A synopsis of Pseudovigna (Leguminosae: Papilionoideae) including a new species, P. sulaensis, from Sierra Leone Ruth Clark 1 , Xander van der Burgt 1 , Hannah Banks 2 , Abdulai M. B. Feika 3 & Gwilym Lewis 1 Summary. Pseudovigna sulaensis R. Clark & Burgt (Leguminosae: Papilionoideae), a new species from Sierra Leone, is described and illustrated. It is a herb from submontane grassland, with annual twining stems to several metres long, sprouting from a perennial woody rootstock. The erect inflorescences have violet flowers. The new species is only known from the Sula Mountains in northern Sierra Leone; it was found there at 10 localities, of which nine are on summits of hills. The pollen of the new species is analysed. Descriptions, illustrations and distribution maps of the other two species in the genus Pseudovigna, P. argentea (Willd.) Verdc. and P. puerarioides Ern are provided. A key to the three species of Pseudovigna is given. Notes on generic characterisation, partly through molecular analysis, are also provided. The IUCN conservation status of P. sulaensis is assessed as Vulnerable; of the other two species as Least Concern. Key Words. Fabaceae, Faboideae, Pseudovigna argentea, Pseudovigna puerarioides, taxonomy. Introduction During the first field trip of a series of vegetation surveys in the southern Sula Mountains in northern Sierra Leone, a plant from the legume subfamily Papilionoideae was found growing abundantly in grassland on the 800 m high summit of a hill. The plant was collected in flower and in fruit. After a search of phaseoloid genera known to occur in the tropics, it was concluded that the plant represents a new species in the genus Pseudovigna. The new species was thoroughly studied during four more field trips to the Sula Mountains. Pseudovigna is a small genus of three species of trailing or climbing perennial herbs, occurring in Africa. The genus was first described by Harms in 1915 as Dolichos sect. Pseudovigna. The section was raised to generic rank by Verdcourt (1970), who made the new combination Pseudovigna argentea (Willd.) Verdc. based on Dolichos argenteus Willd. (1802). A second species, P. puerarioides, was described by Ern (1980). Pseudovigna is placed in tribe Phaseoleae, subtribe Glycininae, based on molecular data (Schrire, in Lewis et al. 2005). Pseudovigna appears to be closely allied to the genus Sinodolichos, a genus of two species, known from China, Myanmar, Thailand, and Borneo (Sarawak). Despite the different geographical ranges, Pseudovigna and Sinodolichos are morphologically rather similar, both having the same trichomes on the fruit and other parts, the reticulate seed testa, a penicillate stigma, and fusion of the two upper calyx lobes. Sinodolichos differs from Pseudovigna in the shape of the stigma, which is capitate in Pseudovigna, and funnel-shaped in Sinodolichos; the style, which is flattened in the lower half in Pseudovigna, and uniformly cylindrical in Sinodolichos; and the structure of the pollen: in Sinodolichos the pollen is compressed, triporate, triangular in equatorial section (Verdcourt 1970), whereas the pollen grains of Pseudovigna are isopolar, spheroidal to oblate in shape, tricolporate, with psilate aperture membranes. Analysis of the pollen of this new species supports its inclusion in the genus Pseudovigna. A molecular analysis of the new species supports the conclusions reached by study of the morphology. A parsimony phylogenetic analysis based on nucleo- tide sequences from the matK plastid region, which included the new taxon and several members of subtribe Glycineae (sensu Schrire in Lewis et al. 2005), recovered a strongly supported (100% boot- strap) Pseudovigna clade in which P. sulaensis was placed (also with 100% bootstrap support) as sister to two accessions of P. argentea (Lavin et al., unpub- lished data). The analysis also provided evidence for separating P. sulaensis as a distinct species: a compar- ison of the three Pseudovigna accessions in the aligned Accepted for publication December 2011. 1 Herbarium, Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AB, UK. e-mail: r.clark@kew.org 2 Jodrell Laboratory, Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AB, UK. 3 National Herbarium of Sierra Leone, Njala University, Njala, Sierra Leone. KEW BULLETIN VOL. 66: 589Y599 (2011) © The Board of Trustees of the Royal Botanic Gardens, Kew, 2012