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).

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

Closterium ehrenbergii Meneghini var. ehrenbergii: Cell body large, swelled at center, tapered at both termini, 150-(176-323)-380 μm long, 15-(20-28)-40 μm wide, L/W= 4-6; cell wall smooth, colorless, with no bands; 5-8 pyrenoids in each chloroplast (Illustrations of The Japanese Fresh-water Algae, 1977).