Présence d’Asellides stygobies (Crustacea, Isopoda, Aselloidea) dans la région du Primorye, Sibérie sud-orientale

Two species of anophthalmous, unpigmented asellids have been found in springs and groundwaters of S.E. Siberia (Primorye region). Asellus (Asellus) primoryensis n. sp. is closely related to the epigean species A. (A.) hilgendorfii Bovallius, 1886, as is the case for all stygobiont Asellus (Asellus) species previously known from the Japanese archipelago. Sibirasellus parpurae n. g., n. sp. is closely related to the microphthalmous species Asellus dentifer Birstein & Levanidov, 1952 from the Ussuri Basin (Khor region), now type-species of the new genus Sibirasellus. These two species show several original characters: body covered by numerous cuticular squamulae, mandibular palp reduced (glabrous and 2-segmented), and coxopodites of pereopods reduced and coalescent with their sternites, pointing to certain affinities with the stygobiont Japanese genus Nipponasellus Matsumoto, 1962 and probably to the epigean species of the “latifrons” group of the genus Asellus, presently restricted to arctic Siberia and western Alaska. The different asellid lines living in the Far East and Pacific North America are much more related with each other than with all other lines of the family. All these forms possess a copulatory system built on the “Asellus pattern”: Endopodite of 2nd male pleopod with a spur-shaped basal apophysis or “processus calcariformis”, an afferent spermatic opening with a labial spur or “processus cylindriformis”, and 2nd exopodite segment with a tergal or “catch lobe”. This phyletic system includes the genus Asellus Geoffroy, 1762 (the present status of which is discussed herein), its subgenera Asellus Dudich, 1925, Mesoasellus Birstein, 1951, and Phreatoasellus Matsumoto, 1962, and its related genera Calasellus Bowman, 1981, Nipponasellus Matsumoto, 1962, Uenasellus Matsumoto, 1962, and Sibirasellus n. g.