Annals of the Missouri Botanical Garden vol:96 issue:1 pages:109-132
Third International Rubiaceae Conference edition:3 location:Leuven date:18-21 September 2006
In its current circumscription, the herbaceous tribe Spermacoceae s.l. (Rubiaceae, Rubioideae) unites the former tribes Spermacoceae s. str., Maneltieae, and the Hedyotis-Oldenlandia group. Within Spermacoceae, an(] particularly within the Hedyotis-Oldenlandia group, the generic delimitations tire problematic. Up until now, molecular studies have focused on specific taxonomic problems within the tribe. This study is the first to address phylogenetic relationships within Spermacoceae front a tribal perspective. Sequences of three plastid markers (atpB-rhcL, rps16, and trnL-trnF) were analyzed separately as well as Combined using parsimony and Bayesian approaches. Our results support the expanded tribe Spermacoceae its monophyletic. The former tribe Spermacoceae s. sir. forms it monophyletic clade nested within the Hedyotis-Oldenlandia grcup. Several genera formerly recognized within the Hedyotis-Oldenlandia group are supported as monophyletic (Amphiasma Bremek., Acrytophyllum Willd. ex Schult. & Schult. f., Dentella J. R. Forst. & G. Forst., Kadua Chain. & Schltdl., and Phylohydrax Puff), while others appear to be paraphyletic (e.g., Agathisanthemum Klotzsch), biphyletic (Kohautia Chain. & Schltdl.), or polyphyletic (Hedyotis L. and Oldenlandia L sensu Bremekamp). Morphological investigations of the taxa are ongoing in order to find support for the many new clades and relationships detected. This study provide., a phylogenetic hypothesis with broad sampling across the major lineages of Spermacoceae that can be used to guide future species-level and generic studies.