A taxonomic revision of Bonatea Willd. (Orchidaceae: Orchidoideae: Habenariinae)

The diagnostic characters for Bonatea Willd. (Orchidaceae) are re-evaluated. The genus is distinguished from Habenaria by the possession of a galeate rostellum, which is clearly separated from the vertical anthers, and a tooth in the spur mouth (secondarily lost in Bonatea rabaiensis (Rendle) Rolfe). Morphological evidence suggests that Bonatea bracteata G.McDonald and McMurtry and Bonatea tentaculifera Summerh. are better placed in Habenaria, where B. bracteata is treated as a synonym of Habenaria transvaalensis Schltr., and B. tentaculifera is renamed Habenaria bonateoides M.Ponsie. A taxonomic revision and key to the species of Bonatea is presented. Fourteen species are recognized, ten of which are found in South Africa. Full descriptions are provided with diagnostic characters and distribution maps. Bonatea eminii (Kraenzl.) Rolfe, known from a single collection destroyed in Berlin, is closely allied to Bonatea steudneri (Rchb.f.) T.Durand and Schinz but is excluded from the revision due to insufficient information.