Taxonomic Status of Tetraophasis obscurus and Tetraophasis szechenyii (Aves: Galliformes: Phasianidae) Based on the Complete Mitochondrial Genome

Tetraophasis szechenyii and T. obscurus are endangered phasianid birds endemic to China. Historically, the question of whether T. obscurus and T. szechenyii are valid species or subspecies has been controversial. In order to clarify their phylogenetic relationship, we sequenced the complete mitochondrial genome of T. obscurus and, using the complete mitochondrial genome of T. szechenyii, which our lab had already sequenced, conducted Bayesian and maximum-likelihood phylogenetic analyses based on the sequences of 12 concatenated heavy-strand encoded protein-coding genes. Genetic distance and divergence time between the two species were also calculated. The complete mitochondrial genome of T. obscurus was 16,707 bases (accession no.: NC_018034), and its structure was similar to mitochondrial genomes reported for other phasianids. The genetic distance between T. obscurus and T. szechenyii was 0.028, and the divergence time of T. obscurus and T. szechenyii was 1.75 Myr. Considering the genetic distance and divergence time, as well as geographical distribution and morphological differences, we suggest that T. obscurus and T. szechenyii are two valid species. The Pleistocene glacial events in the Hengduan Mountains region may have played an important role in the speciation of T. obscurus and T. szechenyii.