Summary. The Hyperamoeba-like amoeboflagellate (Wi7/2-PE) has been isolated from a hydrotherapy pool inside a hospital at Wildbach/ Germany. Based on combined morphological and molecularbiological data we conclude that this isolate can neither be assigned to the genus Hyperamoeba nor to any of the myxogastrean slime moulds, which are the closest relatives of Hyperamoeba. We thus considered describing this isolate within a new genus, Pseudodidymium, as a new species, Pseudodidymium cryptomastigophorum. As observed by phase contrast microscopy the gross morphology and size of the three stages -trophozoite, cyst, and flagellate stage -is comparable to respective characters of Hyperamoeba as described b