Contribution to the fauna of mollusk-eating marsh flies (Diptera,Sciomyzidae) of Yakutia

A total of 38 species belonging to 14 genera and 2 tribes of the family Sciomyzidae were recorded from Yakutia. Among these species, 23, 6, and 8 species were recorded from Yakutia, eastern Siberia, and Siberia, respectively, for the first time. The fauna of Central Yakutia, comprising 33 species, is examined best of all. The range diversity of investigated sciomyzids is classified into 13 types. Species with Holarctic and trans-Eurasian ranges constitute the largest groups comprising 12 species each. Colobaea punctata, Ilione albiseta, Pherbellia brunnipes, and Sepedon sphegea are very abundant. The species composition of the Yakut fauna noticeably differs from neighboring faunas of the Russian Far East, Mongolia, and Alaska, but the generic composition of these faunas is more similar. The Yakut fauna of the Sciomyzidae is intermediate between the fauna of Mongolia and the faunas of the Russian Far East and Alaska. The fraction of marsh flies in dipteran assemblages of meadow cenoses is usually small, but their abundance in some years grows significantly. The population density of marsh flies in the valleys of large rivers is higher in comparison with that found in isolated alas hollows in the plakors (= euclimatopes). Analysis of the trophic associations of the larvae of the Yakut sciomyzids has revealed 5 out of the 7 groups known in the family.