Generic delimitations in tuberous Periplocoideae (Apocynaceae) from Africa and Madagascar.
OBJECTIVE
The number of genera included in Apocynaceae subfamily Periplocoideae is a matter of debate. DNA sequences are used here as an independent dataset to clarify generic relationships and classification of the tuberous periplocoid genera and to address the question of the phylogenetic interpretation of pollinia formation in Schlechterella.


METHODS
Representatives of nearly all African and Malagasy genera of Periplocoideae possessing root tubers were analysed using ITS and plastid DNA sequence characters.


RESULTS
Sequence data from non-coding molecular markers (ITS of nrDNA and the trnT-L and trnL-F spacers as well as the trnL intron of plastid DNA) give support for a broad taxonomic concept of Raphionacme including Pentagonanthus. Together with Schlechterella, which is sister to Raphionacme, all Raphionacme-like taxa form a derived monophyletic group of somewhat diverse species. Sister to the Schlechterella/Raphionacme clade is a clade comprising Stomatostemma and the not truly tuberous vine Mondia. In the combined analysis, sister to these two clades combined is a clade formed by Petopentia natalensis and Periploca.


CONCLUSIONS
The recent inclusion of the monotypic South African Petopentia in the monotypic Malagasy endemic Ischnolepis is to be rejected. The Malagasy Camptocarpus is sister to the remainder of Periplocoideae in the ITS and combined analyses, and a Malagasy origin for the subfamily is discussed.
Meve
Ulrich
U
Lehrstuhl für Pflanzensystematik, Universität Bayreuth, 95440 Bayreuth, Germany. ulrich.meve@uni-bayreuth.de
Liede
Sigrid
S
D000349:Africa; D029062:Apocynaceae / Q000145:classification / Q000235:genetics*; D021901:DNA, Intergenic / Q000235:genetics; D018744:DNA, Plant / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000235:genetics; D008270:Madagascar; D008969:Molecular Sequence Data; D031109:Periploca / Q000145:classification / Q000235:genetics; D010802:Phylogeny; D035281:Plant Tubers / Q000235:genetics*; D012343:RNA, Transfer / Q000235:genetics; D017422:Sequence Analysis, DNA
D021901:DNA, Intergenic; D018744:DNA, Plant; D004275:DNA, Ribosomal; D021903:DNA, Ribosomal Spacer; D012343:RNA, Transfer