An unidentified monogenean diplozoid species was collected from the gills of moggel in the Vaal River and Vaal Dam, South Africa. Specimens were removed from gills of the hosts and observed using light and electron microscopy to compare these diplozoids with known species. The second internal transcribed spacer (ITS2) of the ribosomal gene was amplified, sequenced and compared to that of other diplozoid taxa. Morphological species delimitation was used to determine the identity of these diplozoids, but they did not match the description of any diplozoid taxa. This species is recognized by the specific size of the hooks, number of plicae in posterior and trapezoid anterior projection of the median sclerite connecting to the clamp jaws via a single sclerite, occasionally with two small additional sclerites. Genetic characteristics based on sequence data from the ITS2 region also distinguish this taxon from all other diplozoid taxa. This South African diplozoid grouped in the same clade as Paradiplozoon ichthyoxanthon Avenant-Oldewage, 2013. Data clearly indicate that diplozoids collected from moggel represent a new, distinct taxon of Paradiplozoon Akhmerov, 1974 and are described here as Paradiplozoon vaalense n. sp.