Redescription of Pleorchis polyorchis (Stossich, 1889) (Digenea: Acanthocolpidae), a rare and poorly known parasite of the intestine of Sciaena umbra l. (Perciformes: Sciaenidae) from the western Mediterranean Sea.

Pleorchis polyorchis (Stossich, 1889), the type-species of the genus, is described on the basis of new material from Sciaena umbra from off Corsica, France. This is only the second description of this species. The results of this study indicate that there are apparent errors in the original description in relation to the number of testes, the anterior limit of the vitellarium, the extent of the post-testicular field and the shape of the intestinal caeca, and that the type-species is closer to its congeners than previously believed. P polyorchis is compared with other nominal species of the genus, and species previously attributed to the genus are commented upon.