Genus: Colonies spherical, with inner empty space; cells attached to each other by a protrusion of cell wall, arranged in a single layer; cell body mostly spherical with some conical or grobular bulges; chloroplasts cup-shaped with a pyrenoid; reproduction by asexual coenobium (Illustrations of The Japanese Fresh-water Algae, 1977).
Species: Colonies of 8, 16, 32 or 64 cells, spherical in shape; cells spherical, covered by a delicate gelatinous sheath; sheaths with 5 or 6 short, stout, truncate processes radially projected and a single process toward the outer face of the cell; cells connected to adjacent ones by marginal processes of the sheath; intercellular spaces circular or triangular; cells 6-21 μm diam. (Photomicrographs of the Freshwater Algae, 1996).