Widespread, common species are of limited value for regional biogeographic studies and of least concern for conservation and land management. In contrast, narrow endemics may be informative for such studies and are usually of high conservation priority. A new species is separated from the widespread species Schoenus melanostachys on the basis of phenetic analysis of morphological data, and integrating evidence from culm anatomy, culm and fruit ornamentation, and corroborated by ecological differentiation. Schoenus rupicola Musili & J.J.Bruhl is found on acid volcanics of south-eastern Queensland and north-eastern New South Wales, adding yet another narrow endemic to the suite of species that characterises the McPherson Range and associated igneous outcrops.