Phyllomitus vesiculosus Larsen and Patterson, 1990. Sac-shaped body, 11-15 microns long, slightly dorso-ventrally flattened. Two flagella arising from large anterior depression, anterior flagellum extending in front of the cell with a long sweeping curve, the posterior flagellum trailing behind. The nucleus lies near the cell center, adjacent to the base of the flagella, a rod or bar lies against one anterior side of the nucleus. The outer region of the cytoplasm is highly vesiculate, vesicles with granules. Moves by swimming, frequently in the immediate vicinity of the substratum, with the posterior flagellum dragging against the substratum.