Genus: Biflagellate, both arising from anterior end; one directed anteriorly and the other runs backward over body surface as a trailing (recurrent) flagellum; body plastic (Kudo, 1966). Small (10-15 μm); body is generally pyriform to cylindrical except for an ameboid variable posterior (Illustrated Guide, 1985). Species:

31 μm 63 μm 94 μm; x 640

Images of collecting locality: Drainage ditch near Kondo-numa (Kondo pond) park, Tatebayashi city, Gunma Pref., Japan, February 18, 2006 by Y. Tsukii