Observations on the peritrichous ciliate Scyphidia ubiquita from the west coast of Wales and a description of a new species

Abstract

The peritrichous ciliate, Scyphidia ubiquita Hirshfield has been recorded on the west coast of Wales from the mantle cavity of snails belonging to the genus Littorina. The ultrastructure is similar to that described for specimens from the Pacific coast of the United States, but the scopula lacks a pellicular crest. Scyphidia acanthophorasp.n. from the mantle cavity of the top shells, Gibbula umbilicalis (da Costa) and Monodonta lineata (da Costa) is described on the basis of light, surface and transmission electron microscopy. It is distinguished from other scyphidians principally by the general body shape, form of the macronucleus and the ultrastructure of the scopula disc. Comparisons are made between this species and S. ubiquita particularly with respect to the ultrastructure of the scopula and the mode of attachment to the host.