology Branch, Agriculture and Agri-Food Canada, Ottawa, ON, Ontario. Paratypes: One male, two deutonymphs and one protonymph, with the same collection data as the holotype. One male, one deutonymph, two protonymphs and two larvae, with same collection data as holotype except 12 June 1975. Two females, two males and two deutonymphs ex. H. bimarginatus, Baker County, Interstate 250 & Middle Prong, 3 miles N East Tower, 28 July 1976, coll. J. R. Wiley & F. N. Young. One female, one male and two deutonymphs, ex H. bimarginatus from sand pine scrub, Marion County, 9 miles SSW Ocala (KCE), 28 June 1975, coll. P. C. Drummond. One female, ex H. bimarginatus from blacklight trap, Alachua County, Gainesville, 28–31 August 1972, coll. F. W. Mead. One female, one male and one deutonymph, ex H. bimarginatus from blacklight trap, Dade County, S Miami, 5 August 1959, coll. R. W. Swanson. One female and one deutonymph, ex H. bimarginatus in blacklight trap, Flamingo ENP, 24 March 1969, coll. F. W. Mead. One female, two protonymphs and three larvae, ex H. bimarginatus male from buttonwood swamp, Monroe County, Big Pine Key, Watson’s Hammock, 17 August 1992, coll. R. E, Roughley. One male and one deutonymph, ex H. bimarginatus female from hardwood hammock pools, Dade County, Everglades National Park, Royal Palm Hammock, 7 August 1992, coll. R. E. Roughley. One female, one male, one deutonymph and one protonymph deposited in the Acarological Collection, Department of Entomology, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran. The rest of the paratypes are retained with the holotype. The two beetles collected by R. E. Roughley in CNCI are denoted as hosts of these mites. Other material examined, deposited in CNCI: One female, two males, three deutonymphs, one protonymph and one larva, ex H. bimarginatus, Union County, stream 9.7 miles S Olustee on Hwy 231, 28 July 1976, coll. J. R. Wiley & F. W. Young. One larva, ex H. bimarginatus, Marion County, Ross Prairie, 14 miles SW Ocala, 12 June 1975, coll. P. C. Drummond. Etymology The specific epithet refers to country of origin, the United States of ‘America’. Dytiscacarus thermonecti Mortazavi and Hajiqanbar sp. nov. (Figs 34–46) Adult female (Figs 34–36) Gnathosoma (Figs 34, 35): Length of gnathosoma 55 (55–65), width 56 (51–61). Length of stylets 90 (61–89); pharynx 27 (28–29) long and 11 (10–13) wide; infracapitulum with setae m 11 (13–15), interval between their bases 9 (7–11). Palpi 19 (19–21) long, femorogenu with setae dGe 11 (9–12) more than twice as long as blunt dFe 5 (4–6); tibiotarsus with seta sul 5 (3–5) shorter than blunt acm 8 (5–7), seta ul’ 9 (9–12) characteristically bent, longer than blunt ul” 8 (4–7). Figure 34. View largeDownload slide Dytiscacarus thermonecti sp. nov. (female). Dorsal habitus, without leg setation. Figure 34. View largeDownload slide Dytiscacarus thermonecti sp. nov. (female). Dorsal habitus, without leg setation. Figure 35. View largeDownload slide Dytiscacarus thermonecti sp. nov. (female). Ventral habitus, without leg setation. Figure 35. View largeDownload slide Dytiscacarus thermonecti sp. nov. (female). Ventral habitus, without leg setation. Idiosoma: Length of idiosoma 454 (326–497), width 350 (263–287). Idiosomatic dorsum (Fig. 34) with length of plate PrsCDE 282 (268–284), width 303 (263–287), with microsetae vi, d and e, setae ve shorter than other PrsCDE setae, sci and c1 subequal. Tergite F 20 (17–21) long and 83 (67–76) wide, approximately four times wider than long, with two pairs of microsetae. Tergite H 51 (54–65) long and 83 (52–83) wide, almost oval, with three pairs of microsetae, interval between h1 bases longer than that between h3 bases. All dorsal plates with tiny dimples. Lengths of setae: ve 12 (12–16), sci 18 (17–20), sce 14 (14–18), c1 18 (11–16) and c2 14 (14–18); intervals between setae: vi–vi 14 (14–17), ve–ve 88 (85–93), sci–sci 72 (71–78), vi–ve 45 (42–48), vi–sci 79 (78–84), sci–ve 50 (49–52), sce–sce 230 (220–247), c1–c1 111 (104–112), c2–c2 254 (252–257), c1–sce 79 (83–89), c1–c2 71 (69–80), c2–sce 59 (58–63), d–d 54 (34–38), e–e 132 (103–137), d–e 39 (34–52), f1–f1 25 (24–35), f2–f2 62 (54–65), f1–f2 21 (14–24), h1–h1 59 (37–50), h2–h2 58 (40–49), h3–h3 49 (46–50), h1–h2 14 (6–12), h1–h3 22 (14–21) and h2–h3 9 (11–13). Idiosomatic venter (Fig. 35): apodemes 1 well developed, not connecting with slightly shorter apodemes 2; sejugal apodeme weakly developed laterally; apodemes 3 and 4 well developed but not connected medially; coxal fields 1–4 with tiny dimples. Anal region with setae ad1 and ps3 microsetae (ps3 invisible), setae ps1 and ps2 distinctly stouter than ad1, both stiff, blunt. Lengths of setae: 1a 13 (14–16), 1b 12 (12–13), 1c 8 (11–13), 2a 13 (12–14), 2b 13 (11–15), 3a 13 (9–12), 3b 13 (15–16) 3c 20 (17–18), 4a 14 (15–16), ps1 11 (10–11) and ps2 9 (8–10); intervals between setae: 1a–1b 36 (41–45), 1b–1c 36 (37–39), 1a–1c 46 (31–39), 1a–2a 43 (44–49), 2a–2b 24 (18–21), 3b–3c 34 (27–33), 3c–4a 61 (53–56) and 3b–4a 84 (71–74). Legs (Fig. 36): Legs I and II shorter than other legs, leg IV longest. Lengths of leg segments are as follows: leg I: Tr 31 (28–39), Fe 45 (38–47), Ge 26 (24–27), Ti 26 (24–29), Ta 37 (32–43); leg II: Tr 31 (29–34), Fe 44 (39–46), Ge 23 (21–24), Ti 25 (21–23), Ta 34 (35–41); leg III: Tr 39 (35–53), Fe 59 (42–55), Ge 25 (24–26), Ti 23 (23–26), Ta 49 (39–54); and leg IV: Tr 56 (37–52), Fe 66 (53–64), Ge 31 (25–29), Ti 28 (26–31), Ta 59 (58–61). Figure 36. View largeDownload slide Dytiscacarus thermonecti sp. nov. (female). Dorsal aspects of legs I–IV. A, leg I. B, leg II. C, leg III. D, leg IV. Figure 36. View largeDownload slide Dytiscacarus thermonecti sp. nov. (female). Dorsal aspects of legs I–IV. A, leg I. B, leg II. C, leg III. D, leg IV. Leg I 153 (123–164) (Fig. 36A): Tarsus: setae (ft) thin, seta ft” 6 (5–6) coupled with solenidion ω and as long as ft’ 7 (6–6), setae tc’ 15 (9–14) and tc” 12 (8–13), solenidion ω 13 (13–13) baculiform; tibia: seta v’ 27 (18–26) much longer than (l) and v” 6 (5–7), seta d 53 (68–79) attenuated, whip like, longer than other leg setae; genu: d 13 (9–15) and v’ 34 (21–33) longer than other genual setae, (l) subequal; femur: d 61 (63–68) attenuated, longer than other femoral setae, v” 36 (29–39) longer than (l); and trochanter: v 20 (24–26) shorter than length of segment. Leg II 147 (136–153) (Fig. 36B): Tarsus: setae tc’ 19 (18–21) and tc” 19 (17–18) subequal, attenuated, longer than setae (pv), solenidion ω 14 (16–16) baculiform, longer than tarsus I solenidion; tibia: v’ 21 (19–30) and v” 11 (5–10) shorter than attenuated, whip-like seta d 58 (47–82), which is longer than other leg setae; genu: d 13 (8–14) shorter than v’ 29 (21–27); femur: d 54 (61–64) attenuated, longer than other femoral setae, v” 37 (34–42) attenuated, longer than subequal (l); and trochanter: v 28 (21–26) shorter than length of segment. Leg III 184 (160–200) (Fig. 36C): Tarsus: setae tc’ 18 (15–18) and tc” 23 (14–24) subequal, attenuated, longer than setae (pv); tibia: setae v’ 14 (12–16) and v” 13 (9–9) longer than (l), seta d 68 (74–92) attenuated, whip like, longer than other leg setae; genu: v’ 8 (10–12) shorter than length of segment; femur: d 21 (21–29) longer than genual seta v’; and trochanter: v 19 (19–21) shorter than length of segment. Leg IV 253 (195–222) (Fig. 36D): Tarsus: setae tc’ 17 (15–18) and tc” 24 (18–21) attenuated, longer than setae (pv); tibia: setae v’ 16 (10–13) and v” 16 (13–15) shorter than attenuated, whip-like seta d 99 (90–108), which is the longest of all leg setae; genu: v’ 12 (9–12) shorter than length of segment; femur: d 19 (16–23) longer than tibial v”; and trochanter: v 25 (19–23) shorter than length of segment. Male (Figs 37–39) Shorter than adult female. Gnathosoma (Figs 37, 38): Length of gnathosoma 53, width 52. Length of stylets 72; pharynx length 25 and width 11; infracapitulum with setae m 11, interval between their bases 11; palpi 16, femorogenu with setae dFe 4 blunt, shorter than dGe 8; tibiotarsus with seta sul 5 blunt, shorter than blunt acm 5, seta ul’ 9 characteristically bent, longer than blunt ul” 5. Figure 37. View largeDownload slide Dytiscacarus thermonecti sp. nov. (male). Dorsal habitus, without leg setation. Figure 37. View largeDownload slide Dytiscacarus thermonecti sp. nov. (male). Dorsal habitus, without leg setation. Figure 38. View largeDownload slide Dytiscacarus thermonecti sp. nov. (male). Ventral habitus, without leg setation. Figure 38. View largeDownload slide Dytiscacarus thermonecti sp. nov. (male). Ventral habitus, without leg setation. Idiosoma: Length of idiosoma 316, width 253. Idiosomatic dorsum (Fig. 37) with length of PrsCDE 216, width 233, with microsetae vi and d, other setae except e subequal, seta e shorter than other PrsCDE setae; posterior margin of plate PrsCDE entire, not incised, with soft cuticle medially between setae d. Inner platelets F 26 long and 8 wide, ellipsoid, weakly sclerotized, each with one microseta; outer platelets F 5 long and 5 wide, rounded, weakly sclerotized, with one pair of microsetae. Genital capsule 75 long and 83 wide, subquadrate, with four pairs of microsetae, interval between ps1 bases longer than that between h1 bases, length of aedeagus 95, length of claspers 52. All dorsal plates and genital capsule with tiny dimples. Lengths of setae: ve 18, sci 19, sce 17, c1 17, c2 20 and e 3; intervals between setae: vi–vi 19, ve–ve 82, sci–sci 75, vi–ve 32, vi–sci 59, sci–ve 44, sce–sce 191, c1–c1 88, c2–c2 205, c1–sce 71, c1–c2 61, c2–sce 47, d–d 53, e–e 139, d–e 39, h1–h1 29, h2–h2 53, h3–h3 65, h1–h2 21, h1–h3 39, h2–h3 19, ps1–ps1 58 and h3–ps1 47. Idiosomatic venter (Fig. 38): apodemes 1 well developed, not reaching to slightly longer apodemes 2; sejugal apodeme weakly developed laterally; apodemes 3 and 4 well developed but not connected medially; coxal fields 1–4 with tiny dimples, all ventral setae stiff, seta 1c microseta. Lengths of setae: 1a 6, 1b 6, 2a 7, 2b 7, 3a 7, 3b 9, 3c 5 and 4a 5; intervals between setae: 1a–1b 42, 1b–1c 42, 1a–1c 33, 1a–2a 41, 2a–2b 24, 3a–3a 27, 3b–3c 38, 3c–4a 49 and 3b–4a 72. Legs (Fig. 39): Legs I thicker than others; all legs subequal in length. Lengths of leg segments are as follows: leg I: Tr 38, Fe 32, Ge 16, Ti 19, Ta 22; leg II: Tr 37, Fe 37, Ge 14, Ti 14, Ta 25; leg III: Tr 34, Fe 32, Ge 15, Ti 16, Ta 26; and leg IV: Tr 33, Fe 39, Ge 16, Ti 16, Ta 22. Figure 39. View largeDownload slide Dytiscacarus thermonecti sp. nov. (male). Dorsal aspects of legs I–IV. A, leg I. B, leg II. C, leg III. D, leg IV. Figure 39. View largeDownload slide Dytiscacarus thermonecti sp. nov. (male). Dorsal aspects of legs I–IV. A, leg I. B, leg II. C, leg III. D, leg IV. Leg I 126 (Fig. 39A): Tarsus: setae tc’ 15 and tc” 12 stiff, blunt, setae (ft) microsetae, (a) and (p) blunt, seta ft” close to baculiform solenidion ω 20, setae (a) subequal, interval between setae (pv) bases 5; tibia: all tibial setae microsetae; genu: all genual setae microsetae; femur: d and v” 18 longer than other femoral setae, l’ longer than l”; and trochanter: v 6 tiny, blunt. Leg II 113 (Fig. 39B): Tarsus: setae tc’ 15 and tc” 12 subequal, attenuated, (u) blunt, (p) pointed, solenidion ω 22 baculiform, longer than tarsus I solenidion, interval between bases of setae (pv) 5 greater than length of seta v” on tibia; tibia: l’ and v” microseta, d 17 attenuated, whip like, seta v’ minute; genu: d microseta, seta v’ 5 stiff, blunt; femur: d 22 shorter than segment, v” 11 longer than small, blunt (l); and trochanter: blunt seta v 5, small. Leg III 126 (Fig. 39C): Tarsus: setae tc’ 13 and tc” 13 subeqaul, both attenuated, as long as setae (pv), (u) blunt, (p) shorter than (tc), interval between bases of setae (pv) 6 greater than length of seta v’ on genu; tibia: v’ 6 and v” 5 blunt, stiff, subequal, shorter than attenuated, whip-like seta d 43, setae (l) minute, blunt; genu: v’ 5 blunt; femur: d 15 longer than seta v’ on genu; and trochanter: seta v 8 blunt, stiff. Leg IV 121 (Fig. 39D): Tarsus: setae tc’ 20 and tc” 13 attenuated, longer than setae (pv), (u) blunt, interval between bases of setae (pv) 5 shorter than length of seta v’ on tibia; tibia: (v) 7 blunt, stiff, shorter than attenuated, whip-like seta d 58, which is the longest of all leg setae, (l) minute; genu: v’ microseta; femur: d 12 longer than seta v” on tibia; and trochanter: blunt seta v 5 shorter than v on Tr III. Deutonymph (Figs 40–42) Gnathosoma (Figs 40, 41): Length of gnathosoma 57 (61–68), width 63 (59–64); stylets 87 (82–87) long; pharynx 32 (26–37) long and 11 (12–13) wide; infracapitulum with setae m 10 (11–13), interval between their bases 9 (9–10). Palpi 18 (12–20), femorogenu with setae and dGe 9 (8–11), twice as long as blunt dFe 4 (4–4); tibiotarsus with seta sul 5 (4–6) blunt, shorter than