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Abstract Detail

Systematics/Phytogeography / Taxonomie/ Section

Cortes B., Rocio [1], Motley, Timothy J. [2].

Phylogenetic analysis of the Neotropical tribes Henriquezieae and Posoquerieae (Ixoroideae, Rubiaceae) based on morphology and DNA sequence data from rps16, trnL-F and ITS.

One of four main clades of the subfamily Ixoroideae (Rubiaceae) comprises the tribes Sipaneeae, Henriquezieae and Posoquerieae, which include numerous genera endemic to the phytogeographic region of Guayana. The relationships among this Ixoroideae clade are still very preliminary, because the tribes Henriquezieae and Posoquerieae were poorly sampled in previous studies. A phylogenetic analysis of morphological and DNA sequence data (ITS, rps16 and trnL-F) was performed in order to resolve phylogenetic relationships within the clade, and at the same time to test the monophyly of the genera Gleasonia, Henriquezia and Platycarpum, which are members of the tribe Henriquezieae, and the genera Posoqueria and Molopanthera, which are members of the recently described Posoquerieae tribe. Results indicate that the two tribes and the genera as presently circumscribed are monophyletic. The results also suggest that the Henriquezieae is sister tribe to the Posoquerieae, and they are sister to the tribe Sipaneeae. Synapomorphies of the Posoquerieae tribe are characters related to the “catapult” pollination mechanism, which is unique pollination mechanism in the Rubiaceae. The Henriquezieae is defined by asymmetric corollas with stamens inserted unequally in corolla tube, which is uncommon in the Rubiaceae. The evolution of these pollinator-related traits probably played a crucial role in the diversification of this clade in the very nutrient-poor substrates typical of the Guayana Region.

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1 - Universidad Distrital, Herbario Forestal, Campus El Vivero, Av. Circunvalar, Bogota, Cundinamarca, Colombia
2 - Old Dominion University, Department of Biological Sciences, 110 Mills Godwin Building/45th St, Norfolk, VA, 23529-0266, USA


Presentation Type: Oral Paper:Papers for Sections
Session: 55
Location: 177/Law
Date: Wednesday, July 30th, 2008
Time: 8:00 AM
Number: 55001
Abstract ID:491

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