Molecular phylogeny of the southern African endemic genus Sisyranthus (Apocynaceae: Asclepiadoideae-Ceropegieae)

Abstract

Sisyranthus E.Mey. species are placed in the tribe Ceropegieae, subtribe Anisotominae (Apocynaceae-Asclepiadoideae). Plants have their fertile parts hidden in the tube of the flowers, and are cryptic in both their habit and small flower size making it difficult to find them in the wild. The genus was first described by Meyer in 1837 and last revised in Flora Capensis (1908) with only one new species described since then. Currently the genus comprises 13 recognised species found in the grasslands of southern Africa, with one species restricted to Zimbabwe. Many of the species are range-restricted and poorly known. The existing key is difficult to use thus leading to confusing identifications. In existing DNA phylogenies, the subtribe Anisotominae has been under sampled and a broader sampling of the southern African taxa is required in order to resolve relationships within and between Sisyranthus and its close allies. A revision will lead to a better understanding of the group and its affinities. The aims of this study was: (1) to produce a molecular phylogeny for Sisyranthus and its close relatives using sequence data from two nuclear markers (ITS and ETS) and five plastid regions (matK, ndhF, rbcLa, trnL-F, and ycf1); (2) to map morphological characters onto the resulting phylogeny; (3) to revise the genus; and to (4) produce a key to properly identify the species. Preliminary results will be discussed