Family: Colonies of fixed number of cells (4, 8, 16, 32, or more) arranged 2- or 3-dimensionally;
cells spherical, ellipsoidal, polygonal, etc. in shape; chloroplasts 1 or several, plate-like in shape,
with 1 pyrenoid; reproduction only by asexual autospores.
Genus: Colonies, 3-dimensional; cell body cylindrical or long spindle in shape, radially arranged by attaching at one end to each other (Illustrations of The Japanese Fresh-water Algae, 1977).