blunt acm 7 (5–7), seta ul’ 9 (10–11) characteristically bent, longer than blunt ul” 6 (4–6). Figure 40. View largeDownload slide Dytiscacarus thermonecti sp. nov. (deutonymph). Dorsal habitus, without leg setation. Figure 40. View largeDownload slide Dytiscacarus thermonecti sp. nov. (deutonymph). Dorsal habitus, without leg setation. Figure 41. View largeDownload slide Dytiscacarus thermonecti sp. nov. (deutonymph). Ventral habitus, without leg setation. Figure 41. View largeDownload slide Dytiscacarus thermonecti sp. nov. (deutonymph). Ventral habitus, without leg setation. Idiosoma: Length of idiosoma 469 (379–512), width 405 (274–424). Idiosomatic dorsum (Fig. 40): PrsC with central plate 242 (236–255) long and 176 (163–175) wide, club shaped, with vi microseta, seta sci longer than ve; each lateral plate 151 (147–164) long and 135 (121–132) wide, kidney shaped, setae sce, c1, c2 subequal. Tergite DE 66 (67–93) long and 225 (237–247) wide, ellipsoid, d microsetae, e longer than d. Tergite F 49 (42–51) long and 158 (153–173) wide, ellipsoid, thinner than other tergites, with two pairs of microsetae; Tergite H 56 (51–69) long and 128 (128–156) wide, ellipsoid, with three pairs of microsetae, interval between h1 bases longer than that between h2. All dorsal plates with tiny dimples. Lengths of setae: ve 16 (18–19), sci 21 (20–26), sce 16 (15–21), c1 18 (20–21), c2 20 (18–22) and e 5 (6–7); intervals between setae: vi–vi 18 (21–30), ve–ve 112 (107–107), sci–sci 89 (75–82), vi–ve 59 (53–58), vi–sci 97 (90–100), sci–ve 58 (54–62), c1–sce 92 (94–101), c1–c2 67 (75–82), c2–sce 61 (56–62), d–d 49 (51–71), e–e 173 (183–193), d–e 61 (54–67), f1–f1 79 (45–67), f2–f2 138 (105–118), f1–f2 35 (29–36), h1–h1 102 (63–84), h2–h2 94 (69–95), h3–h3 82 (72–97), h1–h2 8 (16–20), h1–h3 21 (23–29) and h2–h3 15 (8–13). Idiosomatic venter (Fig. 41): apodemes 1 well developed, not reaching to slightly shorter apodemes 2; sejugal apodeme weakly developed laterally; apodemes 3 and 4 well formed but not connected medially; coxal fields 1–4 with tiny dimples and blunt setae. Anal region with two pairs of setae ad1 and ps3 (ps3 invisible); flanked laterally by minute, blunt setae ps1 and ps2. Lengths of setae: 1a 13 (10–12), 1b 13 (7–12), 1c 8 (4–10), 2a 8 (9–11), 2b 8 (10–11), 3a 10 (8–10), 3b 15 (12–14), 3c 10 (10–11), 4a 15 (10–12), ps1 8 (6–7) and ps2 7 (5–7); intervals between setae: 1a–1b 38 (38–40), 1b–1c 33 (35–41), 1a–1c 33 (35–36), 1a–2a 49 (46–51), 2a–2b 21 (25–29), 3b–3c 41 (38–43), 3c–4a 64 (59–67) and 3b–4a 94 (87–93). Legs (Fig. 42): Lengths of leg segments are as follows: leg I: Tr 32 (28–35), Fe 37 (31–37), Ge 16 (16–17), Ti 15 (15–18), Ta 26 (23–26); leg II: Tr 37 (29–36), Fe 34 (29–38), Ge 16 (14–16), Ti 16 (13–16), Ta 24 (21–30); leg III: Tr 40 (37–45), Fe 29 (31–34), Ge 13 (15–17), Ti 19 (14–21), Ta 28 (24–33); and leg IV: Tr 45 (43–55), Fe 33 (32–41), Ge 17 (15–18), Ti 20 (15–21), Ta 27 (27–34). Figure 42. View largeDownload slide Dytiscacarus thermonecti sp. nov. (deutonymph). Dorsal aspects of legs I–IV. A, leg I. B, leg II. C, leg III. D, leg IV. Figure 42. View largeDownload slide Dytiscacarus thermonecti sp. nov. (deutonymph). Dorsal aspects of legs I–IV. A, leg I. B, leg II. C, leg III. D, leg IV. Leg I 119 (105–113) (Fig. 42A): Tarsus: setae ft’ 5 (5–7) and ft” 5 (3–5) thin, minute, ft” very close to solenidion ω, tc’ 18 (14–19) and tc” 18 (15–16) longer than other tarsal setae, solenidion ω 16 (15–16) baculiform, setae (pv) attenuated, interval between their bases 6 (7–8); tibia: v’ 12 (9–13) and v” 5 (6–6), l’ longer than blunt l”, seta d 63 (61–71) attenuated, whip like, longer than other leg setae; genu: d 22 (12–17) and l’ longer than other genual setae, v’ 7 (8–11) blunt, as long as l”; femur: d 56 (53–66) attenuated, longer than other femoral setae, v” 18 (16–19), longer than blunt setae (l), l” blunt, shorter than l’; and trochanter: blunt v 13 (9–11) shorter than seta v” on femur. Leg II 121 (99–111) (Fig. 42B): Tarsus: setae tc’ 22 (15–19) and tc” 16 (18–19), attenuated, longer than setae (pv), solenidion ω 18 (18–18) baculiform, longer than tarsus I solenidion, interval between setae (pv) bases 6 (7–8) shorter than genual seta d; tibia: seta v’ 12 (13–16) and blunt v” 6 (6–7) shorter than attenuated, whip-like seta d 67 (63–67), which is longer than other leg setae, seta l’ longer than blunt l”; genu: d 11 (12–13) and v’ 13 (11–15) subequal; femur: d 58 (50–58) attenuated, longer than other femoral setae, v” 21 (18–21) longer than blunt l’, seta l” shorter than other femoral setae; and trochanter: v 11 (12–14) shorter than length of segment. Leg III 127 (104–122) (Fig. 42C): Tarsus: setae tc’ 19 (17–22) longer than tc” 16 (14–21), both attenuated, tc’ longer than setae (pv), interval between setae (pv) bases 5 (5–7) shorter than tibial seta v”; tibia: v’ 11 (8–16) longer than blunt v” 9 (8–9), attenuated, whip-like d 71 (76–84) longer than other leg setae, l’ longer than blunt l”; genu: blunt seta v’ 7 (9–10) shorter than length of segment; femur: d 26 (21–28) longer than tarsal setae (tc); and trochanter: v 12 (9–13) as long as seta v on Tr II. Leg IV 138 (117–134) (Fig. 42D): Tarsus: setae tc’ 21 (16–21) and tc” 19 (19–23), both attenuated, longer than setae (pv), interval between setae (pv) bases 5 (2–5); tibia: v’ 11 (8–11) and v” 11 (8–9) blunt, shorter than attenuated, whip-like seta d 84 (74–100), which is the longest of all leg setae, l’ longer than blunt l”; genu: blunt v’ 7 (7–9) shorter than tibial seta v”; femur: d 16 (11–17) longer than trochanter seta v; and trochanter: v 13 (12–16) shorter than length of segment. Protonymph (Figs 43–45) Gnathosoma (Figs 43, 44): Length of gnathosoma 50 (46), width 56 (57); stylets 77 (74) long; pharynx 25 (25) long and 9 (9) wide; infracapitulum with setae m 11 (12), interval between their bases 7 (9). Palpi 17 (18), femorogenu with setae dGe 5 (4) longer than blunt dFe 3 (3); tibiotarsus with seta sul 5 (4) blunt, as long as blunt acm 5 (6), seta ul’ 8 (7) characteristically bent, longer than blunt ul” 5 (5). Figure 43. View largeDownload slide Dytiscacarus thermonecti sp. nov. (protonymph). Dorsal habitus, without leg setation. Figure 43. View largeDownload slide Dytiscacarus thermonecti sp. nov. (protonymph). Dorsal habitus, without leg setation. Figure 44. View largeDownload slide Dytiscacarus thermonecti sp. nov. (protonymph). Ventral habitus, without leg setation. Figure 44. View largeDownload slide Dytiscacarus thermonecti sp. nov. (protonymph). Ventral habitus, without leg setation. Figure 45. View largeDownload slide Dytiscacarus thermonecti sp. nov. (protonymph). Dorsal aspects of legs I–IV. A, leg I. B, leg II. C, leg III. D, leg IV. Figure 45. View largeDownload slide Dytiscacarus thermonecti sp. nov. (protonymph). Dorsal aspects of legs I–IV. A, leg I. B, leg II. C, leg III. D, leg IV. Idiosoma: Length of idiosoma 321 (334), width 265 (272). Idiosomatic dorsum (Fig. 43): PrsC with central plate 184 (187) long and 147 (150) wide, club shaped, with vi microseta, seta sci longer than ve; each lateral plate 116 (116) long and 89 (91) wide, c1 and c2 subequal. Tergite DE 47 (53) long and 173 (184) wide, ellipsoid, with two pairs of microsetae. Tergite F 57 (42) long and 40 (63) wide, ellipsoid, divided in two, with two pairs of microsetae. Tergite H 37 (33) long and 47 (46) wide, divided, with three pairs of microsetae. All dorsal plates with tiny dimples. Lengths of setae: ve 11 (11), sci 14 (12), sce 14 (9), c1 11 (10) and c2 9 (12); intervals between setae: vi–vi 34 (29), ve–ve 97 (104), sci–sci 76 (79), vi–ve 44 (49), vi–sci 82 (81), sci–ve 46 (45), c1–sce 69 (72), c1–c2 55 (66), c2– sce 47 (51), d–d 45 (48), e–e 135 (140), d–e 44 (48), f1–f2 24 (26), h1–h2 15 (13), h1–h3 27 (25) and h2–h3 13 (13). Idiosomatic venter (Fig. 44): apodemes 1 moderately developed, not reaching to similarly developed apodemes 2; sejugal apodeme weakly developed laterally; apodemes 3 and 4 weakly developed; coxal fields 1–4 with tiny dimples and blunt setae, setae 1c and 3c vestigial, setae 2a, 2b, 3a, 3b and 4a minute, stiff. Anal region without setae. Lengths of setae: 1a 6 (6), 1b 6 (6), 2a 5 (4), 2b 4 (3), 3a 6 (5), 3b 6 (7) and 4a 6 (5); intervals between setae: 1a–1b 27 (31), 1b–1c 32 (32), 1a–1c 20 (26), 1a–2a 41 (43), 2a–2b 36 (18), 3b–3c 45 (36), 3c–4a 43 (39) and 3b–4a 53 (58). Legs (Fig. 45): Lengths of leg segments are as follows: leg I: Tr 29 (33), Fe 24 (21), Ge 11 (10), Ti 13 (18), Ta 19 (17); leg II: Tr 29 (30), Fe 25 (20), Ge 13 (10), Ti 12 (18), Ta 22 (18); leg III: Tr 37 (20), Fe 21 (14), Ge 15 (10), Ti 15 (11), Ta 16 (20); and leg IV: Tr 27 (31), Fe 18 (18), Ge 11 (11), Ti 11 (9), Ta 19 (20). Leg I 92 (82) (Fig. 45A): Tarsus: setae ft’ 3 (2) and ft” m (6) thin, minute, ft” very close to solenidion ω, tc’ 15 (16) and tc” 14 (15) blunt, longer than setae (pv), solenidion ω 15 (15) baculiform, setae (pv) attenuated, interval between their bases 7 (5); tibia: v’ 7 (5) blunt, longer than blunt l’, seta v” 4 (3) blunt, longer than l”, seta d 35 (45) attenuated, whip like, longer than other leg setae; genu: minute d m (4), microsetae (l), seta v’ 3 (3) blunt; femur: d 16 (19) attenuated, longer than other femoral setae, v” 12 (8) longer than (l), microseta l”; and trochanter: vestigial v. Leg II 96 (73) (Fig. 45B): Tarsus: setae tc’ 11 (9) and tc” 9 (12) attenuated, shorter than baculiform solenidion ω 16 (17), interval between seta (pv) bases 7 (5) as long as tibial seta v’; tibia: v’ 7 (7) longer than v” 4 (3), attenuated, whip-like d 30 (37) longer than other leg setae, (l) minute; genu: d microsetae, seta l’ m (7) minute; femur: d 12 (17) attenuated, longer than other femoral setae, v” 6 (7) longer than setae (l), l” microseta; and trochanter: vestigial v. Leg III 96 (72) (Fig. 45C): Tarsus: seta tc’ 15 (14) longer than tc” 12 (8), both attenuated, interval between setae (pv) bases 5 (5); tibia: v’ 8 (5) and v” 5 (5) blunt, shorter than attenuated, whip-like seta d 32 (32), which is longer than other leg setae, (l) minute; genu: v’ 2 (6) blunt; femur: d 3 (4) blunt; and trochanter: vestigial v. Leg IV 92 (79) (Fig. 45D): Tarsus: setae tc’ 12 (9) and tc” 12 (11) subequal, attenuated, as long as setae (pv), interval between setae (vs) bases 7 (9); tibia: v’ 6 (3) and v” 5 (5) subequal, longer than minute (l), seta d 26 (29) attenuated, whip like, longest of all leg setae; genu: without seta; femur: d microseta; and trochanter: vestigial v. Larva (Fig. 46) The microscopic slide preparation is of poor quality, and some characters are vague, therefore not measurable. Gnathosoma: Stylets 57 long; pharynx 25 long and 7 wide, infracapitulum with setae m 10, interval between their bases 7. Palpi femorogenu with blunt setae dFe 4 and dGe 5; tibiotarsus with blunt setae sul 5 and acm 8, seta ul’ 11 characteristically bent, longer than blunt ul” 6. Idiosoma: Length of idiosoma 359, width 280. Idiosomatic dorsum (Fig. 46A): PrsC with central plate 174 long and 142 wide, club shaped, with vi microseta, seta sci longer than ve; each lateral plate 118 long and 76 wide, kidney shaped, sce longer than c2, seta c1 microseta. Tergite DE 63 long and 76 wide, ellipsoid, divided, with two pairs of microsetae. Tergite F 29 long and 46 wide, ellipsoid, divided, with two pairs of microsetae. Tergite H absent, microsetae h1 on striated cuticle, h2 and h3 invisible. All dorsal plates with tiny dimples; all setae blunt. Lengths of setae: ve 57 (7–8), sci 8, sce 4 and c2 5; intervals between setae: vi–vi 16, ve–ve 101, sci–sci 77, vi–ve 49, vi–sci 71, sci–ve 37, c1–sce 58, c1–c2 47, c2– sce 42, d–d 31 and f1–f2 20. Figure 46. View largeDownload slide Dytiscacarus thermonecti sp. nov. (larva). A, idiosoma, dorsal view. B, idiosoma, ventral view. C–E, dorsal aspects of tibia and tarsus, legs I–III. C, leg I. D, leg II. E, leg III. Figure 46. View largeDownload slide Dytiscacarus thermonecti sp. nov. (larva). A, idiosoma, dorsal view. B, idiosoma, ventral view. C–E, dorsal aspects of tibia and tarsus, legs I–III. C, leg I. D, leg II. E, leg III. Idiosomatic venter (Fig. 46B): apodemes 1 moderately developed, not reaching to similarly developed apodemes 2; sejugal apodemes and apodemes 3 not developed; coxal fields 1 with subequal setae 1a 3 and 1b 3, interval between 1a and 1b 18; coxal fields 3 with seta 3a 3 as long as 1a; all ventral setae blunt; anal region without setae. Legs (Fig. 46C–E): Leg I (Fig. 46C): Tarsus: setae ft’ 3 and ft” 5 minute, ft” close to solenidion ω, subequal setae (tc) 11 as long as baculiform solenidion ω 12, setae (pv) attenuated, interval between their bases 6; tibia: subequal, blunt (v) 3 longer than minute (l), seta d 32 attenuated, whip like, longer than other leg setae; genu, femur and trochanter: not measurable. Leg II (Fig. 46D): Tarsus: setae tc’ 12 and