Water mites (Acariformes, Hydrachnidia) of the Sob River basin (Polar Urals)

Water mites were investigated in water bodies of the Sob River basin, which flows in the central part of the Polar Urals, in the region of the Arctic Circle. The upper and middle courses of the River Sob, its tributaries in the mountainous and plain regions, as well as lakes and floodplain ponds were studied. In total, 35 species from 8 families were identified from 12 waterbodies, 24 species were found in rivers and 12 species in lakes. It was found that the fauna of water mites in the rivers was very rich and diverse. Lebertiidae, Sperchontidae and Hygrobatidae dominated in terms of species number and abundance. The fauna of the mountain rivers was poorer than that of the plain rivers. Feltria minuta and Sperchon glandulosus dominated in different sites of the upper course of the Sob River and its mountain tributaries. The highest number of mites and the greatest diversity of species were found in the middle reaches of the Sob River and its tributaries in the plain area. Species of the genera Atractides and Lebertia dominated in these rivers. The number of mites was low in lakes and they were represented by a small number of species. In stagnant waters, Lebertia litoralis and species of the genus Piona predominated in abundance and occurrence. The fauna of water mites in the River Sob basin is similar to other parts of the Urals, especially in the Nether-Polar Ural water bodies. In comparison with the southern regions of the Urals, the species composition of water mites in the Polar Urals is poorer. Some genera and families that are numerous in the Central and Northern Urals are absent. In the same time species of northern and eastern origin such as Sperchonopsis minutiporus and Sperchon laurenticus are present.