Genus: Unicells or a colony of spherical cells covered with a distinct sheath. Species: Colonies consisting of many cells lacking definite layers; colonies formed by small subsets of 2, 4 or 8 cells; cell body (excluding sheath) larger than 5 μm in diameter (6 - 11 μm) (Illustrations of The Japanese Fresh-water Algae, 1977).

Images of collecting locality: Fujimi-hotaru-shinsui Park, Okegawa city, Saitama Pref., Japan, January 29, 2006 by Y. Tsukii