In this study, supplementary information on the morphology of the siphonostomatoid copepod Lepeophtheirus acutus Heller, 1865 is given based on new material collected from the ventral body surface and mouth cavity of common guitarfish, Rhinobatos rhinobatos (Linnaeus) and from the branchial cavity of bull ray, Aetomylaeus bovinus (Geoffroy Saint-Hilaire) caught in Iskenderun Bay, Turkey. This is the first report of L. acutus from Mediterranean waters. Key diagnostic characters of both sexes are reported, supported by light and scanning electron microscopy observations. In addition, Lepeophtheirus rhinobati Luque, Chaves et Cezar, 1998, which is closely related to L. acutus and has been reported from the same host genus, Rhinobatos, is reexamined based on paratypes stored in the collections of the United States National Museum of Natural History. Some of the key diagnostic characters which were incompletely known or lacking in the original description of both sexes of L. rhinobati are redescribed and/or presented for the first time.