Five new species of Pseudorhabdosynochus (Monogenea: Diplectanidae) from the gills of Epinephelus costae (Teleostei: Serranidae)

five species differ from each other and from all described species of Pseudorhabdosynochus by the morphology and size of their sclerotized vagina. These diplectanids (except P. sinediscus) were also collected from the same host off Dakar in 1981 and 1989. The present paper includes the descriptions and taxonomic considerations of each of these species in addition to an amended diagnosis of Pseudorhabdosynochus. A key to the five new species parasitizing E. costae is provided. These five species are the first diplectanids described from E. costae. Groupers, Epinephelus spp. (Serranidae: Epinepheli-nae), are mostly found in tropical and subtropical seas. Only 7 of the 99 species described in the genus have been reported from the Mediterranean Sea and the east-ern Atlantic Ocean (Heemstra and Randall 1993). Two species, E. coioides (Hamilton, 1822) and E. malabari