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During a parasitological survey carried out between May and August 2022 in the River Nyando, Lake Victoria Basin, a single species of Rhabdochona Railliet, 1916 (Nematoda: Rhabdochonidae) was recorded from the intestine of the Rippon barbel, Labeobarbus altianalis (Boulenger, 1900) (Cyprinidae). Based on light microscopy (LM), scanning electron microscopy (SEM) and DNA analyses the parasite was identified as Rhabdochona (Rhabdochona) gendrei Campana-Rouget, 1961. Light microscopy, SEM and DNA studies on this rhabdochonid resulted in a detailed redescription of the adult male and female. The following additional taxonomic features are described in the male: 14 anterior prostomal teeth; 12 pairs of preanal papillae: 11 subventral and one lateral; six pairs of postanal papillae: five subventral and one lateral, with the latter pair at the level of first subventral pairs when counted from the cloacal aperture. For the female: 14 anterior prostomal teeth and the size and absence of superficial structures on fully mature (larvated) eggs dissected out of the nematode body. Specimens of R. gendrei were genetically distinct in the 28S rRNA and cytochrome c oxidase subunit 1 (cox 1) mitochondrial gene regions from known species of Rhabdochona. This is the first study that provides genetic data for a species of Rhabdochona from Africa, the first SEM of R. gendrei , and the first report of this parasite from Kenya. The molecular and SEM data reported herein provide a useful point of reference for future studies on Rhadochona in Africa. [Display omitted] • Redescription of Rhabdochona gendrei from Labeobarbus altianalis. • The first study providing genetic data for a species of Rhabdochona from Africa. • This is the first scanning electron microscopy study of R. gendrei. • First report of R. gendrei from Kenya. • Findings herein provide useful point of reference for future studies on Rhadochona. [ABSTRACT FROM AUTHOR]

Clarias gariepinus (Burchell) is one of several freshwater fish species that have been translocated beyond its natural geographic range in South Africa. The present study investigated the parasitic communities of two translocated populations (one in the Riviersonderend River, Western Cape and the other from the Great Fish River, Eastern Cape) as well as its native source population from Gariep Dam, Free State. A total of nine, seven, and eight parasitic taxa were found to parasitise various organs of C. gariepinus from the three populations, respectively. The diversity and abundances of parasitic species in the two translocated populations were similar, but distinct community assemblages were observed. Parasite community composition from the Great Fish River was similar to that of the source population from Gariep Dam, whereas the parasitic community from C. gariepinus in the Riviersonderend River was distinct from that of Gariep Dam. This, together with the introduction history into the Western Cape, suggests that translocated C. gariepinus is sourced from various systems across South Africa, or that suitable intermediate hosts are present in the recipient ecosystems to sustain host-specific co-introduced parasitic taxa of C. gariepinus. In total, the resilience of 11 specialist parasite species of C. gariepinus is demonstrated in their persistence upon co-introduction into the two novel environments with their host, and support for the enemy release hypothesis is confirmed in the loss of known parasite taxa in translocated populations. The presence of the co-invasive fish lice Argulus japonicus Thiele, 1900 is reported from C. gariepinus in Gariep Dam and the Asian tapeworm Schyzocotyle acheilognathi (Yamaguti, 1934) was found from translocated C. gariepinus in the Riviersonderend River, Western Cape and lastly, a suspected case of parasite spillback from an unknown native host is reported. [Display omitted] • Distinct parasitic communities were observed between native and translocated populations of C. gariepinus in South Africa. • Parasite community richness was not significantly different between native and translocated populations. • Similar infracommunity assemblages between Great Fish River and Gariep Dam, but unique parasite communities present. • Introduction history and distinct parasite community assemblages suggest multiple source populations for translocated populations in the Western Cape. • Presence of alien invasive parasite, the Asian tapeworm Schyzocotyle acheilognathi confirmed. [ABSTRACT FROM AUTHOR]

Four species of previously known nematodes from the family Camallanidae were found from different hosts in South Africa: Batrachocamallanus xenopodis from the frog Xenopus muelleri , Paracamallanus cyathopharynx and Procamallanus pseudolaeviconchus from the catfish Clarias gariepinus and Spirocamallanus daleneae from the catfish Synodontis zambezensis. In the material collected from various marine fishes, several specimens of nematodes from the genus Camallanus clearly differed from all previously known species. Based on morphological differences these specimens are assigned to a new species, C. sodwanaensis. Molecular data of 18S and 28S rDNA and COI sequences are provided for the collected species and a phylogenetic analyses based on 28S gene fragmets are presented. Image 1 • Five species of Camallanidae nematodes found from different hosts in South Africa. • Camallanus sodwanaensis n. sp. is the first species from marine fish in Southern Africa. • Molecular data of 18S and 28SrDNA and COI sequences provided for found species. • Phylogenetic analyses based on 28S gene fragmets is performed. [ABSTRACT FROM AUTHOR]