A NEW SPECIES OF METABENEDENIELLA (MONOGENEA, CAPSALIDAE) FROM THE DORSAL FIN OF DIAGRAMMA-PICTUM (PERCIFORMES, HAEMULIDAE) FROM THE GREAT-BARRIER-REEF, AUSTRALIA WITH A REVISION OF THE GENUS

Metabenedeniella parva n. sp. is described from the marine teleost Dia gramma pictum from Heron Island, Queensland, Australia. The type speci es of the genus, Metabenedeniella hoplognathi, is redescribed and the generic diagnosis emended. Metabenedeniella parva differs from M. hopl ognathi in many respects: M. parva is smaller; in M. parva the accesso ry sclerites and anterior hamuli are of similar length, but the poster ior hamuli are smaller, whereas in M. hoplognathi the accessory scleri tes are longer than the anterior hamuli and the anterior and posterior hamuli are of similar length; in M. parva the anterior hamuli span th e distance between accessory sclerites and posterior hamuli and the an terior hamuli overlap the posterior hamuli considerably, but in M. hop lognathi the anterior hamuli partially overlap the posterior hamuli an d do not extend anteriorly to reach the accessory sclerites; a sclerit e close to the common genital aperture in M. parva is absent from M. h oplognathi. The 2 species differ also in some of their soft body parts . Specimens reported previously from the gills of Plectorhynchus chaet odonoides off Okinawa, Japan as M. hoplognathi are considered to be M. parva. The discovery of M. parva from only the dorsal fin of D. pictu m at Heron Island enhances the notion that some benedeniine monogenean s from the body surfaces of fish exhibit strong site specificity.