Species: Cell body 100-(193-310) μm long, 11-22 μm wide, L/W=9-17; inner side nearly straight, both termini broadly blunted; cell wall smooth, transparent or yellowish in color, bands present; chloroplasts with 4-6 pyrenoids (Illustrations of The Japanese Fresh-water Algae, 1977). 160-280 μm long, 10-20 μm wide, L/W=18-19; slightly curved, gradually attenuated toward both ends with obliquely truncated edges; chloroplasts with 4-9 pyrenoids (Photomicrographs of the Freshwater Algae, vol.1, 1984).

31 μm 63 μm 94 μm; x 640

Closterium abruptum W. West var. abruptum ?, cell body 235 μm long, 11.5 μm wide, L/W=20.4, x 400, x 640, No.1, Shimo-Kenashitai (marsh), Hakkoda mountain, Aomori city, Aomori Pref., Japan, September 13, 2006 by Y. Tsukii
31 μm 63 μm 94 μm; x 640

Images of collecting locality: No.1, Shimo-Kenashitai (marsh), Hakkoda mountain, Aomori city, Aomori Pref., Japan, September 13, 2006 by Y. Tsukii