Parasitological examination of freshwater fishes of the Phongolo River in north-eastern KwaZulu-Natal, South Africa resulted in the discovery and morphological and molecular characterisation of a new species of Wenyonia Woodland, 1923 (Cestoda: Caryophyllidea). The new species from the plain squeaker, Synodontis zambezensis Peters (Siluriformes: Mochokidae), is morphologically most similar to Wenyonia acuminata Woodland, 1923, a species reported from three species of Synodontis in north-eastern, western and central Africa (Sudan, Nigeria, Democratic Republic of the Congo). Both these species are markedly different from congeners by having a nematoform body and a digitiform scolex. Wenyonia gracilis sp. n. differs from W. acuminata in its general body size, length and width of main body regions (testicular and uterine regions), a posterior extension of the testes into the uterine region, numerous postovarian vitelline follicles filling the entire medulla, eggs c. 1/3 larger in size, and a scolex with an apical introvert but devoid of longitudinal furrows and a well-defined base. Wenyonia gracilis is the seventh species in the genus and the first autochthonous caryophyllidean ever reported and described from southern Africa (south of the Zambezi River).
Keywords: South Africa; Tapeworms; biodiversity; biogeography; fish parasites; molecular characterisation; new species; taxonomy.