Genus: Test variable, chitinoid; binucleate (Illustrated Guide, 1985).
Species:
Arcella sp.,
test 103 μm in diam., pseudostome 26 μm in diam.,
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