Amoeboid cell body, more or less elliptical, 11-14microns long, with the posterior end of the cell giving rise to irregular thin cytoplasmic protrusions. The flagellum inserts apically, variable in length but up to about 50microns long, beats very stiffly. If gliding, the cells are drawn out and the flagellum beats in a plane perpendicular to the substratum: when swimming the body is more spherical and is wagged from side to side by the action of the flagellum. The cell body is smooth, lacking extensions or adhering material. A cone-shaped nucleus is located at the apex of the cell.