Actinophrys sol Ehrenberg, 1830
Diagnosis: Body spherical with protoplasm highly vacuolated. Usually one contractile vacuole which rises and pushes out the surface as a rounded globule before bursting. Pseudopodia extending from all parts of the body, with axial filaments arising from the membrane of the single nucleus. Cyst brown, with several layers, with a mucus layer and a layer of irregular siliceous scales. Sexual reproduction by autogamy after encystment. “”Fressgemeinschaften”” not rare.
Dimensions: Main body 19-90 µm in diameter; nucleus 10-19.2 µm.
Ecology: fresh water, in several water types; common.