tc” 11, attenuated, as long as (pv), solenidion ω 13 baculiform, longer than tibial setae (v), interval between setae (pv) bases 6 longer than tibial seta v”; tibia: subequal v’ and blunt v” 5 longer than (l), seta d 37 attenuated, whip like, longer than other leg setae; genu, femur and trochanter: not measurable. Leg III (Fig. 46E): Tarsus: setae tc’ 16 and tc” 13 attenuated, longer than (pv), interval between setae (pv) bases 7 longer than tibial setae (v); tibia: subequal, blunt setae (v) 4 shorter than attenuated, whip-like seta d 29, which is longer than other leg setae, l’ microseta; genu, femur and trochanter: not measurable. Differential diagnosis See differential diagnoses for the previous two species. Type material All specimens collected from under elytra of six beetles of Thermonectus basilaris basilaris (Harris) from the following localities in Florida, USA. Holotype: Female, detached from under elytra of T. b. basilaris (Harris, 1829) (Insecta: Coleoptera: Dytiscidae: Dytiscinae: Aciliini) from blacklight trap on sand pine scrub, 9 miles SSW Ocala, Marion County, FL, USA, 10 September 1975, collected by J. Wiley, deposited in the CNCI, Science and Technology Branch, Agriculture and Agri-Food Canada, Ottawa, ON, Canada. Paratypes: Four deutonymphs and one larva, with the same collection data as the holotype. One female, one male, three deutonymphs and two protonymphs, ex T. b. basilaris from mesic hammock, Marion County, N end of Heather Is., 8 August 1975, coll. P. C. Drummond & J. R. Wiley. Two females, ex T. b. basilaris at blacklight trap #3 on mesic hammock, Marion County, N end of Heather Is., 11 July 1975, coll. P. C. Drummond & J. R. Wiley. Two females, ex T. b. basilaris at blacklight trap #2 on mesic hammock, Marion County, N end of Heather Is., 27 August 1975, coll. P. C. Drummond & J. R. Wiley. One female, one male and one protonymph, ex T. b. basilaris at blacklight trap, Dade County, Miami Plant Intercept Station, 6–8 April 1962, coll. D. H. Alexander. One female and one larva, ex T. b. basilaris at blacklight trap, Alachua County, 2 miles N Gainesville on hwy 441, Cypress Dome, 7 May 1974, coll. W. Jetter. One female and two deutonymphs deposited in the Acarological Collection, Department of Entomology, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran. The rest of the paratypes are retained with the holotype. Individual beetles from which mites were removed were not available for denoting as hosts. Etymology The specific epithet refers to generic name of the host beetle, Thermonectus. Classification Classification of these mites as a group in the supercohort Eleutherengonides sensuWalter et al. (2009) (or the hierarchically and conceptually equivalent infraorder Eleutherengona of Zhang et al., 2011) is based on both its exclusion from other lineages of trombidiform mites and emphatically on the presence of specialized attributes that are apomorphic to that category. In having a well-developed tracheal system with a pair of stigmata in the area of the cheliceral bases in the gnathosoma, and in lacking any indication of a caudal bend in the idiosoma, this group clearly belongs in the trombidiform suborder Prostigmata. The group is excluded from the supercohorts Labidostomatides, Eupodides and Anystides (or equivalent infraorders Labidostommatina, Eupodina and Anystina) in not having chelicerae with separate, developed bases nor having developed or remnant fixed digits apposed to non-retractable movable digits. It is further excluded in lacking larval urstigmata and postlarval genital papillae (acetabula), and having only two nymphal instars, which lack some postlarval caudal somal additions (e.g. absence of anal and peranal setae). Instead, the group is readily accommodated in the more derivative supercohort Eleutherengonides (infraorder Eleutherengona) in having cheliceral structures lacking fixed cheliceral digits and with retractable stylet-like movable digits, and in lacking larval urstigmata, postlarval genital papillae and female ovipositor. Placement of this group in either of the two cohorts (hyporders) composing the Eleutherengonides is somewhat more contentious. The presence of a series of dorsal opisthosomatic plates (tergites) on all instars, linear palpi lacking a palpal thumb-claw process, and pronounced sexual dimorphism, with males having a well-developed genital capsule, are attributes shared with the cohort Heterostigmatina. However, autapomorphic attributes ‘key’ to heterostigmatans are absent: adult females (and other instars) lack a pair of neostigmata (or heterostigmata) anterolaterally on the prodorsum; immatures and adults lack a stylophore formed by the cheliceral bases and housing the cheliceral stylets atop the infracapitulum; the pretarsus of legs II–IV lacks a smooth, pliable empodium between the bases of the paired claws; and the paired claws themselves are modified into enlarged tenent-like structures. Also, heterostigmatan females generally have a pair of prodorsal setae modified as capitate bothridial setae; however, these would not be expected to persist in mites whose entire life history occurs in a tightly enclosed space. The group is more readily accommodated in the cohort Raphignathina in sharing several attributes, discussed below; however, it is not referable to four of the five superfamilies constituting this cohort. It is excluded from the Myobioidea, a superfamily of mites exclusively ectoparasitic on mammals, which is defined apomorphically by having the chelicerae and infracapitulum fused into a gnathosomatic capsule that is retractile within the idiosoma, the female anal opening and male genito-anal opening dorsal, legs I modified for grasping hairs, and the immature instars with femora and genua fused on all legs. The new taxon is excluded from the Pterygosomatoidea, consisting of one family of mites ectoparasitic on reptiles or arthropods, and questionably belonging among the raphignathines (Sidorchuk, Perrichot & Lindquist, 2016). Pterygosomatidae is defined by mostly plesiomorphic attributes, including retention of independently movable cheliceral bases with hook-like, non-retractable, movable cheliceral digits, peritremes freely emergent dorsally from the bases of the chelicerae, five-segmented palpi with a well-developed thumb-claw process, and a full ontogenetic sequence, including three nymphal instars having an alternating calyptostasy reminiscent of the Parasitengona. A variety of reductive attributes of pterygosomatid mites persuaded Bochkov & OConnor (2006) and Bochkov et al. (2008) to suggest what Mironov & Bochkov (2009) term ‘indubitable close relations’ between Pterygosomatidae and ‘higher’ Eleutherengona. However, those attributes are all subject to homoplasy, and the cladogram of Bochkov et al. (2008) presents an unresolved trichotomy showing Pterygosomatoidea bracketed with Tetranychoidea and Myobioidea in the ‘lower Raphignatha’. The new group is immediately excluded from the Tetranychoidea, a superfamily of obligately phytophagous mites, which is defined autapomorphically by having the cheliceral bases fused into a movable stylophore that is deeply retractable into the idiosoma and contains elongated, whip-like movable cheliceral stylets recurved basally within the stylophore. Tetranychoids also differ in retaining a variably formed empodial structure between the paired claws of all legs, and the aedeagus of males is not housed in any form of genital capsule. In lacking a cheliceral stylophore with shallowly retractable cheliceral stylets, the new taxon is readily excluded from the Cheyletoidea, with its seven families of mites including arthropod associates, free-living predators often in vertebrate nests, and ecto- and endo-parasites of nesting reptiles, birds and mammals. Cheyletoids also differ, apomorphically, in greater reduction of setation of the genua and tibiae of all legs to three or fewer setae (despite setal reductions, the tibia of all legs retains five setae, and genu I has four setae in the new taxon) and in secondarily lacking a pair of gnathosomatic neostigmata, and plesiomorphically in retaining paired, claw-like claws on tarsi II and usually on tarsi III–IV, unless the legs are reduced or absent (the claws are highly modified on all legs of the new taxon). In contrast, the new taxon presents sufficient morphological similarities to the Raphignathoidea to warrant its consideration as derived or originating from within that superfamily. However, current systematic relationships among the 11 recognized raphignathoid families are so poorly understood, with its members displaying such diversity in morphological attributes and ways of life, that the superfamily as a whole is not readily definable apomorphically, and not at all autapomorphically. Moreover, the following brief family-by-family review of constituent raphignathoid families eliminates nearly all of them as immediate sister-group contenders for the new taxon. Unlike all other families of Raphignathoidea, all instars of the new taxon lack empodial structures between the bases of the paired claws of all legs. This apomorphic loss is perhaps correlated with the elaborated development of the claw structures instead (see section on leg tarsal structures, above). Unlike Cryptognathidae, the new taxon lacks the autapomorphic attribute of having the entire gnathosoma retractable into the propodosoma. Unlike the new taxon, Barbutiidae mites retain far less derivative cheliceral structures, with short, pointed, non-retractable digits on cheliceral bases that are fused only proximally, where they have short chambered peritremes. Unlike the new taxon, the Stigmaeidae, Homocaligidae, Eupalopsellidae and Mecognathidae are defined apomorphically by the absence of any gnathosomatic stigmata and associated peritremes (perhaps an argument for regarding them as composing a separate superfamily). In contrast, immatures and adults of the new taxon have a contiguous pair of tracheal trunks that emerge from intercheliceral stigmata and lead to a pair of neostigmata that open on the dorsal face of the infracapitulum, an autapomorphic attribute approached otherwise only among the following raphignathoid families. In Camerobiidae, Caligonellidae, Dasythyreidae and Xenocaligonellididae, an adjacent pair of intercheliceral stigmata within the proximal gnathosomatic base give rise to a pair of tracheal trunks that converge anteromedially, lead midway into the stylophore, where they rise dorsomedially to the dorsal stylophore surface; there, they open as a pair of contiguous neostigmata at the apex of a loop of chambered peritremes. The peritremes extend posteriorly along the stylophore surface in parallel or symmetrically convoluted patterns, often curving to the posterolateral surfaces, where they end on the anterolateral shoulders of the proterosoma, separate from the well-developed podocephalic canal system, (see figs 5A–C of Grandjean, 1946). In the new taxon, the anterodorsal extension of prostigmatic tracheal trunks is similar, but as there is only a stylophore remnant, the trunks open into the neostigmata, without forming peritremes, on the partly exposed dorsal face of the infracapitulum. Apart from gnathosomatic attributes, in immatures and adults of the new taxon, the prodorsal shield (or shields) is at least somewhat coalesced with the anteriormost shield (or shields) of the opisthosoma, such that prodorsal and tergital D setal elements are together on the same plate (or plates; see next section on sister relationships). A similar configuration occurs in Raphignathidae (Smith Meyer & Ueckermann, 1989; Kethley, 1990), more vaguely so in some Caligonellidae, and in a less similar form among a few Cheyletidae. Although the tarsi of legs I–IV lack any empodial structure in the new taxon, the paired claws somewhat resemble those of the monogeneric family Barbutiidae in having two pairs of tenent-like structures. However, these structures are probably derived independently, as they are remarkably strongly formed, sclerotized hooks in the new taxon, compared with the finer ‘tenent hair’ structure of barbutiids, which is also found among some other raphignathine taxa (e.g. Tetranychoidea). The new taxon is autapomorphic to all known raphignathine groups in three aspects that are characteristic of all active instars: a pair of neostigmata opens directly onto the dorsal surface of the infracapitulum, in the absence of a well-formed stylophore; the movable cheliceral stylets are sheathed and deeply, independently retractable into the prosoma, free from remnants of fixed cheliceral stylets; and the pretarsi of all legs lack an empodium and have the symmetrically paired claws strongly modified into sclerotized hook- and tenent-like structures. Additionally, adults are uniquely