ONE NEW SPECIES AND ONE RARE SPECIES OF THE GENUS DIAPHANOSOMA FISCHER 1850 (CRUSTACEA, CLADOCERA, SIDIDAE) FROM THE AMUR RIVER BASIN

The new species, D. amurensis sp. n., and the rare species, D. pseudodubium Korovchinsky 2000, were found in materials collected by the authors in water bodies of the Lower Amur River and Middle and Lower Zeya River basins (southern Khabarovskii and Primorskii regions, Jewish Autonomous Area, and Amurskaya oblast). The former is especially close to D. brachyurum s. str., differing from it, first of all, in the structure of the copulatory appendages in males and in less conspicuous features as the size of the body, head and eye and differences in the armament of the ventro-posterior shell valve margins. The latter features might be revealed only in the Course of detailed comparison of the rather abundant sets of specimens from different populations. The representatives of D. pseudodubium from lakes in the Lower Amur River basin and water bodies of the 7-eya. River basin have rather conspicuous morphological differences but their taxonomic significance may be estimated only after the processing of greater pool of data from various localities.