Rhabdomonadine euglenid, colourless, omotrophic, never phagotrophic, rigid, elongated, curved, flattened cells, narrowly triangular or elliptical in cross-section; pellicle with delicate striations; canal opening apical, anterior end of cell protruded into a narrow neck; cell contents include large paramylon links and typically show cytoplasmic streaming; cysts and palmellae unknown; freshwater, worldwide; type species: M. pellucidum, Perty, 1852.