dimorphic, with the male having a caudal copulatory capsule (of different structure than among more derivative heterostigmatans) and the female having the fourth pair of legs elongated. However, do those attributes argue for recognition of a separate superfamily, or can the new taxon be argued perhaps to derive from the Raphignathoidea? These alternatives are addressed below. Dytiscacaridae and sister relationships As discussed above, morphological aspects of the gnathosoma, dorsal idiosoma and leg tarsi of Dytiscacarus are so uniquely specialized that it is difficult to relate the taxon to those of other families among the Raphignathina. Hence, one option is to place the group in its own superfamily as well as family, and leave it unplaced among other superfamilies of Raphignathina, or even as its own cohort (or hyporder) level at the base of the raphignathine and heterstigmatine lineages. However, this would imply an ancientness of derivation that is not supported by evidence from the dytiscid beetle hosts. The age of the eleutherengone lineage split between raphignathines and heterostigmatines should pre-date the association of early-derivative heterocheylid mites with passalid beetles. Passalidae is one of the more ancient families of scarabaeoid beetles, with a fossil record dating back to Lower Jurassic times, and indications of the mite–beetle association dating back to the mid-Jurassic, some 175 Mya (Lindquist, 1996). In contrast, based on current knowledge and fossil calibration points, the dytiscid beetle lineage goes back only to the mid-Cretaceous, ~110 Mya, such that the dytiscacaroid mite–dytiscid beetle association is not nearly as deep in time (Bukontaite, Miller & Bergsten, 2014). In searching for shared, significant morphological similarities between Dytiscacarus and other taxa of both Raphignathina and Heterostigmatina, one salient aspect is evident: the larvae and nymphs of Dytiscacarus and Raphignathus have the prodorsal sclerotization integrated to some extent with that of opisthosomatic tergite C, and uniquely configured to present an obovate anteromedial dorsal plate situated between a pair of lateral plates. Each lateral plate bears setal elements of the prodorsum and somite C, such that at least one of the two prodorsal scapular setae (sce) and one of the two tergite C setae (c2) are together on the lateral plates (Figs 10A, 13A, 16A, 25, 28, 31, 40, 43, 46A; see also sigla notation applied to adult female Raphignathus by Smith Meyer & Ueckermann, 1989, fig. 162, and Kethley, 1990, fig. 180). To some extent, this argument is based on interpretation of setal homologies (see somewhat disparate notation by Kethley, 1990, figs 180 vs. 183). However, if a different interpretation of homologies is applied, such that the posteromedial pair of setae on the anteromedial plate are c1 instead of sci, then the lateral plates still bear both prodorsal (sci, sce) and somite C (c2) setae. Any other configuration of dorsal setae (e.g. Atyeo, 1963) would also place some opisthodorsal somite setae on those anteromedial and lateral plates. This configuration of anterior plates with setae is not clearly found elsewhere among eleutherengone mites. Pursuing similarities between Dytiscacarus and Raphignathus, a trend towards more expansive dorsal idiosomatic sclerotization is found among females of some species of Raphignathus. Those of Raphignathus hirtellus Athias-Henriot, 1961 and Raphignathus neocardinalis Atyeo, 1963 exceed the condition in Dytiscacarus in having all setae of the d, e, f, h series on an expansive dorsal opisthosomatic plate, whereas those of some other species have a less expansive plate, such that setae d or d and e are on striated soft cuticle. However, the adult female condition in all cases, unlike Dytiscacarus, retains a soft cuticle strip separating the anterior plates from the opisthsomatic plate. In contrast, males of Raphignathus have the anterior three plates consolidated into one, which bears all v, sc and c setae. That anterior plate may be separate or partly integrated with an expansive opisthosomatic plate bearing setae of the D, E and F somites (Atyeo, 1963; Smith Meyer & Ueckermann, 1989). If partly integrated, the two plates are separated laterally by soft cuticular incisions reminiscent of those on male Dytiscacarus. Among eleutherengones without evidence of idiosomatic hypertrichy, a symplesiomorphy of Dytiscacarus and Raphignathus is retention of three pairs of h setae flanking the three pairs of pseudanal setae. The presence of a third pair of setae, h3, on somite H is unusual among superfamilies of Eleutherengona. However, this setal complement is readily evident beginning with the larval instar, and is found on larvae and subsequent instars of less derivative taxa of Trombidiformes, such as Anystidae (Grandjean, 1943), and is included in the basic pattern for acariform mites by Grandjean (1939). Although some authors (e.g. Smith Meyer & Ueckermann, 1989; Fan & Zhang, 2005) have recognized the presence of h1–h3 among raphignathids, others are discordant (e.g. Kethley, 1990 denoted h2 as f2 on the female, and h1 as f1 on the male; Atyeo, 1963 presented similarly discordant notation using different sigla). A general pattern of larval idiosomatic setation in Raphignathus has not been stated in the literature; however, the larvae of two undetermined species at hand [one being Raphignathus near gracilis (Rack)], have only two pairs of h setae, with nymphal addition of a third pair of setae (E.E.L., personal observations). One larva (near gracilis) also has only two pairs of ps setae, whereas the other has three pairs. The larva of several species of African Raphignathus were noted to have only two pairs of h setae, but the numbers of ps setae were not clarified (Smith Meyer & Ueckermann, 1989). In both Raphignathus and Dytiscacarus, the cheliceral bases are fully fused mesally to form a stylophore, which, although appressed, is not fused with the infracapitulum. The stylophore itself is not retractile within the proterosoma, despite the stylets themselves being deeply so in Dytiscacarus. Although similar in integrated form and lacking a median septum, the stylophore of Dytiscacarus is so much reduced in size, relative to that of Raphignathus, that it no longer functions as a stylophore. In both genera, a pair of dorsal neostigmata arise via paired contiguous tracheal trunks from intercheliceral stigmata (sensuGrandjean, 1938) at the base of the stylophore. The neostigmata open on a basal fissure of the stylophore in Raphignathus, whereas they extend under the abbreviated stylophore and open on the exposed dorsal face of the infracapitulum at the apical edge of the stylophore in Dytiscacarus. In both genera, the neostigmata are not associated with peritremes embedded into the dorsal surface of the stylophore, as in Caligonellidae. Both Raphignathus and Dytiscacarus are characterized by a derivative form of slender, nearly straight, at least somewhat elongated cheliceral stylets attached to short, inconspicuous basal levers. All active instars of Raphignathus have slender, slightly retractable stylets, which in some species are more remarkably elongated. For example, the stylet lengths of R. near cometes Atyeo (60–65 μm) exceed the entire gnathosomatic capsule length (~50 μm; E.E.L., personal observations, noting that stylet lengths are somewhat shorter, ~0.75 the stylophore length in some other species). However, whereas the stylets of Raphignathus remain apical, apposed by pointed, hyaline extensions of the fixed digits projecting from the stylophore, those of Dytiscacarus lack any fixed digit remnants and are much more elongated, fully retractable and ensheathed deeply into the proterosoma, each apparently independently extrudible. Male Raphignathus and Dytiscacarus have highly elaborated copulatory structures, including a pair of strongly developed accessory structures that flank an aedeagus. The copulatory complex of male Raphignathus has never been studied in detail. Although not housed in a dimorphically specialized genital capsule, the genitalia are more strongly developed, including what appear to be paired, apically knobbed grasping structures, than in other forms of raphignathines (E.E.L., unpublished observations). Likewise, the mechanisms of male Dytiscacarus genitalia are not understood, but the genital capsule includes what appears to be a pair of movable structures, in this case with setigenous tips. The leg setation of Raphignathus and Dytiscacarus does not offer any particular sharing of attributes, other than the tibiae of all legs plesiomorphically retaining more than three setae, in distinction to the families of Cheyletoidea, which apomorphically retain three or fewer setae. The above discussion argues for some phylogenetic relationship between the essentially monogeneric family Raphignathidae (justification for recognition of the monobasic genus Neoraphignathus Smiley and Moser, 1968 is problematical) and the new monogeneric family, Dytiscacaridae. As they currently appear, mites of these two taxa differ tremendously in form and ways of life. However, the adaptation of one lineage to a parasitic way of life initiated drastic morphological changes, in contrast to the continued free-living comportment of the other. Similarly drastic morphological adaptations to symbiotic ways of life on insects are immediately evident in other such monogeneric families as Heterocheylidae on passalid beetles (Lindquist & Kethley, 1975) and Crotalomorphidae on carabid beetles (Lindquist & Krantz, 2002), in contrast to their more freely living predatory or fungivorous sister groups. Dytiscid beetles pupate on land surfaces somewhat distant from water. Whether this interval and location might have provided opportunities for putatively terrestrial progenitors of dytiscacarid mites to initiate contact and association with their hosts is highly speculative but worthy of consideration. Issues with integrating the new raphignathine taxon into published keys to families of Prostigmata Using the most prevalent key to families of Prostigmata by Walter et al. (2009), attributes of the new taxon of Raphignathina are immediately discordant at the third step, couplet 3, where one must ignore both the absence of an empodium on tarsi II–III and the presence of a male genital capsule to move another three steps to couplet 8; there, one must ignore the presence of strongly developed paired claws, usually with serrate margins, to continue another three steps to couplet 30, where one cannot effectively move forward, amidst the superfamilies and families of Raphignathina. Much as is done with couplet 2 in extracting the Labidostommatidae, a new couplet 3 inserted before the current one could extract the new taxon by the following: 3a. Adults and immatures with a pair of stigmata opening on dorsal face of subcapitulum at apical margin of fused cheliceral bases; chelicerae with long, straight, stylet-like movable digits deeply retractable into proterosoma; tarsi I–IV with strongly sclerotized lateral claws armed with retrorse basal hooks and serrated apical margins, and without an empodium; males with a genital capsule encasing strongly formed genitalia. Subelytral symbionts of dytiscid water beetles … Dytiscacaridae. 3b. Adults and immatures with a pair of stigmata various in position but not opening on dorsal face of subcapitulum at apical margin of fused cheliceral bases, or absent; chelicerae various, rarely so deeply retractable; tarsi I–IV with lateral claws variously formed other than noted above, or absent, and with empodium present or absent; sexual dimorphism strong or weak, but males without genital capsule excepting some families of Heterostigmatina … 4. Using the key to families of terrestrial endeostigmatic and prostigmatic mites by Kethley (1990), one bogs down after six steps at couplet 39, distinguishing between Cheyletoidea and Raphignathoidea. There, by ignoring the location of the base of the cheliceral digit, one may tentatively move another four steps to couplets 44, 45, where one is stymied by whether the pretarsal claws are nude or with tenent hairs, and by the nature of the cheliceral bases and associated peritremes. As this key is designed for terrestrial mites, no attempt is made to integrate a new family of mites that are subelytral symbionts of aquatic beetles into it. DISCUSSION Invertebrate parasitism in Eleutherengonides The supercohort (or infraorder) Eleutherengonides comprises two sister cohorts (or hyporders), Raphignathina and Heterostigmatina (Walter et al., 2009). Among mites of the Raphignathina, parasitism is mostly well adapted and focused on various vertebrates, whereas invertebrate parasitism is not characteristic for this lineage of the Trombidiformes (Bochkov et al. 2008; Walter et al. 2009). Table 1 lists all raphignathine species with evident or apparent parasitic ways of life on invertebrates. The host taxa are confined to Arachnida (scorpion families Buthidae, Vaejovidae, Caraboctonidae and Superstitioniidae) and Insecta. The insect hosts are distributed in Blattodea (Blaberidae, Blattellidae and Blattidae), Coleoptera (Carabidae, Dermestidae, Elateridae and Tenebrionidae), Diptera (Psychodidae) and Hemiptera (Reduviidae). The mite taxa are included in three superfamilies, Pterygosomatoidea (Pterygosomatidae), Raphignathoidea (Stigmaeidae) and Cheyletoidea (Cheyletidae). Table 1. Invertebrate parasitic mites of the Raphignathina Mite taxon Superfamily Family Genus and species Host Source Pterygosomatoidea Pterygosomatidae Pimeliaphilus andersoni Newell & Ryckman, 1966 Triatoma gerstaeckeri (Stål, 1859), Triatoma recurva (Stål, 1868) (Hemiptera: Reduviidae) Newell & Ryckman (1966), Anderson (1968) Pimeliaphilus buysi Olivier, 1977 Physosterna sp., Stips dohrni (Haag-Rutenberg, 1872) (Coleoptera: Tenebrionidae) Olivier (1977) Pimeliaphilus calimesae Newell and Ryckman, 1966 Triatoma protracta (Uhler, 1894) (Hemiptera: Reduviidae) Newell & Ryckman (1966) Pimeliaphilus cunliffei Jack, 1961 Periplaneta americana (L., 1758), Blatta orientalis L., 1758 (Blattodea: Blattidae); Blattella germanica (L., 1767) (Blattodea: Blattellidae) Field, et al.