Genus: Two flagella with unequal length emerging from anterior canal, longer one directed anteriorly and held straight during swimming, shorter one curving laterally; cell body colorless, no eyespot, rigid, solitary, cylindrical, usually unflattened, one or more longitudinal lines or grooves present; hyaline inclusion in posterior half of the cell; freshwater and marine (Illustrated guide, 1985). Species:

31 μm 63 μm 94 μm; x 640

Images of collecting locality: a small pond at Kitamoto nature observatory park, Kitamoto city, Saitama Pref., February 15, 2007 by Y. Tsukii