Integrative Morphological and Genetic Characterisation of the Fish Parasitic Copepod Ergasilus mirabilis Oldewage & van As, 1987: Insights into Host Specificity and Distribution in Southern Africa

Abstract

Ergasilids are external parasites typically found on the gills and fins of their hosts. In Africa, 19 species of Ergasilus von Nordmann, 1832 are reported. Of those, Ergasilus mirabilis Oldewage & van As, 1987 is one of the least host-specific, with a wide distribution range in southern Africa. As with most species in the genus, genetic data are not available to support the morphological placement of this species within the genus. Specimens representing E. mirabilis were obtained from the gills of Clarias gariepinus (Burchell, 1822) collected from several localities in South Africa and Zambia. Fish were dissected and gills screened using standard techniques. Following a comprehensive morphological study using light and scanning electron microscopy, additional morphological characters are reported. Furthermore, novel data on partial 18S, 28S (rRNA), and COI (mtDNA) gene regions are presented. This is the first integrative study on the morphology of E. mirabilis with supporting genetic data, as well as new distribution records from the KuShokwe Pan in the Phongolo River floodplain and the Vaal River in South Africa, and from the Barotse floodplain in Zambezi River, Zambia. An updated overview is provided for the species of Ergasilus from Africa, including hosts, distribution, and genetic information.