Taxonomic reassessment and color-pattern polymorphism of the Oriental fire-bellied newt Hypselotriton orientalis (Urodela, Salamandridae)

The Oriental fire-bellied newt Hypselotriton orientalis, widely distributed in eastern China, has long faced taxonomic ambiguities. Although the nominate subspecies of H. orientalis and the other subspecies, H. orientalis qianshan, are known to exhibit geographic segregation, the taxonomic status and distribution pattern of these two groups remain unverified by integrated evidence and comprehensive sampling. In addition, the color-pattern polymorphism of this newt is poorly studied.

Herein, based on extensive geographic sampling (128 samples, 19 localities), morphological examination, and phylogenetic analysis of mitochondrial NADH dehydrogenase subunit 2 (ND 2) gene fragments, we elevate the Dabie Mountain region subspecies to distinct-species status as H. qianshan stat. nov., and reassess its distribution range. Morphologically, this newly ranked taxon distinctly differs from H. orientalis orientalis by its smaller body length ratios (TOL / SVL and TAL / SVL), smaller fore-limb length ratio (FLL / SVL); longer internasal distance in males, longer interorbital distance in females; rust-red or rust-white patches on the dorsum; discontinuous dorsal ridge lines; the presence of orange-red patches on finger I; discontinuous or absent black stripes on the venter; and relatively inconspicuous vertebral ridge.

Molecularly, the newly ranked taxon forms an independent clade with strong support (1.00 / 99) in the phylogenetic trees; the uncorrected group mean genetic distance between the newly ranked taxon and H. orientalis orientalis was 3.5 %. Geographically, the newly ranked taxon and H. orientalis orientalis are separated by the Yangtze River, Luoxiao Mountains, Jiuling Mountains and Mufu Mountains. The number of species in the genus Hypselotriton now reaches 12.

Meanwhile, we further report on the intraspecific color-pattern polymorphism of H. orientalis sensu lato. The potential species richness and color-pattern polymorphism in salamanders deserves further attention.