Genus: Pseudostome lacks lobed collar; test round or oval in cross-section; pseudostome relatively large, with or lacking a collar (Illustrated Guide, 1985). Species: 100-300 μm long; 120-320 μm wide (diam.); with up to 15 spines at level of broadest diam as a crown; pseudostome round, 4-20 dentate lobes, 50-150 μm diam. (Illustrated Guide, 1985). Test ovoid to spheroid, circular in cross-section; crown broadly rounded, with a variable number of spines; aperture (pseudostome) more or less convex in profile, central and its border multidentate or multlobate; test with fine sand-grains, opaque; 180-230 μm long, about 150 μm wide (diam.) (Kudo, 1966). QuickTime Movies http://protist.i.hosei.ac.jp/

100 μm 200 μm 300 μm; x 200 : 50 μm 100 μm 150 μm; x 400