Morphology and Stomatogenesis of Mesanophrys pugettensis n. sp. (Scuticociliatida: Orchitophryidae), a Facultative Parasitic Ciliate of the Dungeness Crab, Cancer magister (Crustacea: Decapoda)

A ciliate was encountered in the blood of laboratory-held and wild Dungeness crabs, Cancer magister, over an eight-year period. Several silver-staining methods were applied to the ciliate to reveal both its morphology and stomatogenesis. It was found to be morphologically similar to previously reported, but as yet undescribed, histophagous ciliates of crustaceans from both the Atlantic and Pacific North American Coasts. The ciliate was determined to be an undescribed species of the recently created genus Mesanophrys, possessing three characteristic oral polykinetids, an oral dikinetid primarily composed of a "b" segment, and an oral dikinetid "c" segment. Early in stomatogenesis, a fourth transitional ciliary field occurs, suggesting that the first oral polykinetid (OPK1) is composed of two different but functionally related segments. This paper describes Mesanophrys pugettensis as a new species and discusses its relationship with other crustacean ciliates of the family Paranophryidae. However, because of a recent addition to the family and the systematic rule of priority, the family Paranophryidae is a junior synonym of the taxon Orchitophryidae.