(1966), Newell & Ryckman (1966) Pimeliaphilus desertus Olivier, 1977 Anthia thoracica (Thunberg, 1784) (Coleoptera: Carabidae) Olivier (1977) Pimeliaphilus gloriosus Newell and Ryckman, 1966 Triatoma barberi Usinger, 1939 (Hemiptera: Reduviidae) Newell & Ryckman (1966) Pimeliaphilus isometri Cunliffe, 1949 Isometrus sp. (Scorpiones: Buthidae) Cunliffe (1949) Pimeliaphilus joshuae Newell and Ryckman, 1966 Triatoma rubida (Uhler, 1894) (Hemiptera: Reduviidae); Androctonus australis (L., 1758), Androctonus amoreuxi (Audouin, 1826), Leiurus quinquestriatus (Ehrenberg, 1828), Centruroides sculpturatus Ewing, 1928 (Scorpiones: Buthidae); Vaejovis confusus Stahnke, 1940, Vaejovis spinigerus (Wood, 1863), Smeringurus mesaensis (Stahnke, 1957), Smeringurus vachoni (Stahnke, 1961) (Scorpiones: Vaejovidae); Hadrurus arizonensis (Ewing, 1928) (Scorpiones: Caraboctonidae); Superstitionia donensis Stahnke, 1940 (Scorpiones: Superstitioniidae) Berkenkamp & Landers (1983), Ibrahim & Abdel-Rahman (2011) Pimeliaphilus peninsularis Newell and Ryckman, 1966 Triatoma peninsularis Usinger, 1940 (Hemiptera: Reduviidae) Newell & Ryckman (1966) Pimeliaphilus penrithi Olivier, 1977 Derocalymma sp. (Blattodea: Blaberidae) Olivier (1977) Pimeliaphilus plumifer Newell and Ryckman, 1966 Triatoma protracta, Triatoma rubida (Uhler, 1894), Triatoma recurva, Paratriatoma hirsuta Barber, 1938, Meccus pallidipennis (Stål, 1872), Meccus bassolsae (Alejandre Aguilar et al., 1999), Meccus longipennis (Usinger, 1939), Meccus picturatus (Usinger, 1939) (Hemiptera: Reduviidae) Newell & Ryckman (1966), Anderson (1968), Zumaquero et al. (2004), Martinez-Sanchez et al. (2007) Pimeliaphilus podapolipophagus Trägårdh, 1905 Pimelia sp. (Coleoptera: Tenebrionidae), undetermined cockroach (Blattodea) Trägårdh (1905), Cunliffe (1952), Newell & Ryckman (1966), Hoffmann & López-Campos (2000) Pimeliaphilus rapax Beer, 1960 Vaejovis punctatus Karsch, 1879, Vaejovis nitidulus C. L. Koch, 1842, Vaejovis intrepidus Thorell, 1876 (Scorpiones: Vaejovidae) Beer (1960) Hoffmann & López-Campos (2000), Pimeliaphilus sanguisugae Newell and Ryckman, 1966 Triatoma sanguisuga (Leconte, 1855) (Hemiptera: Reduviidae) Newell & Ryckman (1966) Pimeliaphilus triatomae Cunliffe, 1952 Triatoma infestans (Klug, 1834), Triatoma sp., Meccus pallidipenis (Hemiptera: Reduviidae) Cunliffe (1952), Newell & Ryckman (1966), Hoffmann & López-Campos (2000), Zumaquero et al. (2004) Pimeliaphilus trogadermus Cunliffe, 1968 Trogoderma variabile Ballion, 1878 (Coleoptera: Dermestidae) Cunliffe (1968) Pimeliaphilus zeledoni Newell and Ryckman, 1969 Triatoma dimidiata (Latreille, 1811) (Hemiptera: Reduviidae) Newell & Ryckman (1969) Calderón-Arguedas (1998), Pimeliaphilus sp. Phlebotomus alexandri Sinton, 1928 (Diptera: Psychodidae) Lewis & Macfarlane (1981) Raphignathoidea Stigmaeidae Eustigmaeus dyemkoumai (Abonnenc, 1970) Phlebotomus duboscqi Neveu-Lemaire, 1906 (Diptera: Psychodidae) Abonnenc (1970), Lewis & Macfarlane (1981) Eustigmaeus gamma (Chaudhri, 1965) Phlebotomus pius Fairchild and Hertig, 1961 (Diptera: Psychodidae) Chaudhri (1965), Lewis & Macfarlane (1981) Eustigmaeus gorgasi (Chaudhri, 1965) Phlebotomus pius, Phlebotomus sp. (Diptera: Psychodidae) Chaudhri (1965); Lewis & Macfarlane (1981) Eustigmaeus johnstoni Zhang and Gerson, 1995 Phlebotomus longicuspis Nitzulescu, 1930, Phlebotomus papatasi (Scopoli, 1786), Sergentomyia africana (Newstead, 1912), Sergentomyia dreyfussi (Parrot, 1933), Sergentomyia magna (Sinton, 1932); Phlebotomus bergeroti Parrot, 1934, Phlebotomus sergenti Parrot, 1917 (Diptera: Psychodidae) Zhang & Gerson (1995); Shehata and Baker (1996); Ozbel et al. (1999); Badakhshan et al. (2013) Eustigmaeus lirella (Summers and Price, 1961) Lutzomyia apache (Young and Perkins, 1984) (Diptera: Psychodidae) Reeves et al. (2008) Eustigmaeus parasiticus (Chaudhri, 1965) Phlebotomus sp., Lutzomyia gomezi (Nitzulescu, 1931) (Diptera: Psychodidae) Chaudhri (1965); Lewis & Macfarlane (1981) Stigmaeus sinai Swift, 1987 Phlebotomus papatasi (Diptera: Psychodidae) Swift (1987) Stigmaeus smithi (Mitra and Mitra, 1953) Phlebotomus papatasi (Diptera: Psychodidae) Mitra & Mitra (1953) Stigmaeus youngi (Hirst, 1926) Phlebotomus martini Parrot, 1936, Phlebotomus duboscqi, Phlebotomus papatasi, Phlebotomus sergenti, Phlebotomus argentipes Annandale and Brunetti, 1908, Sergentomyia spp. (Diptera: Psychodidae) Hirst (1926); Wood (1972); Lewis & Macfarlane (1981) Cheyletoidea Cheyletidae Pavlovskicheyla platydemae Thewke and Enns, 1975 Platydema ruficornis (Stürm, 1826) (Coleoptera: Tenebrionidae) Thewke & Enns (1975); Bochkov & Otto (2010) Mite taxon Superfamily Family Genus and species Host Source Pterygosomatoidea Pterygosomatidae Pimeliaphilus andersoni Newell & Ryckman, 1966 Triatoma gerstaeckeri (Stål, 1859), Triatoma recurva (Stål, 1868) (Hemiptera: Reduviidae) Newell & Ryckman (1966), Anderson (1968) Pimeliaphilus buysi Olivier, 1977 Physosterna sp., Stips dohrni (Haag-Rutenberg, 1872) (Coleoptera: Tenebrionidae) Olivier (1977) Pimeliaphilus calimesae Newell and Ryckman, 1966 Triatoma protracta (Uhler, 1894) (Hemiptera: Reduviidae) Newell & Ryckman (1966) Pimeliaphilus cunliffei Jack, 1961 Periplaneta americana (L., 1758), Blatta orientalis L., 1758 (Blattodea: Blattidae); Blattella germanica (L., 1767) (Blattodea: Blattellidae) Field, et al.(1966), Newell & Ryckman (1966) Pimeliaphilus desertus Olivier, 1977 Anthia thoracica (Thunberg, 1784) (Coleoptera: Carabidae) Olivier (1977) Pimeliaphilus gloriosus Newell and Ryckman, 1966 Triatoma barberi Usinger, 1939 (Hemiptera: Reduviidae) Newell & Ryckman (1966) Pimeliaphilus isometri Cunliffe, 1949 Isometrus sp. (Scorpiones: Buthidae) Cunliffe (1949) Pimeliaphilus joshuae Newell and Ryckman, 1966 Triatoma rubida (Uhler, 1894) (Hemiptera: Reduviidae); Androctonus australis (L., 1758), Androctonus amoreuxi (Audouin, 1826), Leiurus quinquestriatus (Ehrenberg, 1828), Centruroides sculpturatus Ewing, 1928 (Scorpiones: Buthidae); Vaejovis confusus Stahnke, 1940, Vaejovis spinigerus (Wood, 1863), Smeringurus mesaensis (Stahnke, 1957), Smeringurus vachoni (Stahnke, 1961) (Scorpiones: Vaejovidae); Hadrurus arizonensis (Ewing, 1928) (Scorpiones: Caraboctonidae); Superstitionia donensis Stahnke, 1940 (Scorpiones: Superstitioniidae) Berkenkamp & Landers (1983), Ibrahim & Abdel-Rahman (2011) Pimeliaphilus peninsularis Newell and Ryckman, 1966 Triatoma peninsularis Usinger, 1940 (Hemiptera: Reduviidae) Newell & Ryckman (1966) Pimeliaphilus penrithi Olivier, 1977 Derocalymma sp. (Blattodea: Blaberidae) Olivier (1977) Pimeliaphilus plumifer Newell and Ryckman, 1966 Triatoma protracta, Triatoma rubida (Uhler, 1894), Triatoma recurva, Paratriatoma hirsuta Barber, 1938, Meccus pallidipennis (Stål, 1872), Meccus bassolsae (Alejandre Aguilar et al., 1999), Meccus longipennis (Usinger, 1939), Meccus picturatus (Usinger, 1939) (Hemiptera: Reduviidae) Newell & Ryckman (1966), Anderson (1968), Zumaquero et al. (2004), Martinez-Sanchez et al. (2007) Pimeliaphilus podapolipophagus Trägårdh, 1905 Pimelia sp. (Coleoptera: Tenebrionidae), undetermined cockroach (Blattodea) Trägårdh (1905), Cunliffe (1952), Newell & Ryckman (1966), Hoffmann & López-Campos (2000) Pimeliaphilus rapax Beer, 1960 Vaejovis punctatus Karsch, 1879, Vaejovis nitidulus C. L. Koch, 1842, Vaejovis intrepidus Thorell, 1876 (Scorpiones: Vaejovidae) Beer (1960) Hoffmann & López-Campos (2000), Pimeliaphilus sanguisugae Newell and Ryckman, 1966 Triatoma sanguisuga (Leconte, 1855) (Hemiptera: Reduviidae) Newell & Ryckman (1966) Pimeliaphilus triatomae Cunliffe, 1952 Triatoma infestans (Klug, 1834), Triatoma sp., Meccus pallidipenis (Hemiptera: Reduviidae) Cunliffe (1952), Newell & Ryckman (1966), Hoffmann & López-Campos (2000), Zumaquero et al. (2004) Pimeliaphilus trogadermus Cunliffe, 1968 Trogoderma variabile Ballion, 1878 (Coleoptera: Dermestidae) Cunliffe (1968) Pimeliaphilus zeledoni Newell and Ryckman, 1969 Triatoma dimidiata (Latreille, 1811) (Hemiptera: Reduviidae) Newell & Ryckman (1969) Calderón-Arguedas (1998), Pimeliaphilus sp. Phlebotomus alexandri Sinton, 1928 (Diptera: Psychodidae) Lewis & Macfarlane (1981) Raphignathoidea Stigmaeidae Eustigmaeus dyemkoumai (Abonnenc, 1970) Phlebotomus duboscqi Neveu-Lemaire, 1906 (Diptera: Psychodidae) Abonnenc (1970), Lewis & Macfarlane (1981) Eustigmaeus gamma (Chaudhri, 1965) Phlebotomus pius Fairchild and Hertig, 1961 (Diptera: Psychodidae) Chaudhri (1965), Lewis & Macfarlane (1981) Eustigmaeus gorgasi (Chaudhri, 1965) Phlebotomus pius, Phlebotomus sp. (Diptera: Psychodidae) Chaudhri (1965); Lewis & Macfarlane (1981) Eustigmaeus johnstoni Zhang and Gerson, 1995 Phlebotomus longicuspis Nitzulescu, 1930, Phlebotomus papatasi (Scopoli, 1786), Sergentomyia africana (Newstead, 1912), Sergentomyia dreyfussi (Parrot, 1933), Sergentomyia magna (Sinton, 1932); Phlebotomus bergeroti Parrot, 1934, Phlebotomus sergenti Parrot, 1917 (Diptera: Psychodidae) Zhang & Gerson (1995); Shehata and Baker (1996); Ozbel et al. (1999); Badakhshan et al. (2013) Eustigmaeus lirella (Summers and Price, 1961) Lutzomyia apache (Young and Perkins, 1984) (Diptera: Psychodidae) Reeves et al. (2008) Eustigmaeus parasiticus (Chaudhri, 1965) Phlebotomus sp., Lutzomyia gomezi (Nitzulescu, 1931) (Diptera: Psychodidae) Chaudhri (1965); Lewis & Macfarlane (1981) Stigmaeus sinai Swift, 1987 Phlebotomus papatasi (Diptera: Psychodidae) Swift (1987) Stigmaeus smithi (Mitra and Mitra, 1953) Phlebotomus papatasi (Diptera: Psychodidae) Mitra & Mitra (1953) Stigmaeus youngi (Hirst, 1926) Phlebotomus martini Parrot, 1936, Phlebotomus duboscqi, Phlebotomus papatasi, Phlebotomus sergenti, Phlebotomus argentipes Annandale and Brunetti, 1908, Sergentomyia spp. (Diptera: Psychodidae) Hirst (1926); Wood (1972); Lewis & Macfarlane (1981) Cheyletoidea Cheyletidae Pavlovskicheyla platydemae Thewke and Enns, 1975 Platydema ruficornis (Stürm, 1826) (Coleoptera: Tenebrionidae) Thewke & Enns (1975); Bochkov & Otto (2010) View Large Table 1. Invertebrate parasitic mites of the Raphignathina Mite taxon Superfamily Family Genus and species Host Source Pterygosomatoidea Pterygosomatidae Pimeliaphilus andersoni Newell & Ryckman, 1966 Triatoma gerstaeckeri (Stål, 1859), Triatoma recurva (Stål, 1868) (Hemiptera: Reduviidae) Newell & Ryckman (1966), Anderson (1968) Pimeliaphilus buysi Olivier, 1977 Physosterna sp., Stips dohrni (Haag-Rutenberg, 1872) (Coleoptera: Tenebrionidae) Olivier (1977) Pimeliaphilus calimesae Newell and Ryckman, 1966 Triatoma protracta (Uhler, 1894) (Hemiptera: Reduviidae) Newell & Ryckman (1966) Pimeliaphilus cunliffei Jack, 1961 Periplaneta americana (L., 1758), Blatta orientalis L., 1758 (Blattodea: Blattidae); Blattella germanica (L., 1767) (Blattodea: Blattellidae) Field, et al.