Petalomonas micra Norris, 1964. Cells spherical, slightly flattened, usually with a very short neck from which a single flagellum emerges. Flagellum two to three times longer than the diameter of the cell. Periplast firm, with no ridges or markings. Cell clear, containing numerous small spherical granules. Nucleus usually located in the posterior end of the call. Some cell contain irregular-shaped bodies, probably food vacuoles. Cells from 3.5 to 6 microns in diameter.
