Family OPERCULARIIDAE Fauré-Fremiet, n. fam. by Corliss 1979.

Generally with stalk, noncontractile; solitary or colonial, with highly developed theca in many species; epistomial disc has characteristic appearance of an operculum at anterior end of body; found very commonly as epibionts on fresh-water insects or other arthropods, but one species (Operculariella) is endocommensal in esophagus of a beetle and another (Orsomia) associated with an oligochaete annelid.

[Lom had suggested that Fauré-Fremiet - on the basis of unpublished notes seen by Lom - should be credited with this family: Jankowski (1975), working independently, has recently proposed the same name for the group, but provided no description or characterization.]

Ballodora Dogiel & Furssenko, 1921. Few species.
Heteropolaria Foissner & Schubert, 1977. Single species.
Opercularia Goldfuss, 1820 (syn. Cochlearia p.p., Discotheca, Kindella). Very many (perhaps 100?) species.
Operculariella Stammer, 1948. Single species.
Orbopercularia Lust 1950. Very many (ca. 50) species.
Propyxidium n. n. (for Pyxidiella Corliss, 1960 [for Pyxidium]; syn. Cochlearia p.p.). Many species.
Incertae sedis:
Orsomia Baer, 1952. Single species.

[Corliss´ 1960 replacement name for Kent's venerable, but preoccupied, Pyxidium was, it turns out, preoccupied itself by Pyxidiella Cookson & Eisenack, 1958, a protistan fossil of unknown affinities. Thus a second new name is required. For the many included species in their new combination, see Corliss' (1960b) list, substituting Propyxidium for Pyxidiella (with appropriate changes in endings of specific epithets); type-species, P. cothurnoides (Kent, 1882) Corliss 1979]