Systematics Section / ASPT
Nicolas, Antoine N. , Plunkett, Gregory M. .
Placement of the Hydrocotyloids Based on a New Phylogeny with Expanded Sampling across the Order Apiales.
Subfamily Hydrocotyloideae sensu Drude represents an unnatural grouping of 41 genera in Apiaceae, but the correct division of this subfamily among the major clades of the order Apiales has not yet been achieved. We have sampled nearly 90% of hydrocotyloid genera and assembled a dataset based on plastid sequences from the trnD-trnT region. Taxon sampling also includes representation from all major clades and subclades of Apiales (Apiaceae subfamilies Apioideae and Saniculoideae, nearly all genera of Araliaceae, and all genera of Pittosporaceae, Myodocarpaceae, Grisiliniaceae, Torricelliaceae, and Pennantiaceae). The polyphyly of Hydrocotyloideae was confirmed with the recognition of at least 8 major clades. One clade unites the cosmopolitan Hydrocotyle with the Australasian Trachymene and Uldinia as sister to Araliaceae s. str. The largely southern African Centella, the tropical American Micropleura, and several Australian genera constitute a clade together with two former araliads (Mackinlaya and Apiopetalum) in Apiaceae subfamily Mackinlayoideae. The six remaining clades are placed within core Apiaceae. Three monogeneric clades (viz., the Australian Platysace, the Brazilian Klotzschia, and the South African Hermas) represent three different Gondwanan elements at the base of Apiaceae. Three other clades have recently been described as subfamily Azorelloideae, but this subfamily may not be monophyletic. The three clades include the Astericium clade (five genera from the New World), the Bowlesia clade (three genera from the New World, one from the Canary Is., and one from Australia) and the Azorella clade (five genera from the New World, one from E Asia, four from Australia). At a generic level, Azorella appears paraphyletic and has two major subclades: one unites some species of Azorella with Mulinum and Laretia; the second unites the other species of Azorella with Schizeilema, Huanaca and Stilbocarpa. These results are being tested against data from the plastid rpl16 and the mitochondrial nad1 intron 2 region.
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1 - Virginia Commonwealth University, Department of Biology, P.O. Box 842012, Richmond, Virginia, 23284
2 - Virginia Commonwealth University, Department of Biology, P.O. Box 842012, Richmond, Virginia, 23284, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Lake Erie/Hilton
Date: Monday, July 9th, 2007
Time: 1:15 PM