Genus: Emergent flagellum mobile throughout its length during swimming; colourless; no eyespot;
cell body rigid; cylindrical, not flattened; canal opening subapical; paramylon and lipid abundant;
fresh water (Illustrated Guide, 1985).
Body rigid, cylindrical, more or less arched; pellicle longitudinally ridged;
a flagellum at apex (Kudo, 1966).
Rhabdomonas incurva: Banana-shaped; longitudinal ridges; flagellum as long as cell body; 15-25 μm long, 7-8 μm wide (Hall, 1923), 13-15 μm long, 5-7 μm wide (Hollande, 1952); standing water (Kudo, 1966).
Rhabdomonas costata (Korschikoff) Pringsheim: Body curved, cylindrical, 25-30 μm long, 7-10 μm wide, emergent flagellum 10-20 μm long; large Golgi bodies just posterior to reservoir; lipid droplets in tail region (Illstrated Guide, 1985).