Systematics Section / ASPT
Redden, Karen , Herendeen, Patrick S. , Bruneau, Anne .
Morphology and phylogeny of Elizabetha, Heterostemon, Paloue, and Paloveopsis (Leguminosae, Caesalpinioideae) from northeastern South America.
Most phylogenetic work within the subfamily Caesalpinioideae concentrates on higher level relationships among the tribes, subtribes, and genus groups. Over half of the genera of Caesalpinioideae are grouped in the large Detarieae s.l. clade. Within this group, Heterostemon (7 spp.), Elizabetha (10 spp.), Paloue (4 spp.) and Paloveopsis (1 sp.) are members of the Brownea clade that are endemic to northeastern South America. Conflicting patterns of character distributions among these genera have presented difficulties for generic delimitation. These conflicts were recognized by Richard Cowan in his 1954 description of the monotypic genus Paloveopsis, which combines certain features of Paloue and Elizabetha. He also suggested the possibility that these genera may need to be reorganized, rearranged or merged. This study uses combined morphological and molecular data to explore generic limits and relationships among these genera. The data set includes 165 morphological and anatomical characters from vegetative and reproductive structures for all species and DNA sequence data from multiple genes for most species. Patterns of morphological evolution in flower structure and leaf form will be examined based on the inferred phylogeny. Prelimimary data based on trnL intron sequences suggest that Paloue and Elizabetha may not be monophyletic. The occurrence of simple leaves is shared by Paloue and Paloveopsis, but simplification of leaf structure has also occurred in some species of Heterostemon and Elizabetha. Likewise, loss or reduction of some petals and stamens appears to have occurred multiple times in this group.
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1 - The George Washington University, Department of Biological Sciences, Lisner Hall 340, 2023 G Street, NW, Washington, DC, 20052, USA
2 - George Washington University, Biological Sciences, 2023 G St.NW, Washington, DC, 20052, USA
3 - Université de Montréal, Institut de recherche en biologie végétale, 4101 rue Sherbrooke est, Montréal, Québec, H1X 2B2, Canada
Presentation Type: Oral Paper
Location: Salon G - Austin Grand Ballroom/Hilton
Date: Wednesday, August 17th, 2005
Time: 9:30 AM