Origin and early evolution of Ceropegieae (Apocynaceae-Asclepiadoideae)

The first-branching lineages of the tribe Ceropegieae, Anisotominae, Leptadeniinae, and Heterostemminae, are the focus of the present study. In the ingroup we molecularly analysed 34 samples from southern and (north)eastern Africa and Asia for the nuclear internal transcribed spacer (ITS) region, and five plastid markers (trnT-L, trnL-F and trnH-psbA intergenic spacers, trnL, and rps16 introns). Maximum Parsimony and Bayesian analyses were conducted for phylogenetic reconstruction and Bayesian binary MCMC (BBM) analysis as implemented in RASP for testing biogeographic inference. Sister to the well-known hyperdiverse subtribe Stapeliinae (around 700 species) are the Anisotominae, an African subtribe of c. 30 species, with the tropical Neoschumannia in sister-group position to the remaining genera, Anisotoma, Emplectanthus, Riocreuxia, and Sisyranthus. Emplectanthus is sequenced in full for the first time, and its monophyly as sister to Anisotoma is documented. As in Sisyranthus, new sequences in Riocreuxia...