Description of three new species of Protoancylodiscoides (Monogenea: Dactylogyridae) and biogeography of those parasitizing Chrysichthys nigrodigitatus (Siluriformes: Claroteidae) in Sanaga and Dibamba rivers, Cameroon

Abstract

Chrysichthys nigrodigitatus (Lacépède) specimens were sampled in the Sanaga River and in the Dibamba River. Three new species, Protoancylodiscoides edeaensis sp. nov., P. yombai sp. nov. from both rivers, and P. dibambaensis sp. nov. from the Dibamba River alone, are described. Protoancylodiscoides edeaensis sp. nov., close to P. mansourensis El-Naggar, 1987 and P. chrysichthes Paperna, 1969 by the morphology of the haptor sclerotised parts, differs from these species by the penis length and the morphology of the vagina. Protoancylodiscoides yombai sp. nov. is close to P. edeaensis sp. nov., P. mansourensis, and P. chrysichthes by the morphology of some sclerotised parts of the haptor (ventral bar, ventral anchors, dorsal onchium and hooks). However, it differs from these species by the morphology of the vagina, of the outer root of the dorsal anchor, and the size of some sclerotised parts (dorsal anchor total length, dorsal bar length, ventral anchor length, and penis length). Protoancylodiscoides dibambaensis sp. nov. is close to P. ivoiriensis Bouah, N’Douba & Pariselle, 2021 by the lack of the onchium and the morphology of some sclerotised parts of the haptor. However, it differs from this species by the morphology of the dorsal bar, penis length, dorsal bar length, and of the ventral anchor total length. This study on monogeneans raises the question of ichthyofauna exchange between adjacent streams; it also reveals a longitudinal gradient of Protoancylodiscoides species richness in the Sanaga River.