Main Content

The World of Protozoa, Rotifera, Nematoda and Oligochaeta

[ref. ID; 4335 (John C. Clamp, 1991)]

Family Usconophryidae n. fam. Clamp, 1991


Loricate, sessiline peritrichs that exist as solitary or paired zooids. Lorica either hemispheroidal or urceolate. Peristome of operculariform type: peristomial lip rigid and noneversible; epistomial disk retracted by a cylindrical column of myonemes not arising from cortex of cell. Edge of peristomial lip not associated with lorica aperture; entire body able to contract within lorica. Lorica aperture not provided with closure apparatus (either lips or operculum) operated by contraction of peristomial sphincter. Oral pole of body displaced laterally and body flattened in some; others with radially symmetrical, undistorted bodies. Stalk absent in known members; trophont attaches to substrate by adoral surface of lorica. Telotroch forms on right side (when viewed from above) of parent in flattened, distorted members.


The Usconophryidae n. fam, differs from the Lagenophryidae by its lack of an actively operated closure apparatus for the lorica aperture, which is uniformly characteristic of the latter. Flattened usoconophryids (genus Usconophrys) also differ from lagenophryids in the polarity of the lateral displacement of their oral end. Using the position of telotroch formation as a landmark, it can be seen that lagenophryids and flattened usconophryids are distorted in opposite directions. The apparent similarities between Usconophrys and lagenophryids are purely superficial, having arisen by convergent evolutionary paths. The Usconophryidae resembles the Family Operculiariidae Corliss, 1979 in the structure of the peristome but differs from it in possessing a complete (i.e. true) lorica that encloses the entire body. Possession of a complete lorica is also a defining characteristic of the Vaginicolidae de Fromental, 1874 and Rovinjellidae Matthes, 1972: however, both of these families have an epistyliform type of peristome fundamentally different from the operculariform peristome of the Usconophryidae.

Type genus

Usconophrys Jankowski, 1985

Usconophrys Jankowski, 1985

Cyclodonta Matthes, 1958. Cyclodonta has been assigned to both the Lagenophryidae (Corliss 1961) and Vaginicolidae (Corliss 1979) since its description (Matthes 1958), but it more properly belongs in the Usconophryidae because of its operculariform peristome, complete lorica, and lack of a lagenophryid-type closure apparatus for the lorica aperture.