The crustacean fauna of Bayan Onjuul area (Tôv Province, Mongolia) (Crustacea: Branchiopoda, Copepoda, Ostracoda)

Due to the wide extension of the country and to the shortness of the ice-free season, the inlandwater crustacean fauna of Mongolia is, to date, incompletely known. However, based on the available literature, Mongolian inland waters appear to be characterised by a high biodiversity, including some taxa still waiting to be described. Novel data on the branchiopod, copepod, and ostracod crustaceans from central Mongolian steppe, from the “Tuul” and “Umard goviin guveet-Khalhiin” hydrographical basins, are presented herein. While large branchiopods, some anomopod families, and copepods are well-represented in the collected samples, ostracods are rare, and the anomopod family Chydoridae is apparently absent in the sampled water bodies. The anomopod Macrothrix dadayi and the cyclopoid Microcyclops afghanicus are here reported for the first time for the Mongolian fauna. Furthermore, two branchiopods (i.e. Moina sp. and Artemia sp.), three copepods (i.e. Diacyclops sp., Arctodiaptomus cf. alpinus, and Arctodiaptomus cf. wierzejskii), and one ostracod taxon (i.e. Heterocypris sp.), were not identified to species level and therefore deserve further study. The main ecological determinants of species distribution in the study area were examined using canonical multivariate analysis, which explained around 40% of total variation of the species similarity matrix; the main environmental drivers of crustacean assemblages in the study area were elevation, water turbidity, water temperature and electrical conductivity. The ecological preferences of crustacean species in the area are briefly discussed.