Genus: Clear pseudopods, formed from clear anterior, more or less broad margin (Illustrated Guide, 1985). Group II: Subpseudopodia, broadly based mammilliform or nearly hemisperical pyramids. (b2: Pseudopods triangular; locomotive less than 100 μm) Species: 50-125 (usually < 100) μm; L/B to 4.5; with shallow anterior hyaline edge which bears several mamilliform pseudopodia; may divide into Y shape in changing direction; floating form usually irregularly rounded, very rarely radiate; nucleus 6.5-10 μm (Page, 1976).

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

Mayorella penardi, stock Tok-1, cysts, x 400, x 640, Kagami-ike (pond), Otawara city, Tochigi Pref., August 2000, by Y. Tsukii