Redescription and neotype designation of Dopasia formosensis (Kishida, 1930) (Squamata, Anguidae) from Taiwan

The legless anguid lizard Dopasia Gray, 1853 is one of the most secretive and least studied lizard groups. Historically, two Dopasia (Squamata: Anguidae) names have been applied to Taiwanese material: D. harti (Boulenger, 1899), originally described from Fujian, China and characterized by conspicuous bluish dorsal blotches, and D. formosensis (Kishida, 1930), described from Taiwan and reported to lack such markings. Taiwanese specimens were long treated as representing two species until Lin et al. (2003) synonymized D. formosensis with D. harti after finding no consistent molecular or scalation differences, and interpreted the presence/absence of bluish blotches as sexual dichromatism. Because topotypic D. harti was not examined in that study and the original type material of D. formosensis has been lost, the application of these names to Taiwanese populations has remained uncertain. Here, we designate a neotype for D. formosensis and provide a detailed redescription based on vouchered specimens from Taiwan. We present standardized morphometric and meristic datasets, including X-ray-based vertebral counts, and generate new mitochondrial sequences to document genetic variation. With the aim of facilitating repeatable comparisons within the East Asian Dopasia species complex, all measurements and counts are made openly available to support future integrative taxonomic reassessments and to improve nomenclatural stability for this rarely encountered lineage. Taken together with currently available lines of evidence, these results suggest recognizing Dopasia formosensis (Kishida, 1930) as a distinct evolutionary lineage, pending a formal systematic revision of the genus.