Hypogastrura janetscheki STEINER, 1959, bona species Hypogastrura janetscheki STEINER, 1959: 455 Hypogastrura socialis (UZEL, 1891) summer form: JORDANA et al. (1997: 91) Hypogastrura janetscheki STEINER, 1959 (as syn. n. of Hypogastrura socialis (UZEL, 1891): JORDANA et al. (1997: 759) Hypogastrura janetscheki STEINER, 1959 (as cyclomorphic form of Hypogastrura socialis (UZEL, 1891): ARBEA (2007: 120) Material examined. 21 specimens on slides, soil and litter in birch forest, Solenozerna locality, Chornomors’ky Biosphere Reserve, Kherson district, Ukraine, 30. IV. 2006, leg. I. KAPRUS’; 1 specimen, soil and turf, steppe, Jagorlyts’ky Kut locality, Chornomors’ky Biosphere Reserve, Kherson district, Ukraine, 2. V. 2006, leg. I. KAPRUS’; 1 specimen, soil and turf, steppe, Kamiani Mohyly Reserve, Donets’k district, Ukraine, 23. X. 1996, leg. O. STAROSTENKO (18 specimens SMNHL, 5 specimens DBET). Note. H. janetscheki has been recorded from Ukraine for the first time. This species described from Sierra Nevada (S Spain) (STEINER 1959) was recognized as summer form of H. socialis and synonymized by JORDANA et al. (1997). However, judging from the description and figures, H. socialis sensu JORDANA et al. (1997) in fact represents two distinct species different from H. socialis sensu STACH (1949), BABENKO et al. (1994), and FJELLBERG (1998). The summer form of H. socialis sensu JORDANA et al. (1997), characterized by 8 cylindrical sensilla on antennal segment IV, m 2 setae on thoracic tergum II absent, setae m 1 on abdominal tergum IV present, mucro with subapical tooth, and dens with fine tegumentary granulation (JORDANA et al. 1997: fig. 38), is H. janetscheki, and the winter form from Quinto Real (West Pyrenees), with 8 cylindrical sensilla on antennal segment IV, m 2 setae on thoracic tergum II and setae m 1 on abdominal tergum IV absent, mucro with subapical tooth, and dens with some spine-like granules (JORDANA et al. 1997: fig. 39), is H. kelmendica PEJA, 1985 or a related species (see SKARŻYŃSKI & SMOLIS 2003). True H. socialis can be easily distinguished from them by the larger number (10–12) of sensilla on antennal segment IV and the presence of setae m 2 on thoracic tergum II. In the light of these facts H. janetscheki should be considered a valid species. Unfortunately our knowledge of the morphology of H. janetscheki is incomplete. All specimens mentioned by STEINER (1959) were collected in July; therefore, the morphology of winter (cyclomorphic) specimens remains unknown. The Ukrainian material is also imperfect in this respect, as there is only one specimen collected in the autumn. It has fine granules at the basal part of the dens and some larger (but not spine-like) ones near its distal end. Further studies are needed to establish weather H. janetscheki is a cyclomorphic species. Although the Ukrainian population fits the description of H. janetscheki (STEINER 1959, JORDANA et al. 1997), it can also be related to Hypogastrura spei BABENKO, 1994 from Taymir, the Urals, Chukotka, and Armenia, which is a possible synonym of the former species. They differ in the character of dens granulation only. H. spei is a cyclomorphic species with the summer and the winter forms typical of the H. socialis group (BABENKO et al. 1994). Until the morphology of winter specimens of H. janetscheki becomes known, H. spei should be considered as a valid species.

Published as part of Skarżyński, D., 2009, A New Species And A New Interesting Record Of The Genus Hypogastrura Bourlet, 1839 (Collembola, Hypogastruridae) From Ukraine, pp. 23-30 in Acta Zoologica Academiae Scientiarum Hungaricae 55 (1) on pages 28-29, DOI: 10.5281/zenodo.12584895