Family: Test rigid, chitinoid, often areolar, smooth; pseudostome ventral, round
(Illustrated Guide, 1985).
Genus: Test variable, chitinoid; binucleate (Illustrated Guide, 1985).
Species: 30-70 μm diam.,
25-40 μm high;
pseudostome round, 10-20 μm,
invaginated 8-10 μm, short inverted rim;
test finely areolar, yellow to brown (Illustrated Guide, 1985).
Arcella sp.,
x 400, Higashi-hiroshima, Hiroshima Pref., Japan, September 1998 by Y. Tsukii
