Genus: Pseudostome lacks lobed collar; test round or oval in cross-section; pseudostome relatively large,
with or lacking a collar (Illustrated Guide, 1985).
Difflugia penardi Hopkinson ?,
test 76 μm long, 50 μm wide, L/W=1.5,
pseudostome 25 μm wide,
x 640, Southern lakeside of Lake Shirakaba, Tateshina town & Chino city, Nagano Pref., Japan, May 21, 2005 by Y. Tsukii
94 μm; x 640