Genus: Colony spherical; 8-16 cells of similar size, close together, mutually compressed; 2-layered gelatinous envelope; cells with 2 equal-length flagella; 2 contractile vacuoles anterior; nucleus central (Illustrated Guide, 1985). Species: Colonies spherical in shape, consisting of 16 or 8 cells; cells pear-shaped, up to 26 μm in surface diam., contiguous at the center of the colony; a single chloroplast, cup-shaped, with 4-8 pyrenoids (Photomicrographs of the freshwater algae, vol. 11, 1993).

50 μm 100 μm 150 μm; x 400 : 31 μm 63 μm 94 μm; x 640