Genus (Ehrenberg, 1830): Spheroidal; cytoplasm vacuolated, especially ectoplasm; nucleus central;
one to many contractile vacuoles; axopodia straight, axial filaments terminate at surface of the
nucleus (Kudo, 1966).
Species: Ectoplasm vacuolated; a large central nucleus; diameter average 40-50 μm (Kudo, 1966).
Images of collecting locality:
a wetland at Igashira park, Mooka city, Tochigi Pref., Japan, April 1, 2006 by Y. Tsukii