Evolution Of The African Slippery Frogs (Anura:Conraua), Including The World'S Largest Living Frog

AlthoughConraua goliathis well known as the largest living frog species, the diversity and evolution of the genusConrauaacross sub-Saharan Africa remain poorly understood. We present multilocus phylogenetic analyses of the six currently recognized species that provide insights into divergence times, biogeography, body size evolution and undescribed species. An analysis of divergence times demonstrates that crown-groupConrauaarose some time during the latest Oligocene to mid-Miocene followed by divergence into major lineages in the mid-Miocene that may reflect the fragmentation of widespread tropical forests in Africa that began at this time. We find three pairs of sister species,C. crassipes + C. beccarii,C. alleni + C. derooiandC. goliath + C. robusta, each of which diverged during the Miocene. These relationships reject phylogenetic hypotheses based solely on biogeography as the geographically peripheralC. beccariifrom north-eastern Africa is nested within western African species and the Central African species do not form a clade. Our species delimitation analyses provide support for undescribed species inC. alleni,C. beccariiandC. derooi, and possiblyC. crassipes, suggesting that the current taxonomy substantially underestimates species diversity. There is no clear directional trend of either increasing or decreasing body size inConrauaand the three largest species do not form a clade. With a robust phylogenetic hypothesis in hand, further field-based studies are needed to understand the evolution of morphology and life history in this charismatic African anuran clade.