Species richness and distribution of the largest plant radiation of Angola: Euphorbia (Euphorbiaceae)

Knowledge of species richness and distribution of African biodiversity comes primarily from fauna studies, despite the tremendous richness of the flora. The genus Euphorbia (Euphorbiaceae) is one of the most diverse plant genera, and shows a great diversity across Africa. This genus is the largest endemic plant radiation in Angola, including 82 native species with a large diversity of life forms (e.g. herbs, shrubs and trees, and several succulent species) 61% of which are endemics. Considering the great diversity of species, habitats and climatic conditions of Angola, this study aims to: (i) update the inventory of the Euphorbia in this country; (ii) investigate the distribution of these species in the Köppen–Geiger climatic regions, WWF ecoregions, and within the protected areas network; and (iii) use these new findings to devise future conservation programs to protect Angola’s high plant diversity. Our results revealed that there are 49 endemic Euphorbia species (54 endemic taxa) in Angola, most of which occur in the extensive Miombo woodlands, although some species are restricted to the arid zones of southern Angola. The representation of Euphorbia endemics in protected areas was low, with Iona National Park and the Partial Reserve of Namibe showing the best potential for species protection. Centres of diversity and endemism were found in Serra da Chela (Huíla province) and the Angolan Kaokoveld Desert (Namibe province) and must be considered of conservation importance. A re-evaluation of Angola’s protected areas network might be required to facilitate and promote effective conservation of the unique plant diversity of the country.