Genus: Two chloroplasts with axis and laminae structure; axis short, laminae also short making the chloroplasts star-shaped Species: Cell body cylindrical, large, 20-87 μm long, 11-35 μm wide (Photomicrographs of the Fresh-water Algae, 1984). [var. brebissonii]: Cell body cylindridal with both round ends, 30-87 μm long, 14-35 μm wide, L/W=2-4; chloroplasts star-shaped, with a single pyrenoid. [var. minor]: Cell body 20-30 μm long, 8-13 μm wide (Illustrations of The Japanese Fresh-water Algae, 1977).

Similar genus -->> Zygnema; Penium; Mesotaenium;

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

Cylindrocystis brebissonii , x 400, x 640, Watarase-Yusuichi, Fujioka town, Tochigi Pref., May 2001 by Y. Tsukii

Cylindrocystis brebissonii, cell body μm long, 55 μm wide, x 400, x 640, Watarase-Yusuichi, Fujioka town, Tochigi Pref., May 2001 by Y. Tsukii

Cylindrocystis brebissonii Meneghini var. brebisonii: Cell body cylindrical, large, 30-87 μm long, 14-35 μm wide, L/W= 2-4; zygospores rectangular (Illustrations of The Japanese Fresh-water Algae, 1977).

Cylindrocystis brebissonii var. jenneri (Ralfs) Hansgirg: Cell body cylindrical, large, 20-70 μm long, 11-23 μm wide; zygospores spherical (Illustrations of The Japanese Fresh-water Algae, 1977).

Cylindrocystis brebissonii var. minor W. et G.S. West: Cell body cylindrical, small, 20-30 μm long, 8-13 μm wide (Illustrations of The Japanese Fresh-water Algae, 1977).

Cylindrocystis crassa Debary: Cell body ellipsoidal, 20-60 μm long, 17-31 μm wide (Illustrations of The Japanese Fresh-water Algae, 1977).