Ciliophrys infusionum Cienkowski, 1876
Diagnosis: Cell spherical, with numerous axopodia which are connected to the surface of the central nucleus; cell in heliozoan stage closely attached to the substrate by a short stalk from its posterior end; one single apical cilium usually immotile or moving slowly in a figure 8 or S configuration; swimming stage with resorbed axopodia and the cilium pointing forward; swimming cells often ovate to spindle shaped.
The short stalk attaching the cell to the substrate is not easily seen with the light microscope. Cell division occurs in the heliozoan stage, often with a contraction of the axopods.
Dimensions: cells about 7-19 µm.
Ecology: Fresh water, but also reported from marine habitats. Sometimes very common in more eutrophic environment.