Genus: Spherical or ellipsoidal colony composed of 2-50 ovoid cells arranged radially; cell body usually covered by short bristles; two chloroplasts lateral; no stigma; longitudinal cell division; fresh water (Kudo, 1966).
Species: Cells oval; bristles conspicuous; 20-40 μm long, 8-17 μm wide (Kudo, 1966).