Family: With two flagella; one directed anteriorly and the other posteriorly and trailing
(recurrent flagellum); flagella orininate in anterior end; one to several contractile vacuoles (Kudo, 1966).
Genus by Ehrenberg (Illustrated Guide, 1985) or Klebs (Kudo, 1966): With 1 kinetoplast; cytostome near the tip of a prominent proboscis that moves with the short anterior flagellum (Illustrated Guide, 1985). Similar to Bodo, but there is an anterior extension of body, where an anterior flagellum is embedded, the other trails; a single nucleus; fresh and salt water (Kudo, 1966).
* Rhynchomomas nasuta (Stokes): Oval, flattened; 5-6 μm long, 2-3 μm wide; fresh water and coprozoic (Kudo, 1966).
Rhynchomomas marina (Faria, da Cunha and Pinto): salt water (Kudo, 1966).