Genus: Two flagella of equal length inserted close together into an anterior papilla of variable shape
usually directed anteriorly; chloroplast form variable; usually 2 contractile vacuoles;
cell division producing 2-8 zoospores; sexual reproduction usually isogamous,
anisogamy and oogamy known but rare; > 500 species, mostly fresh water (Illustrated Guide, 1985).
A large chloroplast; stigma; a single nucleus; two contractile vacuoles anterior (Kudo, 1966).
Species: Cell body spherical in shape, 10-20 μm in diam., papilla absent, cell wall thickened, flagella 1.5 times longer than the cell body, chloroplast filled cell body,