The new species Aristea farafangana Goldblatt & Phillipson, sp. nov. (Iridaceae) from Madagascar, biogeographic notes on Aristea Aiton in Madagascar and a revised key to the genus

The new species, Aristea farafangana Goldblatt & Phillipson, sp. nov., known from a single collection from southeastern Madagascar, has soft textured leaves, a flattened, few-branched stem, and inflorescences (binate rhipidia) consisting of up to ten flowers, borne on pedicels c. 4 mm long. The inflorescence spathes and floral bracts are distinctive in being short, narrow at the base and attenuate. The species may be most closely related to A. cladocarpa Baker, which has up to four flowers per binate rhipidium and larger floral bracts that conceal the 3-4 mm long pedicels. A morphology-based phylogeny suggests that Aristea in Madagascar may have colonized the Island from Africa at least four times, resulting in the presence there of eight species, seven of them endemic.