Systematics Section / ASPT
Jarrell, David C. , Laygo, Miguel R. , Janelsins, Brian M. , Hamed, Hossein H. .
A chloroplast phylogeny of Phalaenopsis (Orchidaceae) based on multiple sequences - an update.
A recent monograph of the Phalaenopsis (tribe Vandeae subtribe Aeridinae) divides the roughly 63 described species into five subgenera with two of these further divided into four sections each. These divisions are based largely on various aspects of the labellum and the column, the highly modified petal and reproductive structure, respectively, of the orchid family. Given that pollinators are directly engaged with these structures, the current monographic treatment may reflect historical patterns of convergent evolution brought about by pollinator selection. Independent data is needed to develop a robust phylogeny and hopefully, a more evolutionarily accurate classification. First, we are currently developing a multilocus chloroplast phylogeny. Analysis of the matK gene and the rps16 intron from a significant sampling of all available species supports a significant taxonomic restructuring. In addition, we are testing other chloroplast regions for phylogenetic utility. At this time, our analysis supports the inclusion of the genera Doritis and Kingidium as synonymous with Phalaenopsis. The large subgenus Polychilos appears monophyletic while its sections are not. The popular subgenus Phalaenopsis is not monophyletic while certain of it sections are monophyletic. Monophyly of other sections and intersectional relationships will be discussed. Placement of taxonomically important morphological characters on this phylogeny is currently limited; however, a progression of labellum callus number from an ancestral state of one to two to three is apparent. Pollinia number, however, appears to change rapidly between two and four throughout the genus. However, those taxa with four pollinia of equal size and those with four pollinia (two large and two small) appear to be separate monophyletic groups. Future directions will be discussed.
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1 - University of Mary Washington, Biological Sciences, 1301 College Av., Jepson Science Center, Fredericksburg, Virginia, 22401, USA
2 - Mary Washington College, Biological Sciences, Jepson Science Center, 1301 College Av., Fredericksburg, Virginia, 22401, USA
Presentation Type: Oral Paper
Location: Salon J - Austin Grand Ballroom/Hilton
Date: Monday, August 15th, 2005
Time: 9:30 AM