[ref. ID; 2014]
Flexible, ellipsoidal, dorso-ventrally flattened body with large AZM a third to half body length. 2 rows of marginal cirri, joining posteriorly; caudal cirri absent. However, sometimes 3 of the posterior left marginal cirri are well developed and may be mistaken at first glance for caudal cirri. Typical fronto-ventral and transverse systems of cirri, often with 3 strongly developed anterior frontal cirri. All cirri generally long. The genus distinguished by the strong development of the right peristomial lip bending anteriorly and to the left towards the AZM in a strong arc, either hooked or curled. This development is associated with a pair of strong undulating membranes. Macronucleus in two parts each with a micronucleus. Several species have been described.
Borror (1972) and Jankowski (1979) submerge this genus in Oxytricha.
Quote; Colin R. Curds, Michael A. Gates and David McL. Roberts "British and other freshwater ciliated protozoa Part II Ciliophora: Oligohymenophora and Polyhymenophora" Cambridge University Press, 1983 (ref. ID; 2014)
[ref. ID; 4894]
Improved characterization; Undulating membranes in Steinia pattern. One right and one left row of marginal cirri, distinctly separate posteriorly. Caudal cirri present. Six dorsal kineties. Primordia V and VI of the proter and opisthe originate from postoral ventral cirrus V/4. Dorsal morphogenesis in Oxytricha pattern. (ref. ID; 4894)
Remarks; By non-specialists in vivo easily confused with Cyrtohymena because the large buccal cavity is transparent in both genera. However, Cyrtohymena lacks the small pit in the buccal cavity and usually has a more flexible body. (ref. ID; 4894)
Type species (subsequent designation by Foissner 1989); Oxytricha platystoma Ehrenberg, 1831 (ref. ID; 4894)