Spiders (Aranei) of the Belyaka Spit, Chukotka: peculiarities of thefauna and biotopic distribution

摘要

Eighteen spider species of four families have been collected by pitfall trapping from the Belyaka Spit in Kolyuchin Bay; northern coast of the Chukchi (= Chukotka) Peninsula: Linyphiidae (15 species), Lycosidae (1), Thomisidae (1) and Tetragnathidae (1). Twelve species are newly recorded from the spit. The composition of the spider fauna is typical for the northern part of the tundra zone and is characterized by predominance of purely Arctic spiders. Based on the composition of dominant species, twotypes of spider assemblages were revealed: 1) seaside-zone spider community in sandy-pebble habitats with halophytic vegetation, with Erigone arctica sibirica Kulczynski, 1908, Halorates holmgreni (Thorell, 1871) and H. spetsber-gensis (Thorell, 1872) aspredominants; 2) tundra and swamp vegetation spider community with Pardosa al-gens (Kulczynski, 1908) as a superdominant. The spider assemblages of wetlands are rich in species (15 species, 83% of the local araneofauna). The most typical for northern Asia hygrophilous Arctic species are presented here rather completely, including Erigone psychrophila Thorell, 1872, Hilaira vexatrix (O. Pick-ard-Cambridge, 1877), Hybauchenidium aquilonare (L. Koch, 1879), Masikia indistincta (Kulczynski, 1908), and Silometopoides pampia (Chamberlin, 1948), being the most abundant. The Belyaka Spit is the easternmost locality of the known distribution of Semljicola bar-biger(L. Koch, 1879).