Bütschli, 1889
Rather similar to prostomatine gymnostome ciliates. Vestibular ciliature non-complex, derived during fission from terminal portions of somatic kineties. Oral aperture apical in free-living and antapical in endozooic species. Some produce gelatinous lorica. Mostly endocommensal in vertebrate hosts.
Suborder Trichostomatina
Family Plagiopylidae