Oligochaeta (Annelida) of Lake Kurilskoe, Kamchatka Peninsula

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Lake Kurilskoe (77.05km^2, maximum depth 316m; 104m above sea level) is an oligotrophic caldera lake on the southern Kamchatka Peninsula, Russian Far East. The littoral zone is devoid of macrovegetation. During a hydrobiological study in 1994-1998, 43 taxa of oligochaetes were found, 26 of them identified to the species level. The littoral zone was inhabited mostly by the Enchytraeidae, Lumbricillus pagenstecheri (Ratzel, 1869), L. arenarius (Michaelsen, 1889), Mesenchytraeus kuril Healy and Timm, 2000, Marionina charlottensis Coates, 1980, and M. klaskisharum Coates, 1983. Propappus arhynchotus Sokolskaya, 1972 and Haplotaxis gordioides (Hartmann, 1821) were also sometimes abundant. Naidinae included a large form of Nais communis Piguet, 1906, together with N. variabilis Piguet, 1906, N. pardalis Piguet, 1906, and Pristina aequiseta Bourne, 1891. Tubificidae s.s. and Lumbriculidae preferred the deeper littoral and sublittoral areas of the lake. The profundal zone was inhabited by Embolocephalus kurenkovi (Sokolskaya, 1961), Limnodrilus profundicola (Verrill, 1871), Tasserkidrilus americanus (Brinkhurst and Cook, 1966), and Styloscolex opisthothecus Sokolskaya, 1969, all in great abundance. Many oligochaete species widely distributed in nearby regions were not found in this lake.