Thesis (Ph.D. (Zoology)) --University of Limpopo, 2021 / The present study was conducted to evaluate the morphological and molecular characterisation of species of Dactylogyrus parasitising Enteromius spp. from the Limpopo River System, South Africa. In addition, the study was intended to establish host-parasite associations from this system. A total of 95 host specimens were collected from eight localities between 2015 and 2016 within the Limpopo River System. Fish hosts were collected using gill nets, seine nets, fyke nets, and an electric shocker. From these, three host species were identified, E. afrohamiltoni, E. unitaeniatus, and E. trimaculatus where after monogenean parasites were retrieved from the gills using stereo microscopes. Morphometric analysis of the haptoral hard parts and male copulatory organs were studied for species identification, supported by nuclear ribosomal DNA sequences of the partial 18S rDNA region and the entire ITS-1 and partial 5.8S rDNA region, and the partial 28S rDNA region. Examination of E. afrohamiltoni revealed the presence of D. afrohamiltonii which is the first record of a monogenean parasite from this host. In addition, E. unitaeniatus revealed the presence of two species of Dactylogyrus: D. letabaensis and D. limpopoensis which are the first record of monogenean parasites from this host. The remaining Dactylogyrus species were retrieved from E. trimaculatus, namely, D. afrolongicornis, D. allolongionchus, and D. myersi. Enteromius trimaculatus harboured five of the species retrieved. The two species, D. afrolongicornis and D. allolongionchus were the most abundant from six of the eight localities studied, followed by D. myersi abundant in five of the eight localities. Dactylogyrus afrohamiltonii was considered a strict specialist, while the remaining species were considered to be intermediate specialists. Forty-one sequences of the partial 18S rDNA and the entire ITS-1 and partial 5.8S rDNA region and 19 sequences of the partial 28S rDNA region of Dactylogyrus species, including Pseudodactylogyrus anguillae were included to reconstruct the phylogenetic relationships. Based on this, molecular analysis of D. afrolongicornis from Enteromius hosts were recorded for the first time for the combined 18S rDNA and the entire ITS-1 and partial 5.8S rDNA region. The analysis revealed several groupings of Dactylogyrus species inferred largely from European cyprinoids and corresponded to host specificity. From the partial 28S rDNA, three clades were revealed linked to their biogeographical regions. Phylogenetic analysis from the 28S rDNA suggests that D. aspili from E. macrops and D. afrolongicornis are closely related. / National Research Foundation (NRF) and DST Innovation Scholarship and the Vlaamse Interuniversitaire RaadUniversity Development Corporation (VLIR-UOS)