Phylogeny and classification of Naucleeae s.l. (Rubiaceae) inferred from molecular (ITS, rBCL, and tRNT-F) and morphological data.

Parsimony analyses of the tribe Naucleeae sensu lato (s.l.) using the noncoding internal transcribed spacer (ITS) regions of nuclear rDNA, the protein-coding rbcL and noncoding trnT-F regions of chloroplast DNA, and morphological data were performed to construct new intratribal classification, test the monophyly of previous subtribal circumscriptions, and evaluate the generic status of Naucleeae s.l. Fifty-two ITS, 45 rbcL, and 55 trnT-F new sequences are published here. Our study supports the monophyly of the subtribes Anthocephalidae, Mitragynae, Uncariae all sensu Haviland and Naucleinae sensu Ridsdale. There was no support for Cephalanthidae sensu Haviland and Adininae sensu Ridsdale. Naucleeae can be subdivided into six highly supported and morphologically distinct subtribes, Breoniinae, Cephalanthinae, Corynantheinae, Naucleinae, and Mitragyninae, Uncarinae, plus one, Adininae, which is poorly supported. The relationships among these subtribes were largely unresolved. We maintain the following 22 genera: Adina, Adinauclea, Breonadia, Breonia, Burttdavya, Cephalanthus, Gyrostipula, Haldina, Janotia, Ludekia, Metadina, Mitragyna, Myrmeconauclea, Nauclea, Neolamarckia, Neonauclea, Ochreinauclea, Pausinystalia, Pertusadina, Sarcocephalus, Sinoadina, and Uncaria. Pseudocinchona is reestablished. Corynanthe is restricted to C. paniculata and Hallea is reincluded in Mitragyna. Our results were inconclusive for assessing the relationships among Adina, Adinauclea, Metadina, and Pertusadina due to lack of resolution.