Genus: Planktonic; unicellular or colony of 4, 8, or 16 cells; both cells and its colony covered with layers of mucous sheath;
cell body spherical; cell wall smooth; a single chloroplast star-shaped, with a pyrenoid located at the center
(Guide book to the "Photomicrographs of the Freshwater Algae", 1998).
Species: Cell body spherical, 15-20 μm in diam.; a single chloroplast star-shaped, with a pyrenoid (Illustrations of The Japanese Fresh-water Algae, 1977).