Species: Cell body flat, anterior narrowed, posterior broadly rounded, with short blunt cauda, 30-40 μm long, 20-30 μm wide, cauda usually straight, but rarely slightly curved, dorsal furrow short and shallow, lateral margins broadly rounded or nearly straight, periplasts longitudinally striated, usually a single large paramylon body but sometimes accompanied with a second smaller one (Photomicrograph of the freshwater algae, 3: 71, 1985). Cell body 23-40 μm long, 20-30 μm wide, dorsal view nearly spherical; cauda short V-shaped and slightly curved or straight, striae also straight; a locomotive flagellum nearly the same as the cell body in length; paramylon bodies disc-shaped with a hole at the center, 1-2 in number; (An Illustrated Guide to Freshwater Zooplankton in Japan, 2000).

31 μm 63 μm 94 μm; x 640

Phacus acuminatus, cell body μm long, μm wide, x 640, near Yanase river, Mizuko, Fujimi city, Saitama Pref., Japan, December 2003 by Y. Tsukii
31 μm 63 μm 94 μm; x 640

Phacus acuminatus Stokes var. acuminatus: Cell body flat, anterior narrowed, posterior broadly rounded, with short blunt cauda, 30-40 μm long, 20-30 μm wide, cauda usually straight, but rarely slightly curved, dorsal furrow short and shallow, lateral margins broadly rounded or nearly straight, periplasts longitudinally striated, usually a single large paramylon body but sometimes accompanied with a second smaller one (Photomicrograph of the freshwater algae, 3: 71, 1985).