Vampyrellida West 1901, emend. Hess et al. 2012

Diagnosis: Exclusively heterotrophic, naked, phagotrophic amoeboid organisms; life cycle includes amoeboid, freemoving trophozoites alternating with an obligatory digestive cyst, in which cell division usually take place; several taxa can fuse to form plasmodia and reach considerable sizes; sexual processes unknown; cytoplasm often differentiated into a finely granular, sometimes highly vacuolated part and structureless hyaloplasm, the latter often surrounding the main cell body, but at least constituting the pseudopodia; free-living in freshwater, soil, or marine environments.

Members of this genus feed on algae.