Genus: Pseudostome lacks lobed collar; test round or oval in cross-section;
with or lacking a collar (Illustrated Guide, 1985).
Species: Test pyriform, flask-shaped, or ovoid; neck variable in length;
aperture terminal, typically circular; test composed of angular sand-grains, diatoms;
60-580 μm by 40-240 μm (Kudo, 1966).
Difflugia oblonga Ehrenberg (or D. pyriformis ?),
test 185 μm long, 115 μm wide, L/W=1.6,
pseudostome 50 μm wide,
x 400, x 640, a pond near the entrance of climbing route to Omine mountain, Minakami town (formerly Tsukiyono town), Gunma Pref., Japan, May 25, 2006 by Y. Tsukii
31 μm
63 μm
94 μm; x 640
Images of collecting locality:
a pond near the entrance of climbing route to Omine mountain, Minakami town (formerly Tsukiyono town), Gunma Pref., Japan, May 25, 2006 by Y. Tsukii