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: Spherical colonies of 8, 16 or more cells within a gelatinous coat; cell body spherical 9-10 (-24) μm in diam., with 4-10 (-14) small truncate, wart-like processes; cells connected to adjacent ones by the basal stout processes (Photomicrographs of the Freshwater Algae, vol. 5, 1986).

31 μm 63 μm 94 μm; x 640

Images of collecting locality: O-ike, Shiroyama Park, Okegawa city, Saitama Pref., Japan, January 29, 2006 by Y. Tsukii

Coelastrum morus W. & G.S. West var. morus: Colonies of 8, 16 or more cells; cells spherical, covered by a delicate gelatinous sheath; sheaths with 4-10 or -14 small truncate, wart-like processes on outer face of the cell; cells connected to another by basal stout processes, 9-10 (-24) μm diam. (Photomicrographs of the Freshwater Algae, 1996).