Calamaria pavimentata Duméril, Bibron & Duméril, 1854 was originally described from Java Island, Indonesia, yet specimens from southern China, particularly Guangxi, have long been referred to this species based on general morphological resemblance. Herein, the taxonomic status of Chinese populations previously referred to as Calamaria pavimentata is re-evaluated using an integrative approach combining morphological data and mitochondrial DNA analyses, based on four specimens from Yangjiang City, Guangdong Province, and Chongzuo City, Guangxi Zhuang Autonomous Region, China. Phylogenetic analyses recover the Chinese specimens as a distinct and well-supported lineage within Calamaria. Notably, the Guangdong and Guangxi populations exhibit a relatively high intraspecific mitochondrial divergence (uncorrected p-distance = 10.78% based on the cytochrome b gene), despite the absence of consistent diagnostic morphological differences. Although mitochondrial DNA data from topotypic C. pavimentata, are currently unavailable, the observed morphological differences, together with the pronounced geographic disjunction between Java and southern China, support the recognition of the Chinese population as a distinct species, herein described as Calamaria similis sp. nov. from Guangdong and Guangxi, China. Detailed morphological examinations reveal that Calamaria similis sp. nov. differs from C. pavimentata and all of its currently recognized synonyms by having higher ventral scale counts in females, fewer subcaudal scales in males (but slightly more in females), a smaller maximum total length in males, and a shorter relative tail length in both sexes. Our results highlight the need for renewed field surveys in Java Island, Indonesia to rediscover C. pavimentata sensu stricto, and emphasize that other populations previously identified as C. pavimentata should be re-evaluated using integrative taxonomic approaches.