Expanding our knowledge of the coffee family in continental Africa: a synopsis of the genus Pyrostria (Rubiaceae)

A summary of the species of Pyrostria from continental Africa is presented, including full descriptions of three new species, P. makovui, P. namacubiensis and P. rovumensis from the coastal forests of the Tanzania-Mozambique border region, and one new subspecies, P. lobulata subsp. bridsoniae from Zambia. Pyrostria makovui is the first species with plurilocular (3-lobed) fruits and the second hermaphrodite species for the study area, characters that are otherwise found mainly in taxa of Pyrostria from Madagascar and surrounding islands. Five of the 16 species treated in this synopsis remain undescribed because they are known only from incomplete material. A key to the species of Pyrostria occurring in continental Africa is presented and notes on the distribution, habitat and relevant taxonomic considerations are provided, along with an assessment of the conservation status (extinction risk) for each species. The Coastal Forests of Eastern Africa Biodiversity Hotspot is found to be a centre of diversity for Pyrostria, with the Rovuma Centre of Plant Endemism in Mozambique and Tanzania being particularly rich in endemic species.