The leaf beetle genus Suinzona, consisting of over 20 species, is mainly known for species from Southwest China, and its closely related genus Potaninia, with only two species, is widely distributed in South China and upper Southeast Asia. Despite recent morphological studies, the status of these taxa has long been controversial. Here, we investigated the taxonomic status and phylogenetic relationships of the genera Suinzona and Potaninia within Chrysomelinae using molecular, morphological and ecological data. Molecular phylogenetic analysis supported that they should be regarded as distinct genera, which is consistent with morphological evidence, e.g., well-developed/reduced hind wings. Based on combined evidence from examination of larval and adult morphology, host plants and mitochondrial genomes, we demonstrate that P. cyrtonoides should be placed in the genus Suinzona and that specimens from South Korea represent a new species. Suinzona borowieci sp. nov., occurring in narrow strips of habitat, shows high levels of genetic divergence and distantly related host plants between populations. The population differentiation seems to be correlated with its non-functional wings causing reduced dispersal ability and genetic isolation. Several populations have declined dramatically over the last few decades due to loss of habitat and thus are in need of protection as conservation units.