Abelia and relatives: phylogenetics of Linnaeeae (Dipsacales–Caprifoliaceae s.l.) and a new interpretation of their inflorescence morphology

We present a phylogenetic analysis with sampling from all taxonomic groups in the tribe Linnaeeae (Caprifoliaceae) and interpret the results in relation to inflorescence morphology. Characters from inflorescences are shown to be highly informative for the classification of Linnaeeae; however, they have been neglected in recent studies, possibly as a result of confusion between descriptive and typological views. The phylogenetic relationships of 27 taxa are investigated using the nuclear ribosomal internal transcribed spacer (ITS) region and multiple plastid regions (rbcL, ndhF, matK, trnL intron and trnL-F spacer). Two additional plastid regions, atpB-rbcL and the trnK intron, are also investigated for a subset of taxa. Results indicate that several taxonomic groups, including sections and genera, are not monophyletic. Several groups are supported, e.g. Zabelia, Vesalea and Abelia section Abelia, but Abelia series Serratae is not supported. A new hypothesis for inflorescence evolution in Dipsacales is proposed, and the distinctiveness of Abelia series Serratae is reinforced. The position of tribe Zabeliinae remains unclear within Caprifoliaceae. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, 169, 692–713.