Genus: Pseudostome lacks lobed collar; test round or oval in cross-section; pseudostome at end of bent neck; test more or less coiled or folded (Illustrated Guide, 1985). Species: 120-150 μm long, 100-140 μm wide; test with constriction at base of neck; pseudostome round, 28-35 μm long (Illustrated Guide, 1985).

50 μm 100 μm 150 μm; x 400 : 31 μm 63 μm 94 μm; x 640

Images of collecting locality: Yukawa-numa (pond), Nishiwaga-machi (town), Iwate Pref., Japan, July 28, 2007 by Y. Tsukii

* Lesquereusia gibbosa Thomas & Gauthier-LiŽvre, 1959: 120-150 μm long, 100-140 μm wide; test with constriction at base of neck; pseudostome round, 28-35 μm long (Illustrated Guide, 1985).

Lesquereusia spiralis (Ehrenberg, 1840): 95-190 μm long, 75-150 μm wide, 50-100 μm deep; test like flask, neck against body; with secreted imbedded siliceous particles; pseudostome circular 30-50 μm diam. (Illustrated Guide, 1985).