Molecular and morphological evidences for considering Rhabdophis guangdongensis Zhu, Wang, Takeuchi & Zhao, 2014 a junior synonym of Rhabdophis angeli (Bourret, 1934) (Squamata: Natricidae)

We report the rediscovery of the keelback snake Rhabdophis angeli (Bourret, 1934) from its type locality in Tam Dao National Park, Phu Tho Province, Vietnam, nearly 90 years after its original description. Based on an integrative approach combining morphological examination and molecular phylogenetic analyses, we revise the diagnosis of Rhabdophis angeli and formally synonymise Rhabdophis guangdongensis Zhu, Wang, Takeuchi & Zhao, 2014, with R. angeli. Given the current distributional data, made of widely scattered localities, and the presence of potential threats, we recommend that Rhabdophis angeli be categorised as Near Threatened (NT) under the IUCN Red List criteria. This study highlights the importance of comprehensive taxon sampling, particularly in adjacent regions, to improve our understanding of species boundaries and conservation status. An updated identification key is provided for species within the Rhabdophis nuchalis group, highlighting the need for further integrative taxonomic work in this complex.