Encyonopsis montana lacks a stigma. Valves of E. treinishii are larger and have sinuous striae near the central area. Encyonopsis spicula and E. stoermeri, both tropical species, have lower stria densities (13-15 and 10-13 in 10 µm, respectively). Encyonopsis lacusglacialis has wider valves (8.8 - 11.1µm). Encyonopsis neoamphioxys has distinctly dorsiventral valves.