(1966), Newell & Ryckman (1966) Pimeliaphilus desertus Olivier, 1977 Anthia thoracica (Thunberg, 1784) (Coleoptera: Carabidae) Olivier (1977) Pimeliaphilus gloriosus Newell and Ryckman, 1966 Triatoma barberi Usinger, 1939 (Hemiptera: Reduviidae) Newell & Ryckman (1966) Pimeliaphilus isometri Cunliffe, 1949 Isometrus sp. (Scorpiones: Buthidae) Cunliffe (1949) Pimeliaphilus joshuae Newell and Ryckman, 1966 Triatoma rubida (Uhler, 1894) (Hemiptera: Reduviidae); Androctonus australis (L., 1758), Androctonus amoreuxi (Audouin, 1826), Leiurus quinquestriatus (Ehrenberg, 1828), Centruroides sculpturatus Ewing, 1928 (Scorpiones: Buthidae); Vaejovis confusus Stahnke, 1940, Vaejovis spinigerus (Wood, 1863), Smeringurus mesaensis (Stahnke, 1957), Smeringurus vachoni (Stahnke, 1961) (Scorpiones: Vaejovidae); Hadrurus arizonensis (Ewing, 1928) (Scorpiones: Caraboctonidae); Superstitionia donensis Stahnke, 1940 (Scorpiones: Superstitioniidae) Berkenkamp & Landers (1983), Ibrahim & Abdel-Rahman (2011) Pimeliaphilus peninsularis Newell and Ryckman, 1966 Triatoma peninsularis Usinger, 1940 (Hemiptera: Reduviidae) Newell & Ryckman (1966) Pimeliaphilus penrithi Olivier, 1977 Derocalymma sp. (Blattodea: Blaberidae) Olivier (1977) Pimeliaphilus plumifer Newell and Ryckman, 1966 Triatoma protracta, Triatoma rubida (Uhler, 1894), Triatoma recurva, Paratriatoma hirsuta Barber, 1938, Meccus pallidipennis (Stål, 1872), Meccus bassolsae (Alejandre Aguilar et al., 1999), Meccus longipennis (Usinger, 1939), Meccus picturatus (Usinger, 1939) (Hemiptera: Reduviidae) Newell & Ryckman (1966), Anderson (1968), Zumaquero et al. (2004), Martinez-Sanchez et al. (2007) Pimeliaphilus podapolipophagus Trägårdh, 1905 Pimelia sp. (Coleoptera: Tenebrionidae), undetermined cockroach (Blattodea) Trägårdh (1905), Cunliffe (1952), Newell & Ryckman (1966), Hoffmann & López-Campos (2000) Pimeliaphilus rapax Beer, 1960 Vaejovis punctatus Karsch, 1879, Vaejovis nitidulus C. L. Koch, 1842, Vaejovis intrepidus Thorell, 1876 (Scorpiones: Vaejovidae) Beer (1960) Hoffmann & López-Campos (2000), Pimeliaphilus sanguisugae Newell and Ryckman, 1966 Triatoma sanguisuga (Leconte, 1855) (Hemiptera: Reduviidae) Newell & Ryckman (1966) Pimeliaphilus triatomae Cunliffe, 1952 Triatoma infestans (Klug, 1834), Triatoma sp., Meccus pallidipenis (Hemiptera: Reduviidae) Cunliffe (1952), Newell & Ryckman (1966), Hoffmann & López-Campos (2000), Zumaquero et al. (2004) Pimeliaphilus trogadermus Cunliffe, 1968 Trogoderma variabile Ballion, 1878 (Coleoptera: Dermestidae) Cunliffe (1968) Pimeliaphilus zeledoni Newell and Ryckman, 1969 Triatoma dimidiata (Latreille, 1811) (Hemiptera: Reduviidae) Newell & Ryckman (1969) Calderón-Arguedas (1998), Pimeliaphilus sp. Phlebotomus alexandri Sinton, 1928 (Diptera: Psychodidae) Lewis & Macfarlane (1981) Raphignathoidea Stigmaeidae Eustigmaeus dyemkoumai (Abonnenc, 1970) Phlebotomus duboscqi Neveu-Lemaire, 1906 (Diptera: Psychodidae) Abonnenc (1970), Lewis & Macfarlane (1981) Eustigmaeus gamma (Chaudhri, 1965) Phlebotomus pius Fairchild and Hertig, 1961 (Diptera: Psychodidae) Chaudhri (1965), Lewis & Macfarlane (1981) Eustigmaeus gorgasi (Chaudhri, 1965) Phlebotomus pius, Phlebotomus sp. (Diptera: Psychodidae) Chaudhri (1965); Lewis & Macfarlane (1981) Eustigmaeus johnstoni Zhang and Gerson, 1995 Phlebotomus longicuspis Nitzulescu, 1930, Phlebotomus papatasi (Scopoli, 1786), Sergentomyia africana (Newstead, 1912), Sergentomyia dreyfussi (Parrot, 1933), Sergentomyia magna (Sinton, 1932); Phlebotomus bergeroti Parrot, 1934, Phlebotomus sergenti Parrot, 1917 (Diptera: Psychodidae) Zhang & Gerson (1995); Shehata and Baker (1996); Ozbel et al. (1999); Badakhshan et al. (2013) Eustigmaeus lirella (Summers and Price, 1961) Lutzomyia apache (Young and Perkins, 1984) (Diptera: Psychodidae) Reeves et al. (2008) Eustigmaeus parasiticus (Chaudhri, 1965) Phlebotomus sp., Lutzomyia gomezi (Nitzulescu, 1931) (Diptera: Psychodidae) Chaudhri (1965); Lewis & Macfarlane (1981) Stigmaeus sinai Swift, 1987 Phlebotomus papatasi (Diptera: Psychodidae) Swift (1987) Stigmaeus smithi (Mitra and Mitra, 1953) Phlebotomus papatasi (Diptera: Psychodidae) Mitra & Mitra (1953) Stigmaeus youngi (Hirst, 1926) Phlebotomus martini Parrot, 1936, Phlebotomus duboscqi, Phlebotomus papatasi, Phlebotomus sergenti, Phlebotomus argentipes Annandale and Brunetti, 1908, Sergentomyia spp. (Diptera: Psychodidae) Hirst (1926); Wood (1972); Lewis & Macfarlane (1981) Cheyletoidea Cheyletidae Pavlovskicheyla platydemae Thewke and Enns, 1975 Platydema ruficornis (Stürm, 1826) (Coleoptera: Tenebrionidae) Thewke & Enns (1975); Bochkov & Otto (2010) Mite taxon Superfamily Family Genus and species Host Source Pterygosomatoidea Pterygosomatidae Pimeliaphilus andersoni Newell & Ryckman, 1966 Triatoma gerstaeckeri (Stål, 1859), Triatoma recurva (Stål, 1868) (Hemiptera: Reduviidae) Newell & Ryckman (1966), Anderson (1968) Pimeliaphilus buysi Olivier, 1977 Physosterna sp., Stips dohrni (Haag-Rutenberg, 1872) (Coleoptera: Tenebrionidae) Olivier (1977) Pimeliaphilus calimesae Newell and Ryckman, 1966 Triatoma protracta (Uhler, 1894) (Hemiptera: Reduviidae) Newell & Ryckman (1966) Pimeliaphilus cunliffei Jack, 1961 Periplaneta americana (L., 1758), Blatta orientalis L., 1758 (Blattodea: Blattidae); Blattella germanica (L., 1767) (Blattodea: Blattellidae) Field, et al.(1966), Newell & Ryckman (1966) Pimeliaphilus desertus Olivier, 1977 Anthia thoracica (Thunberg, 1784) (Coleoptera: Carabidae) Olivier (1977) Pimeliaphilus gloriosus Newell and Ryckman, 1966 Triatoma barberi Usinger, 1939 (Hemiptera: Reduviidae) Newell & Ryckman (1966) Pimeliaphilus isometri Cunliffe, 1949 Isometrus sp. (Scorpiones: Buthidae) Cunliffe (1949) Pimeliaphilus joshuae Newell and Ryckman, 1966 Triatoma rubida (Uhler, 1894) (Hemiptera: Reduviidae); Androctonus australis (L., 1758), Androctonus amoreuxi (Audouin, 1826), Leiurus quinquestriatus (Ehrenberg, 1828), Centruroides sculpturatus Ewing, 1928 (Scorpiones: Buthidae); Vaejovis confusus Stahnke, 1940, Vaejovis spinigerus (Wood, 1863), Smeringurus mesaensis (Stahnke, 1957), Smeringurus vachoni (Stahnke, 1961) (Scorpiones: Vaejovidae); Hadrurus arizonensis (Ewing, 1928) (Scorpiones: Caraboctonidae); Superstitionia donensis Stahnke, 1940 (Scorpiones: Superstitioniidae) Berkenkamp & Landers (1983), Ibrahim & Abdel-Rahman (2011) Pimeliaphilus peninsularis Newell and Ryckman, 1966 Triatoma peninsularis Usinger, 1940 (Hemiptera: Reduviidae) Newell & Ryckman (1966) Pimeliaphilus penrithi Olivier, 1977 Derocalymma sp. (Blattodea: Blaberidae) Olivier (1977) Pimeliaphilus plumifer Newell and Ryckman, 1966 Triatoma protracta, Triatoma rubida (Uhler, 1894), Triatoma recurva, Paratriatoma hirsuta Barber, 1938, Meccus pallidipennis (Stål, 1872), Meccus bassolsae (Alejandre Aguilar et al., 1999), Meccus longipennis (Usinger, 1939), Meccus picturatus (Usinger, 1939) (Hemiptera: Reduviidae) Newell & Ryckman (1966), Anderson (1968), Zumaquero et al. (2004), Martinez-Sanchez et al. (2007) Pimeliaphilus podapolipophagus Trägårdh, 1905 Pimelia sp. (Coleoptera: Tenebrionidae), undetermined cockroach (Blattodea) Trägårdh (1905), Cunliffe (1952), Newell & Ryckman (1966), Hoffmann & López-Campos (2000) Pimeliaphilus rapax Beer, 1960 Vaejovis punctatus Karsch, 1879, Vaejovis nitidulus C. L. Koch, 1842, Vaejovis intrepidus Thorell, 1876 (Scorpiones: Vaejovidae) Beer (1960) Hoffmann & López-Campos (2000), Pimeliaphilus sanguisugae Newell and Ryckman, 1966 Triatoma sanguisuga (Leconte, 1855) (Hemiptera: Reduviidae) Newell & Ryckman (1966) Pimeliaphilus triatomae Cunliffe, 1952 Triatoma infestans (Klug, 1834), Triatoma sp., Meccus pallidipenis (Hemiptera: Reduviidae) Cunliffe (1952), Newell & Ryckman (1966), Hoffmann & López-Campos (2000), Zumaquero et al. (2004) Pimeliaphilus trogadermus Cunliffe, 1968 Trogoderma variabile Ballion, 1878 (Coleoptera: Dermestidae) Cunliffe (1968) Pimeliaphilus zeledoni Newell and Ryckman, 1969 Triatoma dimidiata (Latreille, 1811) (Hemiptera: Reduviidae) Newell & Ryckman (1969) Calderón-Arguedas (1998), Pimeliaphilus sp. Phlebotomus alexandri Sinton, 1928 (Diptera: Psychodidae) Lewis & Macfarlane (1981) Raphignathoidea Stigmaeidae Eustigmaeus dyemkoumai (Abonnenc, 1970) Phlebotomus duboscqi Neveu-Lemaire, 1906 (Diptera: Psychodidae) Abonnenc (1970), Lewis & Macfarlane (1981) Eustigmaeus gamma (Chaudhri, 1965) Phlebotomus pius Fairchild and Hertig, 1961 (Diptera: Psychodidae) Chaudhri (1965), Lewis & Macfarlane (1981) Eustigmaeus gorgasi (Chaudhri, 1965) Phlebotomus pius, Phlebotomus sp. (Diptera: Psychodidae) Chaudhri (1965); Lewis & Macfarlane (1981) Eustigmaeus johnstoni Zhang and Gerson, 1995 Phlebotomus longicuspis Nitzulescu, 1930, Phlebotomus papatasi (Scopoli, 1786), Sergentomyia africana (Newstead, 1912), Sergentomyia dreyfussi (Parrot, 1933), Sergentomyia magna (Sinton, 1932); Phlebotomus bergeroti Parrot, 1934, Phlebotomus sergenti Parrot, 1917 (Diptera: Psychodidae) Zhang & Gerson (1995); Shehata and Baker (1996); Ozbel et al. (1999); Badakhshan et al. (2013) Eustigmaeus lirella (Summers and Price, 1961) Lutzomyia apache (Young and Perkins, 1984) (Diptera: Psychodidae) Reeves et al. (2008) Eustigmaeus parasiticus (Chaudhri, 1965) Phlebotomus sp., Lutzomyia gomezi (Nitzulescu, 1931) (Diptera: Psychodidae) Chaudhri (1965); Lewis & Macfarlane (1981) Stigmaeus sinai Swift, 1987 Phlebotomus papatasi (Diptera: Psychodidae) Swift (1987) Stigmaeus smithi (Mitra and Mitra, 1953) Phlebotomus papatasi (Diptera: Psychodidae) Mitra & Mitra (1953) Stigmaeus youngi (Hirst, 1926) Phlebotomus martini Parrot, 1936, Phlebotomus duboscqi, Phlebotomus papatasi, Phlebotomus sergenti, Phlebotomus argentipes Annandale and Brunetti, 1908, Sergentomyia spp. (Diptera: Psychodidae) Hirst (1926); Wood (1972); Lewis & Macfarlane (1981) Cheyletoidea Cheyletidae Pavlovskicheyla platydemae Thewke and Enns, 1975 Platydema ruficornis (Stürm, 1826) (Coleoptera: Tenebrionidae) Thewke & Enns (1975); Bochkov & Otto (2010) View Large Pterygosomatoidea Members of the family Pterygosomatidae, the sole family in the superfamily, are permanent parasites of mostly vertebrates and some invertebrates (Bochkov et al., 2008). Of ten genera, eight are parasites of various lizards (one species of Geckobia is exceptional in parasitizing tortoises), one on a dove, and the last one, Pimeliaphilus, with ~20 species, is recorded from arthropods, lizards and sometimes off host, freely in soil (Paredes-Leon, Klompen & Perez, 2012). The ectoparasitic species of this genus, for which there is an arthropod host record, are summarized in Table 1. Most Pimeliaphilus species are associated with haematophagous triatomine bugs. Other hosts are four families of scorpions, three families of beetles, three families of roaches and one species of Phlebotomus flies (Diptera: Psychodidae). Ibrahim & Abdel-Rahman (2011) studied the prevalence and abundance of Pimeliaphilus joshuae on various scorpions in Egypt and concluded that this mite parasitizes a wide range of scorpions with low host specificity. Berkenkamp & Landers (1983) also mentioned the low degree of host specificity in natural populations of scorpions in central Arizona, USA. Newell & Ryckman (1966), in a comprehensive study on ten species of Pimeliaphilus, stated that the triatomine bugs were settled in habitats of the vertebrate hosts. In spite of mono- or oligoxenous pterygosomatids on lizards, species of Pimeliaphilus tend to be parasites of arthropods living in concealed habitats (Bochkov et al., 2008), not necessarily on specifically preferred hosts. Mites of this genus may have transferred from vertebrates to arthropods that live in their nests, and thereafter to other ground-dwelling arthropods. Thus, in Pterygosomatidae, lizards are considered as ancestral hosts, and parasitism of arthropods is secondary, as a result of host switching from lizards (Paredes-Leon et al., 2012), a hypothesis which is contrary to that of Bochkov & OConnor (2006). Mites of the genus Pimeliaphilus do not appear to be very specific and so can survive on another host within their range. One species may even transfer from a non-insect host (scorpion) to a triatomid bug (Berkenkamp & Landers, 1983). Raphignathoidea Most representatives of the 11 included families are free-living predators (Fan & Zhang, 2005). However, in mites of the family Stigmaeidae, six species of the genus Eustigmaeus and three species of Stigmaeus (see Table 1) are thought to parasitize blood-feeding phlebotomine sandflies (Diptera: Psychodidae). The indications for these mites being parasites are feeding scars and lesions observed on the body of the hosts. There is no direct evidence of host haemolymph in the gut systems of these mites, and their impact on the host flies has not been evaluated. Also, no males or immature mites are reported on the host; therefore, their parasitic lifestyle remains doubtful. Cheyletoidea Six of seven families of this superfamily are highly specialized ecto- and endoparasites of vertebrates, and the family Cheyletidae consists of both vertebrate parasites and free-living predators (Bochkov et al., 2008; Walter et al., 2009). Some of the free-living cheyletids have established relationships with invertebrates, mostly bees and beetles; those are restricted to phoresy (e.g. Ramaraju & Mohanasundaram, 1999; Bochkov & Klimov, 2004; Bochkov & Otto, 2010). An exceptional parasitic relationship is that of Pavlovskicheyla platydemae Thewke & Enns, all instars