Revalidated after having been described more than a century ago: Calamaria berezowskii Günther, 1896 (Squamata, Colubridae) from Sichuan, Southwestern China

The reed snakes of the genus Calamaria Boie, 1827 are one of the largest groups of Asian snakes, distributed from northeast India to the Maluku Islands of east Indonesia. Recent research on the genus in China has revealed that the species diversity of the group was underestimated. In this study, morphological comparisons and mitochondrial DNA analysis revealed that a junior synonym of C. pavimentata Duméril, Bibron & Duméril, 1854 — Calamaria berezowskii Günther, 1896 is valid, hence we redescribed and recovered the validity of C. berezowskii. This species can be distinguished from other congeners by the combination of the following characters: four supralabials; one preocular; rostral shield width larger than height; mental not touching anterior chin shields; eye diameter less than the distance from eye to mouth edge; less than 1/2 of the posterior chin shield meets in the midline; dorsal scales reduced to six rows at tail; indistinct light ring present in the nuchal region or a more or less distinct yellowish collar. Phylogenetically, this species is sister to C. pavimentata, with significant genetic differences (0.190) on mitochondrial gene Cyt b.