Genus: Planktonic; colony of 16, 32 or 64 cells, irregular in shape, without gelatinous sheath; colony consists of subsets of 4 cells connected by gelatinous filaments extending from the center; each subset consists of cells of two types, 2 cells located outward, kidney- or heart-shaped, other 2 cells located inward, cylidrical, both ends rounded; a single chloroplast plate-like in shape, slightly curved, with a pyrenoid (Guide book to the "Photomicrographs of the Freshwater Algae", 1998).
Species: