Two new species of the subterranean amphipod genus Stygobromus (Amphipoda: Crangonyctidae) from Siberia, with new data on Stygobromus pusillus (Martynov) and remarks on morphology and biogeographic relationships Author Sidorov, Dmitry A. Author Holsinger, John R. Author Takhteev, Vadim V. text Zootaxa 2010 2478 41 58 journal article 10.5281/zenodo.195357 7e6e70f5-6ff6-4ecc-8809-f221e202792b 1175-5326 195357 Remarks on Stygobromus morphology Morphological investigation of the Siberian Stygobromus with assistance of SEM revealed additional characters that appear to be taxonomically significant. They include: (1) a naked vestigial segment on the tip of antennae 1 and 2 approximately 10 mkm long ( Figs 68, 69 ); and (2) a “squamiferous membrane” located along the inner margin of the propodi of gnathopods 1, 2 ( Figs 71, 73 ) in both new species. In S. anastasiae n. sp. a similar “squamiferous membrane” is located on inner face of both gnathopod propodi at the point of nail origin ( Fig. 72 ). Although this character is found in both sexes, males ( Fig. 74 ) and females ( Fig. 75 ) show some differences in the shape of scales, but which are probably related to age differences of individuals. The term “squamiferous membrane” was used earlier by Henry & Magniez (1995) in a description of the morphology of the asellid isopod male pleopod 2. However, this morphological structure has apparently not been observed in crangonyctid amphipods until now. The “squamiferous membrane” may represent a complicated microtrich characterized by the fusion at the base of bunches of cuticular microtrichs of different lengths ( Mekhanikova & Takhteev 2008 ).