|Khan, SA; Razafimandimbison, SG; Bremer, B; Liede-Schumann, S: Sabiceeae and Virectarieae (Rubiaceae, Ixoroideae): One or two tribes? – New tribal and generic circumscriptions of Sabiceeae and biogeography of Sabicea s.l., Taxon, 57(1), 7-23 (2008)|
The results of two recent phylogenetic studies led to the reinstatement of the tribe Sabiceeae, currently classified in the subfamily Ixoroideae s.l. (Rubiaceae) but with conflicting circumscriptions. In the present study, phylogenetic analyses based on nrITS and trnT-F sequence data of 78 taxa are performed to evaluate the different circumscriptions of Sabiceeae, the generic limits within Sabiceeae, and the biogeography of Sabicea. The polyphyly of Sabiceeae sensu Andersson is confirmed, and Pentaloncha and Temnopteryx are shown not to belong to Ixoroideae s.l. but to the subfamily Rubioideae. Our results favour a broad circumscription of Sabiceeae that includes Ecpoma, Hekistocarpa, Pseudosabicea, Sabicea, Schizostigma, Stipularia, Tamridaea and Virectaria. Sabicea sensu Wernham is not monophyletic unless Ecpoma, Pseudosabicea, Schizostigma, and Stipularia are included. We find no support for the monophyly of Stipularia, Sabicea and Pseudosabicea. Therefore, our newly circumscribed Sabiceeae contains only Hekistocarpa, Sabicea s.l. (Ecpoma, Pseudosabicea, Schizostigma, Stipularia), Tamridaea, and Virectaria. Finally, our analyses indicate several dispersal events of Sabicea species between African phytogeographical regions and continental African origins of the Malagasy, São Tomean, Asian, and Neotropical species of Sabicea via perhaps four independent dispersal events.