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 90-(155-272)-275 μm long, (4-7)-8 μm wide, L/W = 25-40; slightly curved but straight at the center, tapered at both ends; cell wall smooth without bands (Illustrations of the Japanese Fresh-Water Algae, 1977).

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

Images of collecting locality: Ko-numa (pond/marsh), Minakami town (formerly Tsukiyono town), Gunma Pref., Japan, April 15, 2007 by Y. Tsukii