Research into the systematics of Prostanthera recently revealed close evolutionary relationship among P. phylicifolia sens. str., the critically endangered P. gilesii, and a population of uncertain identity from the Central Tablelands of New South Wales (NSW), Australia. Previous analyses were unable to establish whether genetic boundaries separated these taxa. This study assessed species boundaries among these three taxa by using a combination of single-nucleotide polymorphisms (SNPs) sampled at the population-scale and multivariate analysis of morphological characters. Ordination, model-based clustering, F-statistics, neighbour-network analysis, phylogenetic analysis, and ancestry coefficient estimates all provided support for discrete genetic differences among the three taxa. Morphological phenetic analysis recovered congruent morphological clusters and identified a suite of corresponding diagnostic characters. This congruence of molecular and morphological evidence supports the presence of three independently evolving lineages, two of which correspond with the previously described P. gilesii and P. phylicifolia sens. str. The third taxon, represented by a single population from the Central Tablelands of NSW, is here described as P. volucris R.P.O’Donnell. A detailed description, diagnostic line drawings and photographs are provided. We evaluate P. volucris as satisfying criteria to be considered Critically Endangered.