of which were recovered from under the elytra of a tenebrionid beetle (Thewke & Enns, 1975); however, Bochkov et al. (2008) considered this to be an unverified example of parasitism. The above review of the scarce and scattered raphignathine mites parasitizing invertebrates indicates that true parasitism of invertebrates is an unlikely evolutionary trend in this cohort. Therefore, despite support of some morphological characters to include Dytiscacaridae in Raphignathina (see systematic part of the text), it seems that the new taxon does not match ecologically with any one of the aforementioned superfamilies. In contrast, in the sister cohort Heterostigmatina, associations with invertebrates are well documented and characteristic (Kaliszewski et al., 1995; Walter et al., 2009). For some lineages, this association is confined to phoresy (e.g. fungivorous pygmephorid, scutacarid and tarsonemid mites), and for some others parasitoidism is recorded (Pyemotidae, Acarophenacidae, and a few Microdispidae and Tarsonemidae). Females of several other families (Athyreacaridae, Caraboacaridae and Resinacaridae) have close associations with insects, but the nature of their symbioses remains undetermined. Females of the family Trochometridiidae have been determined to be kleptoparasites of their bee associates. The killing of the egg or larva of the bee in the brood cells occupied allows development of fungal growth in the provisioned cells, providing food for the mites. After undergoing physogastry, they produce masses of eggs that hatch into non-feeding larvae, most of which develop into the next generation of females (Cross & Bohart, 1969, 1978). True parasitism, however, has evolved independently in the following superfamilies. Heterocheyloidea This superfamily, a relatively early derivative among heterostigmatans (Lindquist & Kethley, 1975), is represented by a monogeneric family with 25 species. All members of the family are subelytral symbionts of passalid beetles. Although no published observations on the biology of these mites have been made, a parasitic relationship has been inferred from the form of their gnathosomatic structures and from the fact that all active instars (larva, protonymph, deutonymph, adult female and male) have been repeatedly collected, albeit in fewer numbers than females, as subelytral associates of passalid beetles (Schuster & Lavoipierre, 1970). A moderately high degree of host specificity has been noted (Schuster & Lavoipierre, 1970). Dolichocyboidea Two families are assigned to this lineage, Dolichocybidae and Crotalomorphidae, with the former containing six genera and 40 species of fungivorous mites, mostly phoretic on ants and beetles living in subcortical habitats (e.g. Magowski, 1988; Hajiqanbar & Khaustov, 2010; Rahiminejad, Hajiqanbar & Fathipour, 2011; Katlav, Hajiqanbar & Talebi, 2014a; Mortazavi, Hajiqanbar & Kamali, 2015). The monobasic family Crotalomorphidae was established to accommodate parasitic engorged and gravid adult females detached from beneath elytra of the carabid genus Stenolophus. This taxon is distributed in the USA (Lindquist & Krantz, 2002; Husband & Husband, 2003; 2004; 2005). Pyemotoidea Adult females of the sister families Acarophenacidae and Pyemotidae are parasitoids primarily on the eggs and immature instars of insects of the orders Thysanoptera, Homoptera, Lepidoptera, Coleoptera, Diptera and Hymenoptera. The mite progeny usually develop and mate inside the physogastric body of the mother. The family Pyemotidae currently consists of one genus, Pyemotes, with ~25 species that are classified into two species groups, ventricosus and scolyti, based on their toxicity to the host and degree of host specificity. The ventricosus group has a wide host spectrum and occurs in many habitats. Females are extremely venomous and attack all host instars. Members of the scolyti group are restricted to their host habitats and are usually associated with bark beetles, feeding on host eggs, larvae and pupae. Females are not venomous, so do not cause dermatitis and other health problems in people and animals they contact (Kaliszewski et al., 1995; Walter et al., 2009). Acarophenacidae encompasses six extant genera and ~40 species, among which those of the genera Aethiophenax, Paracarophenax and some Acarophenax are associated with beetles of several families, such as Cerambycidae, Cucujidae, Dermestidae, Nitidulidae, Mycetophagidae, Curculionidae (subfamily Scolytinae) and Tenebrionidae (Goldarazena, Ochoa & Jordana, 1999; Walter et al., 2009; Katlav, Hajiqanbar & Talebi, 2015b; Arjomandi, Hajiqanbar & Joharchi, 2017; Walter & Seeman, 2017). All described species of the genus Adactylidium are egg parasitoids of tubuliferous thrips (Thysanoptera: Tubulifera; Goldarazena et al., 2001). Host associations of other genera are unknown. Little is known about the way of life of mites of the families Caraboacaridae and Resinacaridae, also placed in Pyemotoidea, but adult females of Caraboacarus resemble those of other pyemotoids in the form of their feeding structures, and those of Resinacarus are physogastric (Vitzthum, 1927; Walter et al., 2009). Three genera and eight species of the family Caraboacaridae have a bizarre association with a variety of carabid beetles (Eidelberg, 1993; Hajiqanbar et al., 2008; Katlav et al., 2015a). According to Cross (1965) and Nickel & Elzinga (1969), these mites are suspected to be ectoparasites of their host beetles, based on their enlarged cheliceral stylets and some biological observations of their stylets inserted into the veins of the hind-wing of their host. However, given that no male and other instars of caraboacarid mites have been recovered from their hosts, a parasitic way of life seems to be doubtful (Kaliszewski et al., 1995). Tarsonemoidea Two speciose and ubiquitous families, Tarsonemidae and Podapolipidae, are included in Tarsonemoidea. The family Tarsonemidae, with > 40 genera and 550 species, is a euryphagous lineage of heterostigmatic mites feeding on fungi, algae and plants, and some are predators or phoretics and some others parasites or parasitoids of insects (Walter et al., 2009). Parasitism has evolved in the tarsonemid subfamily Acarapinae, including two tribes Acarapini (with only the genus Acarapis) and Coreitarsonemini (with three genera: Coreitarsonemus, Amcortarsonemus and Asiocortarsonemus). All active instars of the genus Acarapis (with three recognized species) are parasites of honeybees, two of which are ectoparasites and the third, Acarapis woodi (Rennie), is a well-known endoparasite feeding on haemolymph through the tracheal walls of the host respiratory system. All active instars of the Coreitarsonemini are also endoparasitic, living in atria of the thoracic glands of the Coreidae (Insecta: Hemiptera) (Lindquist, 1986; Walter et al., 2009). All members of the family Podapolipidae, including 32 genera and > 260 species, are highly specialized obligate parasites that attack insects distributed in five orders: Coleoptera, Orthoptera, Blattodea, Hemiptera and Hymenoptera (Husband & OConnor, 2014; Katlav et al., 2014b; Husband & Husband, 2015). These mites are highly adapted to parasitic ways of life, as indicated by reductive aspects in both morphology (especially reduction in the number of legs of adult females, ranging from four pairs to zero) and ontogenetic reductions (trends towards only two active instars, and males copulating with larval females). Most hosts belong to Coleoptera, such that 23 of 32 genera parasitize ten beetle families (Hajiqanbar, 2013; Kurosa & Husband, 2013; Husband & OConnor, 2014). Many genera exhibit a degree of host specificity at the family level. For instance, the genus Coccipolipus feeds exclusively on beetles of the family Coccinellidae (Husband, 1972), and Podapolipoides prefers to parasitize grasshoppers of the family Acrididae (Hajiqanbar & Joharchi, 2011). A notable exception is Podapolipus, members of which parasitize three families of Coleoptera, some Orthoptera and a few Blattaria (Hajiqanbar, 2013). Podapolipids are primarily ectoparasites, usually living in the subelytral cavity of host beetles; however, a few taxa are endoparasites: three species of Locustacarus in the tracheal system of acridids and bumblebees, three species of Ovacarus in the genital tracts of carabid beetles, and Chrysomelobia lawsoni (Seeman & Nahrung) in the tracheae of chrysomelid beetles (Stannard & Vaishampayan, 1971; Husband, 1974; Husband & Husband, 1996; Seeman & Nahrung, 2005; Hajiqanbar et al., 2007). The aforementioned data reveal that the new taxon, to some extent, has similarity to beetle-associated representatives of such distantly related families of the cohort Heterostigmatina as the early derivative Heterocheylidae and the highly derivative Podapolipidae regarding the way of life (true parasitism of arthropods). However, morphological traits exclude the new taxon from the Heterostigmatina (see systematic part of the manuscript). Moreover, all representatives of the eleutherengonine parasitic lineages of arthropods (including Heterocheylidae and Podapolipidae) are associated with terrestrial arthropods, and no species have been found on water beetles or any other aquatic insects. Notes on aquatic beetles harbouring the new taxon of parasitic mites About 25 families in three of four suborders of Coleoptera (i.e. Myxophaga, Adephaga including Dytiscidae, and Polyphaga) are typically aquatic in some of their life stages. Beetles of the family Dytiscidae are predaceous water insects, comprising 11 subfamilies, 26 tribes, nearly 190 genera and > 4300 species (Miller & Bergsten, 2016). The oldest fossil of a Dytiscidae is of late Jurassic age (165–145 Mya; Miller & Bergsten, 2016), but a recent dating analysis of the family Dytiscidae recovered a crown age of Dytiscidae at 159 Mya and a stem age at 170 Mya (J. Bergsten, personal communication, October 2017). As dytiscacarid mites have been found on both aciliine and hydatiscine beetles, barring a more recent and highly unlikely transfer between unrelated but coexistent hosts, it may be inferred that this mite lineage dates to a period of time in the mid-Cretaceous, some 110–90 Mya, which is an estimated divergence time between the host tribes Hydaticini and Aciliini (see Fig. 47) as subsets of the family Dytiscidae (Bukontaite et al., 2014; J. Bergsten, personal communication, October 2017). Figure 47. View largeDownload slide Summary tree for subfamilies Dytiscinae (with included tribes) and Cybistrinae, adapted from Miller & Bergsten (2014b), showing dytiscine tribes hosted by dytiscacarid mites (red circles). Figure 47. View largeDownload slide Summary tree for subfamilies Dytiscinae (with included tribes) and Cybistrinae, adapted from Miller & Bergsten (2014b), showing dytiscine tribes hosted by dytiscacarid mites (red circles). Dytiscid beetles are ready fliers, and often travel and scatter some distance to reach new habitats. They generally fly in the evening or at night, and they can use reflected light from water surfaces as a method of finding new habitats (Crowson, 1981; Lawrence & Britton, 1991). Otherwise, these diving beetles spend most of their life cycle in the water (Crowson, 1981). Adult beetles usually deposit their eggs in the underwater stems of plants. Both adults and larvae are predaceous and can attack a wide range of small aquatic organisms. Dytiscids generally prefer slow-moving or stagnant water, and pools at the edges of streams. As adults need air, they rise to the surface to adsorb air, which is stored in a chamber underneath their elytra and allows them to increase the time they can be submerged. Perhaps the subelytral parasitic colony of dytiscacarid mites uses the air in this chamber for respiration, somewhat like water mites of the genus Eylais, whose parasitic larvae enter the subelytral air space of their host dytiscid beetles during replenishment of their air stores at the water surface (Aiken, 1985). This may be partly confirmed by our observations: at least two colonies (D. iranicus and D. americanus) were adhered to the inner surface of the host’s elytra, with even the mite eggs (of D. iranicus) being completely glued to that surface by a gelatinous substance. Arnold (1964) mentioned that there is a strong flow of haemolymph in the ventral leading (costal–subcostal) edge of the host beetle hind-wings, where mites (such as Eylais larvae) may have an adequate source (vein or sinus) of food. However, it is not clear whether parasitic dytiscacarid mites use their stylets to penetrate either fore- or hind-wings for nourishment. Miller & Bergsten (2014b), following morphology and DNA sequence data, recognized five tribes (Dytiscini, Hydaticini including Hydaticus, Aubehydrini, Eretini, and Aciliini including Thermonectus) and 