The phylogenetic position of Hyperolius sankuruensis (Anura: Hyperoliidae) reveals biogeographical affinity between the central Congo and West Africa, and illuminates the taxonomy of Hyperolius concolor

African reed frogs (Hyperolius, Hyperoliidae) represent a hyperdiverse genus of arboreal frogs, known for their high intraspecific variation and interspecific similarity. Many recent publications have offered phylogenetic reconstructions and revisions of the genus or specific species groups or complexes. However, there are still many taxa known only from a limited number of localities and collected material that still await molecular evaluation and validation. Among these is H. sankuruensis, a species formally known only from the type locality in the central Congo Basin. The results of our phylogenetic analyses showed this central Congolian taxon to be related to an undescribed species from southwestern Gabon, and unexpectedly to a group of West African species. The West African species also include the widespread H. concolor, which presently comprises three geographically separated subspecies, H. c. concolor occurring west of the Dahomey Gap, H. c. ibadanensis known from Nigeria, and H. c. guttatus from southwestern Cameroon. Species delimitation based on both mitochondrial and nuclear data, together with morphological analyses, found sufficient differences among the three subspecies to elevate them to species status. In addition, the species groups of one of the three major clades within the genus Hyperolius are revised.