Genus Belonocystis Rainer, 1968 emend. Klimov et Zlatogursky, 2016

Diagnosis: Spherical cells, moving by fine pseudopodia. Cells are covered with tightly packed organic scales, which together give an impression of a single polygonal capsule. Scales have a widened base and narrow spike, which originates from the distal part of the base. Cytoplasm is not divided into ecto and endoplasm, and contains light-refractive granules. Nucleus eccentric, with a compact spherical nucleolus. Contractile vacuoles, if present, around the cell periphery. Up to four contractile vacuoles may be present. Tubular mitochondrial cristae. Some species can form abnormally large cells.

Dimensions: Cell body diameter 8-16 µm.

Ecology: Bacterivorous. Freshwater and marine; North America, Europe.