PHYLOGENY OF RUBIACEAE-RUBIEAE INFERRED FROM THE SEQUENCE OF A CPDNA INTERGENE REGION

A phylogenetic analysis of 25 species, representing eight genera of th e Rubieae tribe (Rubiaceae), has been made using the DNA sequence of t he chloroplast atp B-rbc L intergene region. Six tropical genera from other tribes of Rubiaceae have been used as outgroups. Whatever the me thod of analysis (distance, parsimony or maximum likelihood), five gro ups are clearly separated and described as informal clades. Their rela tive relationships are not clearly resolved by the parsimony analysis, resulting in eight equally parsimonious trees, 327 steps long, with a consistency index (CI) of 0.749 (excluding uninformative sites). The Rubieae tribe appears monophyletic from the data available. Some new a nd partly unexpected phylogenetic relationships are suggested. The gen us Rubia forms a separate clade and appears to be the relatively advan ced sister group of the remaining taxa. The Sherardia clade also inclu des the genera Crucianella and Phuopsis. Galium sect. Aparinoides appe ars closely attached to the Asperula sect. Glabella clade. The remaini ng taxa of Galium are paraphyletic: Galium sect. Platygalium (in the C ruciata clade) is linked to the advanced genera Cruciata and Valantia; the more apomorphic groups of Galium form the Galium sect. Galium cla de, including the perennial sections Galium, Leiogalium, and Leptogali um as well as the annual (and possibly polyphyletic) sect. Kolgyda.