Genus: Test variable, chitinoid; binucleate (Illustrated Guide, 1985).
Species:
Arcella sp.,
test μm high, 130 μm wide, H/W=, pseudostome 55 μm wide,
x 640, Kurome river, Asaka city, Saitama Pref., Japan, January 8, 2006 by Y. Tsukii
31 μm
63 μm
94 μm; x 640