A new species of cascade frog (Anura: Ranidae: Amolops) from central Yunnan, China.

A new species of the genus Amolops, Amolops ailao sp. nov., is described from central Yunnan, China. The new species belongs to the A. mantzorum species group. Phylogenetic analyses based on the combination of mitochondrial 16S rRNA, COI, and cytb genes revealed that the new species is the sister taxon to Amolops ottorum with strong support. Genetically, the new species differs from A. ottorum by 5.0% in cytb sequences. Morphologically, the new species can be distinguished from known congeners by the combination of the following characters: true dorsolateral folds absent, but dorsolateral folds formed by series of glands present; circummarginal groove on tip of first finger absent; body size small (males SVL 33.0-35.1 mm and female SVL 41.3 mm); HW/SVL 0.32‒0.35; UEW/SVL 0.08‒0.10; THL/SVL 0.52‒0.56; vomerine teeth absent; interorbital distance narrower than internarial distance; tympanum distinct, less than half eye diameter; supratympanic fold present, indistinct; a pair of large tubercles on sides of cloaca; tibiotarsal articulation reaching beyond anterior corner of eye; and vocal sac absent. The cladogenesis events within the A. mantzorum group rapidly occurred from Pliocene 4.23 Mya to Pleistocene 1.2 Mya, coinciding with the recent intensive uplift of the Qinghai-Tibetan Plateau since the Pliocene. Combining findings in this study with the most recent taxonomic progress, we consider that there are 20 known Amolops species in Yunnan, China, accounting for the highest proportion of amphibian diversity of Yunnan, and five of them belong to the A. mantzorum group. Among different subfauna and water systems in Yunnan, the species diversity of Amolops in northwestern Yunnan and Nu River Basin is highest.