Populations of a Tasmanian endemic and range-restricted Hibbertia (Dilleniaceae) that are close to but consistently different in morphology from the endangered H. basaltica A.M.Buchanan & Schah. are described as the new species Hibbertia doleritica Schah. While separated geographically by at most c. 20 kilometres, and growing at their closest approach only c. 3 km apart, the two species occur on different substrates and are likely to provide a case study in ecological speciation driven by adaptation to specific soil types. Both species are range-restricted and occur in areas that have been largely cleared of native vegetation.{p}