Genus Protacanthamoeba Page, 1981
Diagnosis: Trophic amoebae indistinguishable from Acanthamoeba. Locomotive form usually between 20 and 40 urn. Nucleus with central nucleolus. Cysts smooth, circular to oval, about 16.5 urn across. Can be distinguished from Acanthamoeba on basis of cyst wall which is without pores and opercula. Freshwater and soil.