A new species, Primulina cataractarum (Gesneriaceae) from limestone areas in southern Hunan, China, is described and illustrated with photographs based on morphological and molecular data. This new species is slightly similar to P. porphyrea and P. rubribracteata in morphology, but it can be easily distinguished by its smaller rounder leaves, large repand green bracts and purple corolla tube. Phylogenetic analysis proved that these three species are different, and their relationships are relatively distant. It also reveals that P. cataractarum is genetically similar to P. jiangyongensis, which is geographically next to the type locality of the new species, but they differ greatly in morphology. Following the IUCN Red List Criteria, P. cataractarum is assessed as Critically Endangered (CR B2a; C2b) because of its limited populations and vulnerable habitat.