Filling the gaps: diversity of the freshwater microcrustaceans of Karaginsky Island (Kamchatka, Northwest Pacific)

Freshwater microcrustaceans in the southern part of the Kamchatka Peninsula are relatively well-known, however, little research has focused on the northern part of the peninsula. Moreover, relatively few data are available on small water bodies, since most of the studies focused on large lakes and estuarine waters. Here, we present the first data on the microcrustaceans of Karaginsky Island (Kamchatka, Russia) and the adjacent mainland. A total of 100 species, including Branchiopoda, Copepoda, Ostracoda and Amphipoda, were observed in the studied area, which significantly expands our knowledge about the local fauna. Thirty-five species were newly recorded for the Kamchatka Peninsula, and three taxa were new for the whole territory of Russia. At least four taxa showed striking deviations from the typical morphology. The general faunistic composition of Karaginsky Island appears to be typical of Northeast Asia, with a prevalence of Palearctic and cosmopolitan taxa and a smaller proportion of East Asian and Beringian endemics. The faunistic diversity of Karaginsky Island is still not completely revealed, and more surveys are needed to have accurate estimations of biodiversity there.