A new species in the previously monotypic, endemic New Caledonian genus Gastrolepis (Stemonuraceae) is described. Gastrolepis alticoladiffers from G. austrocaledonica by its shorter and thicker petioles, strongly coriaceous leaves with revolute margins, shorter inflorescences, and pubescent corollas. The new species is further distinguished by its ecology, occurring only in high-altitude maquis on two massifs in southern New Caledonia, Mt. Kouakoué and the Montagne des Sources. Gastrolepis alticola is assigned a preliminary conservation status of ‘Endangered’ using the World Conservation Union (IUCN) Red List criteria. Comparison of the IUCN threat status for the 19 species endemic to this distinctive, restricted vegetation type reveals a striking lack of consistency and underscores the need for a reassessment of the entire New Caledonian flora. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 157, 775–783.