Genus: Filament without branching; cell body cylindrical; each cell wall consists of two parts with "H" structure overlapping at the midregion; chloroplasts many, disc-shaped, without pyrenoids (Guide book to the "Photomicrographs of the Freshwater Algae", 1998). Species: Filament 3-4 μm wide; cell body up to 3 times longer than its width; usually with 2 parietal disc or band-shaped chloroplasts (Süßwasserflora von Mitteleuropa 3, Xanthophyceae 1, 1978).

31 μm 63 μm 94 μm; x 640

Images of collecting locality: A small dam at Ichinokawa (river) near Suwa-numa, Minami-yoshimi, Yoshimi town, Saitama Pref., Japan, March 25, 2006 by Y. Tsukii