Rhynchosia bolusii (Phaseoleae, Fabaceae), a new species from the Western Cape Province of South Africa

The pantropical genus Rhynchosia Lour. (1790: 425) comprises some 230 species (Schrire 2005), of which about 58 occur in South Africa (Germishuizen 2006). Rhynchosia is closely related to Eriosema (DC. 1825: 388) Rchb. (1828: 150) and is placed within the subtribe Cajaninae of the tribe Phaseoleae (Schrire 2005). The South African species were last studied by Baker (1923) who recognized 59 species, arranged into 5 sections, although several species have been synonymised in the recent checklist of South African plants (Germishuizen 2006). Several new species have also been described since Baker's revision (e. g. Stirton 1981; Germishuizen 1998, 2011) and the genus is currently the subject of ongoing taxonomic studies (Moteetee et al. 2012; Moteetee et al. submitted). While studying the collections of Rhynchosia at the Compton Herbarium, Cape Town, an as yet unnamed species of the section Rhynchosia (section Eurhynchosia sensu Baker 1923) was discovered among the indeterminatae and is described herein.