Morphological evolution from aquatic to terrestrial in the genus Oreolalax (Amphibia, Anura, Megophryidae)

A phylogeny of 17 species in the genus Oreolalax is reconstructed based on 21 morphological characters from adult specimens, skeleton specimens, tadpoles and eggs. Four species groups are recognized, of which the O.rugosus species group is the most primitive, the O. weigoldi species group is the second, the O. omeimontis species group is the third and the O.pingii species group is the most recently diversified. Based on the evolutional tendency of the morphological characters on the phylogenetic tree, it is proposed that the evolution of tympanum, tympanic annulus, columella, spoon-like cartilage and the web between toes reflect the habit changes from aquatic to terrestrial. Thus, Oreolalax is regarded as one important representative genus to study further the evolution of morphological characters from aquatic to terrestrial.