|Meve, U; Liede-Schumann, S: Ceropegia (Apocynaceae, Asclepiadoideae, Ceropegiinae): paraphyletic, but still taxonomically sound, Annals of the Missouri Botanical Garden, 94, 392-406 (2007)|
|Key words: Brachystelma, Ceropegia, ITS, molecular systematics, morphology, paraphyly, phylogeny, trnL intron, trnT-L and trnL-F spacers|
Even though the species-rich genus Ceropegia L. (Apocynaceae, Ceropegieae) is convincingly characterized by its pitfall flowers, investigation of non-coding markers of chloroplast DNA (cpDNA) (trnT-L and trnL-F spacers and the trnL intron) and nuclear ribosomal DNA (nrDNA) (ITS) has shown that Ceropegia is twice paraphyletic. The 36 analyzed Ceropegia taxa scatter over a grade of seven clades. One clade is shared by Ceropegia and all Brachystelma R. Br. species investigated, making Ceropegia (without Brachystelma) paraphyletic. All endemic Madagascan Ceropegia taxa investigated and the East African C. robynsiana Werderm. share a terminal, but not further-resolved clade with the stapeliads. Thus, again, Ceropegia without the stapeliads is paraphyletic. These results are incongruent with current taxonomy. In the absence of adequate morphological, anatomical, or karyological characters supporting a taxonomic reclassification of the genus in accordance with the retrieved clades of the phylogenetic analysis, it is proposed that the current taxonomy be maintained.