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:

50 μm 100 μm 150 μm; x 400

Images of collecting locality: No.2, Ochiai-numa (pond), Noshiro city, Akita Pref., Japan, September 22, 2007 by Y. Tsukii