Systematics Section / ASPT
Pelser, Pieter B. , Nordenstam, Bertil , Kadereit, Joachim W. , Watson, Linda E. .
An ITS phylogeny of Tribe Senecioneae (Asteraceae) and a new delimitation of Senecio.
SENECIONEAE is one of the largest tribes of Asteraceae, comprised of about 150 genera and 3000 species. About 50% of its species are currently assigned to Senecio, making it one of the largest plant genera. Morphological, karyological, and molecular data generated in the past 30 years indicate, however, that this genus and several other genera in the tribe are presumably poly- or paraphyletic. In order to arrive at a generic delimitation of Senecioneae that reflects its evolutionary history, we constructed an ITS phylogeny of the tribe, in which 603 species representing 115 genera are included. These results confirm that several genera, most importantly Senecio, are not monophyletic. We therefore propose a new delimitation of Senecio, which involves transferring the species of Aetheolaena, Culcitium, Hasteola, Iocenes, Lasiocephalus, and Robinsonia to Senecio and the species of Senecio sect. Jacobaea to the genus Jacobaea. Several African succulents should be excluded from Senecio and are better placed in Kleinia or in separate genera. Other Senecio species were nested amongst Dendrophorbium species and should therefore be included in that genus. Furthermore, several clades of Senecio species are sufficiently isolated from Senecio s.s. and distinct from other genera to warrant recognition at the generic level. Although biogeographic analyses could not infer the ancestral area of the tribe and subtribe Tussilagininae unambiguously, subtribe Senecioninae has a clear sub-Saharan African origin. From there, all other continents have been colonized several times independently.
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1 - Miami University, Department of Botany, Oxford, Ohio, 45056, USA
2 - Swedish Museum of Natural History, Department of Phanerogamic Botany, P.O. Box 50007, Stockholm, SE-104 05, Sweden
3 - Johannes Gutenberg-Universität Mainz, Institut für Spezielle Botanik und Botanischer Garten, Bentzelweg 9a, Mainz, D-55099, Germany
Presentation Type: Oral Paper:Papers for Sections
Date: Wednesday, August 2nd, 2006
Time: 1:45 PM