Ergasilid copepods (Poecilostomatoida) in plankton samples from Hokkaido, Japan, with reconsideration of the taxonomic status of Limnonvaea Kokubo, 1914.

Three species of ergasilid copepods are described from plankton samples collected in Hokkaido of northern Japan: Ergasilus bani n. sp., E. hypomesi Yamaguti,1936 and E. genuinus (Kokubo, 1914) n. comb. The last was originally assigned to an enigmatic genus Limnoncaea Kokubo, 1914. In this paper Limnoncaea is relegated to a junior synonym of Ergasilus Nordmann, 1832, while the type species, L. genuina Kokubo, 1914 is transferred accordingly to Ergasilus. Transformation in adult female of ergasilids from the planktonic to the infesting stages is also discussed. Comparison of ovigerous females from host fish and plankton samples suggests that ergasilids may lead dual life cycles in freshwater. [ABSTRACT FROM AUTHOR]