Diversity of Ridged Frogs (Ptychadenidae: Ptychadena) in the easternmost remnant of the Guineo-Congolian rain forest: an analysis using morphology, bioacoustics and molecular genetics

We studied taxonomic diversity of Ridged Frogs, genus Ptychadena, in the Kakamega Forest, western Kenya. It is the easternmost relict of a former continuous Guineo-Congolian rain forest belt which continuously existed in the past. Based on morphometrical and non-morphometrical morphology adult characters and using information obtained from male advertisement calls as well as sequences of the mitochondrial 16S rRNA gene, we distinguish five syntopic species. Standardized diagnoses with 35 characters are provided for each. In the absence of a taxonomic revision of the genus Ptychadena and because we did not use comparative material from elsewhere, we only provisionally allocate species names to the taxa identified by us and discuss available names on the basis of comparisons with bioacoustic and molecular data from other regions. The power of characters defining Ptychadena species and the value of different methodical approaches are discussed, especially important for rapid and easy field identification for conservation purposes. Furthermore, we provide evidence that Ptychadena has independently colonised the Kakamega Forest from or via the Congo basin, as well as East and South Africa.