Genus: Cell body ellipsoidal-ovoidal with cell wall;
Four euqal-length flagella arising from an anterior depression of the cell body;
chloroplast cup-shaped with a pyrenoid at the bottom; a single stigma large;
two contractile vacuoles at the base of flagella
(An Illustrated Guide to Freshwater Zooplankton in Japan, 2000).
Species: Cell body ovoidal, 16-23 μm in diam.; anterior depression 1/5-1/6 of the body length; a single circular stigma located at the equatorial line (An Illustrated Guide to Freshwater Zooplankton in Japan, 2000).