Systematics Section / ASPT
Cortes B., Rocio , Delprete, Piero G. , Motley, Timothy J. .
Systematic studies of the tribe Retiniphylleae (Rubiaceae, Ixoroideae).
The placement of the tribe Retiniphylleae has been unresolved within the Rubiaceae due to the unusual condition of having two collateral ovules per locule. Besides Retiniphyllum, just a few genera have been associated with the tribe: Scyphiphora, an Asiatic genus that includes the only mangrove in the family, and Botryarrhena, a Neotropical genus with two tree species. Retiniphyllum consists of 22 species of shrubs and small trees that grow mostly in white-sand soils of the Guayana and Brazilian Shields, with few species extending into the Amazon Region. The monophyly and the position of the tribe Retiniphylleae in the subfamily Ixoroideae are discussed based on a cladistic analysis of the trnL-F intergenic spacer and the rps16 intron. The phylogenetic relationships within Retiniphyllum are studied based on morphological and ITS sequence data. According to the results, the tribe Retiniphylleae includes only Retiniphyllum, and is sister to two clades that comprise the Ixoroideae sensu Bremekamp. The genus Scyphiphora is sister to a clade that includes the tribes Ixoreae and Vanguerieae. Scyphiphora is neither included in the tribe Gardenieae, nor in the tribe Ixoreae, as previous authors suggested. The genus Botryarrhena is placed within the "Alibertia group", sister to Stachyarrhena, thus unisexual flowers are no longer a synapomorphy supporting the monophyly of the “Alibertia group”. The phylogeny of Retiniphyllum indicates that the hummingbird- and the butterfly-pollination syndromes each arose once while the bee-pollination syndrome arose many times. Additional morphological evolutionary trends indicated by this study will be discussed.
1 - National Herbarium of the Netherlands, Utrecht University Branch, Heidelberglaan 2, 3584 CS, Utrecht, , The Netherlands
2 - Universidad Distrital, Herbario Forestal, Campus El Vivero, Av. Circunvalar, Bogota, Cundinamarca, , Colombia
3 - New York Botanical Garden, Cullman Program for Molecular Systematics Studies, 200th St. & Southern Blvd., Bronx, New York, 10458-5126, USA
Presentation Type: Paper
Location: Cottonwood A (Snowbird Center)
Date: Monday, August 2nd, 2004
Time: 1:45 PM