Species: Cell body cylindrical or ellipsoidal, tapered to both ends, 35-79 μm long,
(16-21)-36 μm wide; both ends broadly rounded; cell wall thin, brownish in color,
finely lined (15-18/10 μ)
(Illustrations of The Japanese Fresh-water Algae, 1977).
Penium polymorphum Perty or Netrium ?,
cell body 55 μm long, 18 μm wide, L/W=3.1,
x 640, a small wetland near Numa-no-hara marsh (Genseikaen), Madarao highland (Niigata & Nagano Pref.), Myoko village, Niigata Pref., Japan, May 15, 2005 by Y. Tsukii
31 μm
63 μm
94 μm; x 640
Cell body 54 μm long, 18 μm wide, L/W=, x 640
Cell body 70 μm long, 20 μm wide, L/W=, x 640