12 genera in the subfamily Dytiscinae (Fig. 47). The genus Hydaticus Leach, 1817, with 143 recognized species, is currently classified in two subgenera, Hydaticus (Hydaticus) and Hydaticus (Prodaticus). Hydaticus s.s. includes seven known species and Hydaticus (Prodaticus) 136 species. Beetles of this genus are distributed worldwide (Fig. 48), with those of Hydaticus s. str. restricted to the Holarctic region, whereas those of H. (Prodaticus) are much more widespread, primarily found in subtropical to tropical regions, with a few extending into temperate latitudes. Species of Hydaticus are univoltine, with oviposition occurring in spring, then larvae developing in summer; adults overwinter out of the water (Nilsson & Holmen, 1995). The two Hydaticus species recorded as hosts for the mite parasitic taxa both belong to H. (Prodaticus), H. (P.) bimarginatus (Say, 1830) and H. (P.) pictus (Sharp, 1882). Based on a both morphological and molecular phylogenetic study of the tribe Hydaticini conducted by Miller et al. (2009), H. bimarginatus is more derivative than H. pictus. Hydaticus bimarginatus is distributed in Nearctic and Neotropical realms (Nilsson, 2013). With a Palaearctic and specifically Asian origin, H. pictus has been recorded from various countries of western Asia (Nilsson & Hajek, 2016). The genus Thermonectus Dejean, 1833 is the most speciose genus of the tribe Aciliini, with 19 species, existing in the Neotropics and the Nearctic north to the southern Canadian border (Fig. 49; Nilsson, 2013). Thermonectus basilaris (Harris, 1829) has almost the same distribution as the genus, specifically in Cuba, eastern USA, and north to southeastern Canada (Nilsson, 2013). With many species in the host genera Hydaticus and Thermonectus, it will be interesting to see whether the mites they harbour represent many other species or few species with wider host ranges, and whether the mites may track or indicate species–group relationships among their hosts. Figure 48. View largeDownload slide Distribution map of Hydaticus (black area) and associated Dytiscacarus (black and white stars). Figure 48. View largeDownload slide Distribution map of Hydaticus (black area) and associated Dytiscacarus (black and white stars). Figure 49. View largeDownload slide Distribution map of Thermonectus (black area) and associated Dytiscacarus (white star). Figure 49. View largeDownload slide Distribution map of Thermonectus (black area) and associated Dytiscacarus (white star). Dispersal and host transfer A rather puzzling or challenging aspect concerns how these specialized parasitic mites may transfer from one host to another. Dytiscacarid mites are likely never to be free from their adult hosts. All instars, including eggs, are confined to the subelytral space of their hosts. No instar is modified for swimming, or even crawling on aquatic substrates; instead, all active instars have the paired claws of all legs modified into a complex of retrorse hooks and adhesive expansions for attachment to their host. The more elongately developed legs of adult female Dytiscacaridae allow us to speculate that the adult female has greater mobility and may be the dispersant instar, as in many raphignathine and heterostigmatic mites. Ecologically, lineages most similar to Dytiscacaridae are the heterostigmatic families Heterocheylidae and Podapolipidae. All active instars of Heterocheylidae (larva, protonymph, deutonymph and adult) are subelytral symbionts of passalid beetles. The relationship between Heterocheylus species and passalids may involve parasitism, but this has not been confirmed (Schuster & Lavoipierre, 1970). As in most other families of heterostigmatans, adult females may be the dispersants, as they are more routinely found on the beetles. However, behavioural aspects of heterocheylids, such as mating behaviour and dispersal, have not been observed (Walter et al., 2009). In contrast, the Podapolipidae is a morphologically and ontogenetically specialized family parasitizing insects of several orders, particularly beetles. Their life history is reduced to only two active instars, larva and adult. Adult females often display bizarre reductions in numbers of legs, and adult males usually exhibit modified positions of the genital apparatus (Regenfuss, 1973; Walter et al., 2009). Most described podapolipid species are sexually transmitted parasites (Knell & Webberley, 2004; Seeman & Nahrung, 2004; Webberley et al., 2004), meaning that a mobile instar of the parasite is capable of migrating between hosts during copulation (or between parental and filial generations). This behaviour has been confirmed by several previous authors studying different kinds of podapolipids on different hosts, with details not presented here (e.g. Volkonsky, 1940; Regenfuss, 1968, 1973). Observations by Hurst et al. (1995) on Coccipolipus hippodamiae McDaniel & Morrill, parasitizing the promiscuous two-spotted ladybird, Adalia bipunctata L., indicated that larval female mites migrate during host mating. This may be the case for the majority of taxa of podapolipids; however, in species of the genus Chrysomelobia Regenfuss, 1968, the putatively most primitive genus of the Podapolipidae, the adult female is responsible for this type of transmission (Regenfuss, 1968, 1973; Seeman & Nahrung, 2004). An evolutionary pathway of reduction in the number of legs became a factor that excludes adult females of most podapolipids as the dispersant stage (Regenfuss, 1973). Host transfer by parasitic mites having all active instars attached to and developing on the same host is all the more challenging when the parasitized instar of the host lives in an entirely different manner from other instars. Other than when flying to new aquatic systems or overwintering/aestivating (in mud or pond bottom substrates, or on land), dytiscid adults are fully and freely aquatic, swimming and diving beetles. Their larvae are also fully aquatic (although not divers), with their last instar moving onto land to pupate (Larson, Alarie & Roughley, 2000). Although dytiscid larvae have not been examined for this new group of mites, it is very unlikely that they are parasitized or even carry them, in view of their entirely different form and way of life. It is likewise unlikely that the mites in their dispersal stage could freely locate and attach to last instar beetle larvae moving into substrates to pupate, and then await emergence of young adult beetles. This leaves the pairing contacts between adult beetles of the same generation, and those of parental and filial generations, as the primary (if not the only) source of host transfer. Many of these beetles mate repeatedly, and there is often intense sexual conflict, both before and after insemination. Among long-lived species, there may be some overlap of generations. Pairings occur in the water, and typically, are fairly long in large diving beetles (subfamily Dytiscinae; e.g. hours in Dytiscus spp.), allowing considerable time for possible mite transfers. Pairs surface a number of times to exchange subelytral air during such episodes (Bilton, Thompson & Foster, 2008; Miller & Bergsten, 2014a; D. T. Bilton, personal communication, October 2017). According to Knell & Webberley (2004), two attributes of many Coleoptera facilitate sexual transmission of mites: a promiscuous mating system and overwintering as adults. These aspects provide some overlapping of adult generations, which is essential for the survival of sexually transmitted parasites. As dytiscid beetles are promiscuous, overwinter as adults, and occupy a habitat that seems restrictive to dispersal, we expect that dytiscacarid mites will also be sexually transmitted. CONCLUSIONS As this study shows, morphologically highly specialized parasitic mites often pose interesting challenges in their classification, which in turn may stimulate reviews of the systematic relationships among the more free-living or otherwise symbiotically associated mites of putatively related families. It is all too easy to propose higher taxon categories for such apomorphically distinctively specialized mites; however, they must be derived from some lineage with free-living ancestors. These reviews may now have molecular analytical methods to help resolve phylogenetic relationships among families. Molecular studies may also be designed to assess the diet of particular mites (Garcia-Robledo, Staines & Kress, 2015), and thereby confirm feeding behaviour and preferences, such as phytophagy or parasitism. However, those analyses do not clarify other interesting aspects of acarine ways of life, such as dispersal, mating behaviour, host transfer and life cycle. It is noteworthy that our preliminary efforts to obtain and sequence DNA of Iranian mite material were unsuccessful. However, further collections will be continued to obtain sufficient material for sequencing DNA (see Acknowledgements). Major or otherwise extensive collections of insects also harbour a trove of mites adhering to the insects, often in locations not immediately discernible, such as under wing covers, in crevasses between the head and thorax, thorax and abdomen, spiracular cavities, intercoxal areas and genitalia. Although dry and often tens or scores of years old, adherent mites in such areas are often intact and may make fully suitable preparations for microscopic study, along with having reliable collection locality data and available host identification. Many of these adherent mites have a simply phoretic association with their insect carriers; however, others are symbiotically more specialized, some as parasites or parasitoids. Once discoveries such as the present one are made, they may be augmented by careful searches for additional material in insect collections. In this case, a limited search for further mites on additional beetles of one of the species associated with H. bimarginatus met with immediate success in the Canadian National Collection of Insects (see Acknowledgments). Such searches may also provide some indication of prevalences of the mites on their hosts, for which no data are as yet available. The present study provides strong support for our introductory statements about the diversity of the spectrum of mites parasitic on other arthropods, worldwide. Furthermore, it indicates how unexpected the new individual findings may be among vast, as yet undiscovered associations. Discovery of this association, alone, may be only the tip of an iceberg, as these morphologically highly specialized mites indicate a long history of specialized relationship with their beetle hosts in the Holarctic Region. How many other species and perhaps genera of dytiscacarid mites may there be, not only among dytiscid beetles but also perhaps among some other groups of water beetles as well? Dytiscid beetles alone comprise ~4300 species in ~190 genera and are nearly worldwide in distribution (Miller & Bergsten, 2016). In view of invertebrate parasitic mites of families such as the heterostigmatic Heterocheylidae and Podapolipidae occurring throughout most of the ranges of their insect hosts, we may anticipate a similarly extensive occurrence of dytiscacarid mites. ACKNOWLEDGEMENTS We are grateful to Anders Nilsson (University of Umeå, Sweden) for help in identifying the Iranian dytiscid host beetle. Wayne Knee (Agriculture & AgriFood Canada, Ottawa) searched for and made slide preparations available for some of the mites used in this study. We thank Pavel Klimov in the laboratory of Barry OConnor (University of Michigan, USA) for his collaboration with A.M. to extract DNA from Iranian mites. Special thanks to David T. Bilton (School of Biological and Marine Science, Faculty of Science and Engineering, Plymouth University, UK) for helpful comments on some biological and behavioural aspects of dytiscid beetles, and Johannes Bergsten (Department of Zoology, Swedish Museum of Natural History, Stockholm) for sending some literature, advice on antiquity of Dytiscidae and Fig. 47. The constructive, thorough reviews by Owen Seeman and Barry OConnor are deeply appreciated. [Version of Record, published online 29 March 2018; http://zoobank.org/urn:lsid:zoobank.org:pub:A0C8E9B5-A37B-4F2A-AB41-542C9AFCCEE4] REFERENCES Abonnenc E . 1970 . Notes sur les Acariens parasites des Phlebotomes. Cahiers L’office de la Recherche Scientifique et Technique Outer-Mer . Serie Entomologie medicale et Parasitologie 8 : 89 – 94 . Aiken RB . 1985 . Attachment sites, phenology, and growth of larvae of Eylais sp. (Acari) on Dytiscus alaskanus J. Balfour-Browne (Coleoptera: Dytiscidae) . 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A new family of mites (Acari: Prostigmata: Raphignathina), highly specialized subelytral parasites of dytiscid water beetles (Coleoptera: Dytiscidae: Dytiscinae)