O Kelly and Nerad, 1999. Cells are 4 - 5 microns long, flattened laterally and with a ventral groove. An anterior flagellum inserts into the anterior end of the cell and is about 1.5 times the cell length. The anterior flagellum is directed to the front and beats actively, and its tip is thin. A posterior flagellum emerges near the anterior end of the ventral groove, and is about 2 times the length of the cell and not acronematic. The flagellum is usually held in a curve. Both flagella are in the same strength. The cells move slowly by skidding. Food vacuoles containing bacteria are seen in the back and posterior part of the cell. Frequently observed in late culture.