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 inlandwatercrustacean fauna of Mongolia is, to date, incompletely known. However, based on the availableliterature, Mongolian inland waters appear to be characterised by a high biodiversity, including some taxastill waiting to be described. Novel data on the branchiopod, copepod, and ostracod crustaceans from centralMongolian steppe, from the “Tuul” and “Umard goviin guveet-Khalhiin” hydrographical basins, arepresented herein. While large branchiopods, some anomopod families, and copepods are well-represented inthe collected samples, ostracods are rare, and the anomopod family Chydoridae is apparently absent in thesampled water bodies. The anomopod Macrothrix dadayi and the cyclopoid Microcyclops afghanicus are herereported for the first time for the Mongolian fauna. Furthermore, two branchiopods (i.e. Moina sp. andArtemia 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 furtherstudy. The main ecological determinants of species distribution in the study area were examined usingcanonical multivariate analysis, which explained around 40% of total variation of the species similaritymatrix; the main environmental drivers of crustacean assemblages in the study area were elevation, waterturbidity, water temperature and electrical conductivity. The ecological preferences of crustacean species inthe area are briefly discussed.