First record from the southern hemisphere: significant range extension, new host record and molecular characterisation of <i>Ligophorus minimus</i> Euzet et Suriano, 1977 (Monogenea: Dactylogyridae)

The gill monogeneans from the genus <i>Ligophorus</i> Euzet et Suriano, 1977 are parasites strictly host specific to mugilid fishes, occurring on a number of mullet species. In South Africa, monogeneans from marine and estuarine teleost fishes are still poorly known. During 2020, five individuals of the South African mullet <i>Chelon richardsonii</i> (Smith) were collected from the Groot River estuary on the south coast of South Africa (south-western Indian Ocean). Monogeneans collected from the gills were preserved for morphological and phylogenetic analyses. The monogeneans found were morphologically identified as <i>Ligophorus minimus</i> Euzet et Suriano, 1977. This study provides the first record of <i>L. minimus</i> from South Africa and the first record on the host <i>C. richardsonii</i>. Furthermore, sequences of the partial 28S rRNA gene and the entire ITS1 region for this species were obtained from the sampled locality in the south-western Indian Ocean for the first time. Phylogenetic analyses confirmed the morphological identification of <i>L. minimus</i> in the present study. The phylogenetic relationships of <i>L. minimus</i> with its congeners corroborate previous studies, providing more insights into the monophyly of the genus, routes of new host colonisation, and distribution patterns.