Nematocysts and Taxonomy in Laomedea, Gonothyraea and Obelia (Hydrozoa, Campanulariidae)ÖSTMAN, CARINA
doi: 10.1111/j.1463-6409.1982.tb00536.xpmid: N/A
The cnidoms of Laomedea flexuosa, Gonothyraea loveni, Obelia geniculata, O. longissima and O. dichotoma were studied by light and scanning electron microscopy to find out whether the nematocysts could be used as taxonomic characters. Three b‐rhabdoid heteroneme nematocysts (microbasic b‐mastigophore) and three isorhizous haploneme nematocysts (atrichous isorhiza) were distinguished. A small b‐rhabdoid nematocyst with spindle‐shaped capsule occurred in all the species examined. In the polyp and planula of G. loveni, and the planula of L. flexuosa it was the only nematocyst present. Specific for L. flexuosa was a b‐rhabdoid with curved capsule. In the polyp and newly‐liberated medusa of O. longissima another b‐rhabdoid appeared with bean‐shaped capsule and markedly long spines at the distal tube. The polyp and newly‐liberated medusa of O. dichotoma were characterized by two different isorhizas. A special type of isorhiza occurred in the polyp of O. geniculata. The curved capsules of the different isorhizas varied somewhat in shape and size. Differences in nematocyst structure and occurrence are presumed to provide characters for taxonomy. Thus, O. dichotoma and O. Iongissima are regarded as separate species due to their distinctly different nematocysts, in conjunction with other morphological and ecological differences.
On the Identity and Nomenclature of Paracanthonchus caecus (Bastian, 1865), with a Redefinition of the Genus Paracanthonchus Micoletzky (Nematoda, Cyatholaimidae)VINCX, MAGDA; SHARMA, JYOTSNA; SMOL, NICOLE
doi: 10.1111/j.1463-6409.1982.tb00537.xpmid: N/A
A historical review of the systematics of Paracanthonchus caecus (Bastian, 1865) and a comparison of specimens from different localities show that this “species” in fact comprises four distinct species. Paracanthonchus caecus Micoletzky, 1924 nec P. caecus (Bastian, 1865) is designated as the valid type species of the genus Paracanthonchus. P. heterodontus (Schulz, 1932) and P. thaumasius (Schulz, 1932) are re‐established. P. caecm sensu Gerlach 1965 is considered as a distinct species: P. gerlachi sp.n. P. canadensis sp.n. is described and is very close to P. caecus Micoletzky, 1924. The subspecies P. caecus opthalmophorus (Steiner, 1921), different from the typical caecus by the presence of ocelli, is considered as a different species; we therefore propose P.ophthalmophorus (Steiner, 1921) stat.n. The genus Paracanthonchus is redefined.
Description of Psammodrilus aedificator sp.n. (Polychaeta), with Notes on the Arctic Interstitial Fauna of Disko Island, W. Greenland *KRISTENSEN, REINHARDT MØBJERG; NØRREVANG, ARNE
doi: 10.1111/j.1463-6409.1982.tb00538.xpmid: N/A
Psammodrilus aedificator sp.n. is described from an arctic subtidal sandy habitat at 2–3 m depth. The new species represents a link between the two genera Psammodrilus and Psammodriloides, but it has a distinct warty collar shared only with Psammodrilus balanoglossoides. This unique structure was investigated by transmission electron microscopy. Each wart consists of one large cell with microvilli arranged in a hexagonal pattern. The collar epidermis is devoid of cilia. The head consists of prostomium and peristomium, the thorax consists of 7(8) segments, both tagmata totally ciliated. Each of the six pairs of cirri have an aciculum. The abdomen consists of 20 segments and is ciliated except for the dorsal sulcus. Psammodrilus aedifcator sp.n. is sessile and forms a “house” of agglutinated sand grains. Only females (8 mm) and a few juveniles (4 mm) were found in July‐August. Mature eggs are extremely large (310 μm), evidently an adaptation to arctic conditions. Throughout the year the interstitial fauna at the type locality was rich, both in species and individuals. Some of the associated fauna included coelenterates, many turbellarians, nemerteans, chaetonotid gastrotrichs, archiannelids and polychaetes and, less abundantly, a few gnathostomulids, macrodasyid gastrotrichs, nematodes, eutardigrades, halacarids, harpacticoid copepods and ostracods.
Untersuchungen zur Taxonomie der Gattung Araniella (Araneae, Araneidae)BLANKE, RAINER
doi: 10.1111/j.1463-6409.1982.tb00540.xpmid: N/A
Morphological and ethological criteria were used in studying the taxonomic relations between different forms within the genus Araniella. Criteria for a diagnosis of all species and subspecies of the genus are given. A. opisthographa (Kulczyǹski, 1905), A. cucurbitina (Clerck, 1757), A. proxima (Kulczyǹski, 1885) and A. maderiana (Kulczyǹski, 1905) form one group of sibling species in the narrowest sense, A. alpica (L. Koch, 1869) and A. inconspicua (Simon, 1874) a second distinct one. A. displicata (Hentz, 1847) seems to occupy a relatively isolated position. A. cossoni (Simon, 1885) is regarded as a synonym for A. cucurbitina. It is impossible to make a statement about the status of A. silesiaca (Fickert, 1876) and A. croatica (Kulczyǹski, 1905) because of the lack of sufficient material. A. silesiaca is not a synonym for Araneus crispulus Tullgren, 1952, a species which does not belong to the genus Araniella.
Cichlid Fishes from the La Plata Basin. Part IV. Review of the Apistogramma Species, with Description of a New Species (Teleostei, Cichlidae)KULLANDER, SVEN O.
doi: 10.1111/j.1463-6409.1982.tb00541.xpmid: N/A
Apistogramma inconspicua sp.n. is described from the Rio Candclaria in the Rio Guaporé drainage in Bolivia, and recorded also from Cáceres on the Rio Paraguay in Brazil. The new species is closely related to the Paraguayan species A. commbrae (Regan) and an undescribed species in the Guaporé drainage system. These species share a specialized feature in the colour pattern, viz. an expanded vertical bar on the caudal peduncle which it confluent with the caudal spot. The now presumably complete record of Paraguayan Apistogramma species allows an analytical key to be given. Of the additional species, A. borellii (Regan) and A. trifasciata (Eigenmann & Kennedy) represent two distinct lineages. Apistogramma pleurotaenia (Regan) is probably a La Plata basin species, although no localities are known, and its relationship remain obscure. The assemblage of Paraguayan Apistogramma species reflects the heterogeneity of the Paraguayan cichlid fauna as a whole.