Taxonomic reassessment of Achalinus jinggangensis (Zong & Ma, 1983) (Serpentes, Xenodermidae), with description of a new species from Zhejiang Province, China

The taxonomy of Achalinus jinggangensis has long remained unclear due to limited sampling and the consequent lack of publicly available molecular and distributional data. Here, we re-evaluate the taxonomic status of A. jinggangensis using an integrative approach that combines molecular phylogenetic analyses, detailed morphological comparisons, and direct examination of type material, and provide a comprehensive redescription of this species.

In addition, we describe an unexpected new species from Kuocang Mountain, Linhai City, Zhejiang Province, China, Achalinus mirabilis sp. nov. Phylogenetic analyses indicate that Achalinus mirabilis sp. nov. appears to be most closely related to A. jinggangensis, although this relationship is not statistically supported, and exhibits substantial genetic divergence, as indicated by uncorrected p - distances of 9.5 % – 10.9 % in the CO 1 gene fragment.

Morphologically, the new species is readily distinguished from A. jinggangensis by its distinctly keeled outermost dorsal scale row, a higher number of ventral scales in both sexes, and conspicuous differences in coloration. Our results highlight previously underestimated species diversity within Achalinus and refine the current understanding of its taxonomy. This study increases the number of recognized species in the genus Achalinus to 30, and underscores the importance of integrative approaches in resolving cryptic diversity and taxonomic complexity within the genus.