Genus: Cell body short, with a deep constriction at the center, apical view fusiform or radially symmetrical; cell apexes without spiny projections; intermediate zone or folded structure appeared during cell division; zygospores remain within their mother cells (Illustrations of The Japanese Fresh-water Algae, 1977). Species: (Photomicrographs of the Freshwater Algae, vol. 1, 1984).