Biogeographic zonation of the Eurasian fresh waters based on the macrobenthic faunas

: Spatial differentiation of the Eurasian freshwater faunas is analyzed based on the original and published data on the aquatic insects, crustaceans, and mollusks (about 8800 species in total). The Hacker-Dice similarity index is employed as a principal criterion of differentiation. The schemes of biogeographic zonation are constructed for the nine large macrobenthic taxa, namely, Odonata, Ephemeroptera, Plecoptera, Hemiptera, Coleoptera, Trichoptera, Malacostraca, Gastropoda, and Bivalvia. Discussed are principal discordances in distribution of three different ecological-systematic groups of the macrobenthos, namely, limnophylic insects, rheophylic insects, and crustaceans with mollusks. A generalized zonation system of the Eurasian fresh waters is elaborated, which is fundamentally divided into Palaearctic and Oriental Regions. The former is further divided into five subregions: Euro-Ob, Near East, Central Asia, Eastern Siberia, and Japan. The latter is divided into three subregions: Indo-Himalaya, China, and Malay. Preliminary classification of the provinces is also provided. Disagreements between the biogeographic systems of different authors are discussed.