SUBFAMILIAL AND TRIBAL RELATIONSHIPS IN THE RUBIACEAE BASED ON RBCL SEQUENCE DATA

A parsimony analysis of rbcL sequences from 49 Rubiaceae genera (representing 23 tribes) and 7 outgroup taxa was performed. Species representing 48 genera of Rubiaceae were sequenced: Anthospermum, Antirhea, Bertiera, Bouvardia, Calycophyllum, Catesbaea, Cephalanthus, Cinchona, Coffea, Cubanola, Deppea, Enterospermum, Erithalis, Exostema, Gardenia, Guettarda, Haldina, Hallea, Hamelia, Hillia, Hintonia, Hoffmannia, Hydnophytum, Ixora, Keetia, Luculia, Meyna, Mitriostigma, Morinda, Mussaenda, Nauclea, Nertera, Oldenlandia, Ophiorrhiza, Parapentas, Pentagonia, Pentas, Pentodon, Pinckneya, Pogonopus, Psychotria, Rachicallis, Rogiera, Rubia, Sarcocephalus, Theligonum, Uncaria, and Vangueria. The cladistic analysis resulted in 24 equally parsimonious trees with a consistency index (C.I.) of 0.38. The results were analyzed to test higher-level classification and reconstruction of Rubiaceae phylogeny, and to place taxa with disputed taxonomic positions. There are three groups of taxa more or less corresponding to three of Robbrecht's four subfamilies: Cinchonoideae s. str., Ixoroideae s.l., and Rubioideae. There is no support for the subfamily Antirheoideae, the taxa of which are nested within Cinchonoideae s. str, and Ixoroideae s.l. The positions of Luculia and Hintonia are uncertain. The tribal positions (sensu Robbrecht) are supported for a majority of the genera, but other indicated relationships contradict earlier classification. The data, although based on a limited number of taxa, support the monophyly of the tribes Anthospermeae, Chiococceae s.l., Guettardeae, Hamelieae, Hedyotideae, Naucleeae s.l., Psychotrieae, and Vanguerieae, but there is no support for the positions and/or narrow circumscriptions of Cephalantheae and subtribe Mitragyninae (Cinchoneae), or for a wide circumscription of Cinchoneae. The rbcL data also give useful suggestions for taxonomic positions of the following genera with uncertain affiliations: Bertiera, Catesbaea, Deppea, Hillia, Ophiorrhiza, Rachicallis, and Theligonum.