Genus: Test variable, chitinoid; binucleate (Illustrated Guide, 1985).
Species:
Arcella sp.,
test 90-95 μm in diam., 68 μm high, pseudostome 28 μm in diam.,
x 640, near Okubo ike (pond as water reservoir), Shinano town, Nagano Pref., Japan, November 7, 2004 by Y. Tsukii
50 μm
100 μm
150 μm; x 400 :
31 μm
63 μm
94 μm; x 640