Evolution and trends in the Psychotrieae alliance (Rubiaceae)—A rarely reported evolutionary change of many-seeded carpels from one-seeded carpels Sylvain G. Razafimandimbison * , Catarina Rydin, Birgitta Bremer Bergius Foundation, Royal Swedish Academy of Sciences and Botany Department, Stockholm University, SE-10691 Stockholm, Sweden article info Article history: Received 7 November 2007 Revised 26 March 2008 Accepted 29 March 2008 Available online 7 April 2008 Keywords: atpB-rbcL spacer Classification Mitchelleae Morindeae s.s. ndhF nrITS Psychotrieae alliance rbcL rps16 Rubioideae Rubiaceae trnT-F abstract Bayesian and parsimony analyses of five plastid gene and nrITS regions from 58 Rubioideae (Rubiaceae) taxa further support the sister-group relationship between the African monotypic genus Schizocolea and the Psychotrieae alliance sensu Bremer & Manen. Our analyses show that the Psychotrieae alliance can be subdivided into in four well-supported clades: Schizocolea, (Schradereae(Gaertnereae(Mitchelleae–Mor- indeae s.s.))), Palicoureeae–Psychotrieae s.s., and Craterispermeae–Prismatomerideae. The relationships between the latter three clades remain unsettled. Our study further reveals much higher numbers of molecular autapomorphies of the tribes compared with those of molecular synapomorphies of two sister tribes or groups of tribes. Within the newly delimited Psychotrieae alliance a one-seeded carpel was inferred as ancestral and many- and two-seeded carpels evolved once each. We describe Mitchelleae to accommodate Damnacanthus and Mitchella and restrict Morindeae to include only Appunia, Coelosper- mum, Gynochthodes, Morinda, Pogonolobus, and Syphonandrium. Mitchelleae is characterized e.g., by pla- centae inserted near the top of the septum and a single campylotropous ovule per carpel, while Morindeae s.s. has massive and T-shaped placentae inserted in the middle of the septum and two anat- ropous ovules per carpel. Ó 2008 Elsevier Inc. All rights reserved. 1. Introduction Rubioideae Verdc. (Verdcourt, 1958), the largest subfamily in the coffee family (Rubiaceae) with ca. 7475 species (Govaerts et al., 2006), is a well-defined monophyletic group that can easily be diagnosed by the presence of raphide idioblasts, valvate corolla aestivation and often heterostylous flowers. Our knowledge of the subfamily has recently been improved as a result of a series of independent molecular phylogenetic studies of Rubiaceae (Bremer, 1996a; Andersson and Rova, 1999; Bremer and Manen, 2000; Rob- brecht and Manen, 2006). For examples, the sister-group relation- ship between the African monotypic genus Colletoecema Petit (1963) and the remaining Rubioideae was shown for the first time by Robbrecht and Manen (2006). The tribes Lasiantheae Bremer and Manen (2000) and Coussareeae Hooker (1873) were demon- strated to be successive sister groups to the large Psychotrieae and Spermacoceae alliances (both sensu Bremer and Manen, 2000), which are in turn sisters (e.g., Andersson and Rova, 1999; Bremer and Manen, 2000). Despite the largely congruent results from these independent studies, there were some noticeable discrepancies such as, the phylogenetic positions of the tribes Urophylleae Bremek. ex Verdc. and Ophiorrhizeae Bremek. ex Verdc. (Verdcourt, 1958) and the tribal delimitations and relation- ships within the Psychotrieae alliance (see Fig. 1A–D). This latter group is the main focus of the present study. The Psychotrieae alliance sensu Bremer and Manen (2000) [also known as Psychotrieae s.l., Bremer (1996a); the Gaertnereae-Mor- indeae–Psychotrieae complex, Andersson and Rova (1999); super- tribe Psychotriidinae, Robbrecht and Manen (2006)] is mostly tropical, with the exception of the East Asian Damnacanthus C.F.Gaertn. and the North American and East Asian Mitchella L., which are restricted to the temperate regions. The alliance is char- acterized by its fleshy (drupes or berries) fruits, which are consid- ered important food sources for many tropical frugivorous birds (Snow, 1981). It is a predominantly woody group consisting of ca. 3000 species (ca. 1/4 of Rubiaceae) (Govaerts et al., 2006) belonging to ca. 54 genera, which have previously been classified in four to six tribes (see Table 1). These tribes are morphologically distinct and apparently share no obvious morphological synapo- morphies. As a result, the tribal relationships within the Psychot- rieae alliance have always been unsettled (see Fig. 1A–D) and are the major issues in the recent discussions about the classification 1055-7903/$ - see front matter Ó 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.ympev.2008.03.034 * Corresponding author. Fax: +46 (0) 8 16 55 25. E-mail address: sylvain.razafimandimbison@bergianska.se (S.G. Razafimandim- bison). Molecular Phylogenetics and Evolution 48 (2008) 207–223 Contents lists available at ScienceDirect Molecular Phylogenetics and Evolution journal homepage: www.elsevier.com/locate/ympev