Diversity of Quadriacanthus (Monogenea: Dactylogyridae) in the Upper Congo Basin: new geographical records and description of five new species from the gills of Clarias ngamensis (Siluriformes: Clariidae)

Abstract

Monogenean parasites belonging to Quadriacanthus have never been reported from Clarias ngamensis, but are commonly found on congeners. In view of the specificity of monogeneans, the genetic proximity and the co-occurrence of C. ngamensis and C. gariepinus in Africa, it is hypothesised that a parasitological survey of C. ngamensis will yield several species of Quadriacanthus as its congeneric host C. gariepinus harbours these parasites. The present study aims to explore the monogenean parasites from the gills of C. ngamensis in the Upper Congo Basin by (i) inventorying their diversity and providing their morphological characterisation, and (ii) analysing their infection parameters. Monogeneans were isolated from the gills, and identified based on morphological analysis of genital and haptoral sclerotized parts. Seven parasite species belonging to Quadriacanthus were found. Among them, two species, Q. aegypticus and Q. allobychowskiella, are both newly reported in the Upper Congo Basin and newly recorded on C. ngamensis. Quadriacanthus amakaliae sp. nov., Q. halajiani sp. nov., Q. domatanai sp. nov., Q. lubandaensis sp. nov., and Q. curvicirrus sp. nov. are new to science and described herein. The most prevalent parasite species was Q. curvicirrus sp. nov. in the Luapula River (prevalence = 66.7%) with mean infection intensity of 6.3 +/- 5.8. Quadriacanthus allobychowskiella and Q. aegypticus are known parasites from C. gariepinus and their presence on C. ngamensis is probably the result of lateral transfers. The discovery of five new species from C. ngamensis highlights the parasite diversity still to be explored in the region.