High genetic divergence but low morphological differences in a keelback snake Rhabdophis subminiatus (Reptilia, Colubridae)

Integrative taxonomy based on multiple data sets plays an important role in species classification, especially in the case of cryptic species. Rhabdophis subminiatus is a colubrid snake with broadly geographical distribution, and two subspecies (Rhabdophis subminiatus subminiatus and Rhabdophis subminiatus helleri) are currently recognized within this species. Based on external morphological comparison, mitochondrial DNA (mtDNA)-based phylogeny, single-nucleotide polymorphism (SNP)-based phylogeny, and population structure analysis, we explored the intraspecific taxonomy of R. subminiatus. Phylogenetic analysis based on mtDNA and SNPs consistently uncovered two highly supported lineages separated by a large genetic distance, with SNP-based principal component analysis (PCA) and population structure analysis displaying similar results. Despite the fact that PCA based on morphological data did not show population differentiation, unlike the molecular data, we suggest that R. s. helleri should be elevated to the specific rank as Rhabdophis helleri based on all lines of evidence. The distributional boundary between the two species R. helleri and R. subminiatus is tentatively proposed.

Automated summary

Integrative taxonomy based on multiple data sets is crucial for species classification, especially for cryptic species. Through analysis of external morphology, mtDNA-based phylogeny, SNP-based phylogeny, and population structure, researchers identified two distinct lineages within Rhabdophis subminiatus and proposed elevating R. s. helleri to a separate species Rhabdophis helleri, with a tentative distributional boundary proposed between the two species.