Genus Vannella Bovee, 1965
Diagnosis: Locomotive form commonly flabellate or fan-shaped, often semi-circular with broad hyaline margin around sides, or in some spatulate with long tail; flattened anterior hyaloplasm occupying up to half the length of the cell; breadth usually greater than length making the cell commonly fan-shaped; no longitudinal wrinkles; floating form of all freshwater species and most marine species with pseudopodia tapering markedly, sometimes pointed, sometimes tightly helical; nucleus with central nucleolus; cysts have not been found in any species classified with certainty in this genus.
Ultrastructure: cell coat of examined species has pentagonal glycostyles slightly more than 100 nm tall.
Remarks: Common in both fresh water and marine habitats. The species problem seems difficult in Vannella. Given its commonness, it may not be possible to assign all isolates to named species. Vannella is hard to distinguish with certainty from Platyamoeba (Page, 1988). and the recently described Ripella.