Vannella simplex (Wohlfarth-Bottermann, 1960) Bovee, 1965

Diagnosis: Locomotive form semicircular or fan-shaped, often with long ‘tail’. Frontal hyaloplasm occupies about half of the cell; the front edge may be smooth or slightly wavy. Rapidly moving cells often have a long ‘tail’; in cultures and moist-chamber-preparations amoebae are commonly covered with patches of fecal pellets. Locomotive forms vary in size. Rounded vesicular nucleus with single spherical central nucleolus. Floating form of radial type, with a number of fine, tapering hyaline pseudopodia.
Ultrastructure: Cell surface is covered with glycostyles about 100 nm in length; simple, filaments present among them.

Dimensions: Locomotive forms 25—80 µm in greatest dimension (average 42—52 µm). Nucleus 6—11 µm in diameter.

Ecology: Freshwater, in different water types. Common in moist-chamber-slides where it multiplies easily.