From the Atlantic coast to Lake Tanganyika: gill-infecting flatworms of freshwater pellonuline clupeid fishes in West and Central Africa, with description of eleven new species and key to Kapentagyrus (Monogenea, Dactylogyridae)

Unlike their marine counterparts, tropical freshwater clupeids receive little scientific attention. However, they sustain important fisheries that may be of (inter)national commercial interest. Africa harbours over 20 freshwater clupeid species within Pellonulini. Recent research suggests their most abundant parasites are gill-infecting monogenean flatworms within Kapentagyrus. After inspecting specimens of 12 freshwater clupeids from West and Central Africa, mainly sourced in biodiversity collections, we propose 11 new species of Kapentagyrus which we describe using their haptoral and genital morphology. Because of their high morphological similarity, species delineation relies mostly on morphometrics of anchors and hooks. Specifically, earlier, molecular taxonomic work indicated that the proportion between the length of the anchor roots, and between hook and anchor length, are diagnostic. On average, about one species of Kapentagyrus exists per pellonuline species, although Pellonula leonensis harbours four species and Microthrissa congica two, while Microthrissa moeruensis and Potamothrissa acutirostris share a gill monogenean species. This study more than quadruples the number of known species of Kapentagyrus, also almost quadrupling the number of pellonuline species of which monogeneans are known. Since members of Kapentagyrus are informative about their hosts' ecology, evolutionary history, and introduction routes, this enables a parasitological perspective on several data-poor African fisheries.