Review of African Diplozoidae

The family Diplozoidae Palombi, 1949 comprises host specific worms found on the gills of cyprinid fish. Diplozoids are the only members of the Monogenea characterised by a unique monogamous life style where two hermaphroditic adults fuse and live in permanent copula. Little is known of the African Diplozoidae fauna and even less of the Southern African fauna, especially when compared to the European and Asian fauna. The taxonomy of this group of parasites contains a great deal of irregularities and confusion on the placement of species in certain genera. To date two species of Paradiplozoon Achmerov, 1974 are known from Northern Africa, i.e. P. aegyptensis (Fischtal & Kuntz, 1963) collected from Labeo spp. and P. ghanense (Thomas, 1957) described from Alestes spp. Afrodiplozoon polycotyleus (Paperna, 1973), previously of the genus Neodiplozoon Tripathi 1959, was described from Labeo victorianus Boulenger, 1901 in Kenya and from Barbus spp. in Uganda and South Africa. During the present study, it was attempted to clarify the taxonomic disorder and give a review of the African diplozoid fauna. Members of the Diplozoidae were collected from eight cyprinid fish species during fish parasitological surveys over the last 15 years from the Okavango and Orange-Vaal River Systems. Identification of species was mainly done through morphometric analysis. Three different species have been identified belonging to the genera Paradiplozoon, Diplozoon Von Nordmann, 1832 and Afrodiplozoon Khotenovsky, 1980 of which two are newly described species. Paradiplozoon sp. A was collected from Labeo lunatus Jubb, 1963 and Afrodiplozoon polycotyleus from Barbus afrovernayi Nichols & Boulton, 1927, B. multilineatus Worthington, 1933, B. paludinosus Peters, 1852, B. poechii Steindachner, 1911 and B. radiatus Peters, 1853, all from the Okavango River, Botswana. This is also the first records of A. polycotyleus from these hosts. Diplozoon sp. A was collected from Labeo capensis Smith, 1841 and Labeo umbratus Smith, 1841 from the Orange-Vaal River System.