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: Cell body constricted in the middle, sinus narrow-linear part but acutely open outward, 11-22 μm long, 24-39 μm wide, L/W=2, constriction 21-28 μm wide; vertical view of cells triangular, sides straight, angles rounded; apex broad, with a short connecting process at each apical angle, excavated in the middle and forming a oblong hollow cavity between the adjacent cells; semicells transversely subrectangular, lateral margins obliquely truncate; filaments twisted (Photomicrographs of the Freshwater Algae, vol. 1, 1984).
Images of collecting locality:
Drainage ditch near Odate railway station, Odate city, Akita Pref., Japan, September 22, 2007 by Y. Tsukii