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Systematics Section / ASPT

Singer, Rodrigo [2], Koehler, Samantha [2], Williams, N. H. [1], Whitten, W. M. [1], do Amaral, Maria do Carmo [2].

Phylogenetic studies in brazilian Maxillariinae orchids.

Strong molecular and non-molecular evidence supports the subtribe Maxillariinae s.l. as a monophyletic assemblage of species. However, generic boundaries within this taxonomically challenging group are unsatisfactory. To attempt a molecular and morphological phylogenetic revision of this subtribe, a collaboration among researchers of different countries has been established. The goals of our project are to (1) gather sequence data from nrDNA ITS, trnL-F and matK chloroplast DNA regions of representative Brazilian Maxillariinae orchids in order to estimate the phylogenetic position of Brazilian species and groups of species, clarifying their relationships within this subtribe; (2) obtain sets of ecological and morphological characters (flower and vegetative morphology, chemistry of flower rewards, breeding systems, pollination biology) that may help to identify and support clades; (3) revise the generic and subgeneric classification of problematic groups to facilitate further taxonomic revisions. Preliminary results based on ITS sequence data and morphological studies support two monophyletic groups occurring mainly in South-Southeastern Brazil (the Maxillaria picta and M. madida alliances) that can be easily recognized by several vegetative and floral features, including lack of rewards. Another monophyletic assemblage includes the rewarding species of the M. discolor and M. valenzuelana alliances which comprise both unifoliate, pseudobulbous plants or pseudobulbless species. Interestingly, flower features, and features such as bifoliate pseudobulbs separated by long rhizomes covered by bracts, pollinarium morphology, and similar lip secretions, are quite constant within the reward-offering species M. cerifera, M. notylioglossa and M. friedrichstahlii. However, additional phylogenetic studies are necessary to corroborate if these species constitute a monophyletic group.


1 - University of Florida, Department of Natural History, Florida Museum of Natural History, P.O. Box 117800, Gainesville, Florida, 32611-7800, USA
2 - Universidade Estadual de Campinas, Departamento de Botanica, Caixa Postal 6109, Campinas, Sao Paulo, 13083 970, Brazil

Keywords:
Maxillaria
Orchidaceae
nrDNA ITS
matK
trnL-F
pollination biology.

Presentation Type: Poster
Session: 32-78
Location: Special Event Center (Cliff Lodge)
Date: Tuesday, August 3rd, 2004
Time: 12:30 PM
Abstract ID:497


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