Endemic families of Madagascar. V. A synoptic revision of Eremolaena, Pentachlaena and Perrierodendron (Sarcolaenaceae)

As part of an assessment of the vascular plant families endemic to Madagascar and the Comoro Islands, a synoptic revision is presented of three genera of Sarcolaenaceae: Eremolaena Baill. (2 spp.), Pentachlaena H. Perrier (3 spp.), and Perrierodendron Cavaco (5 spp.). Molecular sequence data place Sarcolaenaceae as the sister group of Dipterocarpaceae within an expanded Malvales. The three genera studied appear to be closely related and probably form a monophyletic assemblage, sharing several diagnostic features (e.g., free stipules and inflorescence bracts, an involucre reduced at anthesis but expanding somewhat in fruit in certain species, and seeds with little or no endosperm and a smooth integument); features separating the genera include sepal size, the number of carpels, and fruit dehiscence. Five species are described as new, including one Pentachlaena (P. betamponensis) and four Perrierodendron (P. capuronii, P. occidentalis, P. quartzitorum and P. rodoense). Keys to the genera and species are provided in English and French.