Genus: Cell body crescent in shape (long, curved, tapered at both ends); cross section rounded;
cell wall smooth or with longitudinal lines, bands on the cell wall in some species;
chloroplast laminae ridged and radially arranged, which makes cross section star-shaped;
pyrenoids aligned or scattered (Illustrations of The Japanese Fresh-water Algae, 1977).
Species: Cell body 130-(154-280) μm long, 15-25 μm wide, L/W=10-12; slightly swelled at the center, innter side nearly straight, both ends rounded; cell wall smooth, transparent; 5-7 pyrenoids in each semicell (Illustrations of The Japanese Fresh-water Algae, 1977).