Systematics/Phytogeography / Taxonomie/ Section
Cordes, Jenny M. , Downie, Stephen R. .
Molecular systematic evidence supporting distinction of a rare Greek endemic and its southern African relatives: the genus Conium (Apiaceae) redefined.
Conium L., or poison hemlock, is viewed by recent authors either as a monotypic genus or as encompassing up to four additional species, a situation which creates substantial conflict in the literature. The most common species, C. maculatum, is a native of Europe, western Asia and northern Africa, and has naturalized as a weed in the Americas, Australia, and New Zealand. C. divaricatum is a Greek mountain endemic which has been variously treated as either its own species or a variety of C. maculatum. Three species of Conium are endemic to southern Africa (C. chaerophylloides, C. fontanum, and C. sphaerocarpum), but these too have been proposed to be mere forms of the highly variable C. maculatum. The most recent treatment of the genus also suggests that a variant of C. maculatum in Arabia and Ethiopia with unspotted stems may represent an additional unique species of Conium, but this variant has yet to be formally described. In order to address the uncertain taxonomic rankings of each of these taxa, we are sequencing the nrDNA ITS and ETS markers along with several loci from the chloroplast genome. Preliminary data have revealed C. divaricatum as sister to the remaining species of Conium. This finding is supported by distinctive morphological characters, most notably in the taxon’s unspotted but reddish-colored stem and its tendency toward broader, more coarsely decompound leaves. Analyses using ITS data alone demonstrate that the southern African species constitute a monophyletic group with a close relationship to C. maculatum, but these data fail to ascertain the monophyly of each species within the clade. The addition of ETS and cpDNA data to this study will verify monophyly and offer credence for appropriate taxonomic ranks for each taxon, and will establish phylogenetic relationships within the genus.
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1 - University of Illinois Urbana, Department of Plant Biology, 265 Morrill Hall, 505 South Goodwin Avenue, Urbana, Illinois, 61801-3707, USA
Presentation Type: Poster:Posters for Sections
Location: Ball Room & Party Room/SUB
Date: Monday, July 28th, 2008
Time: 12:30 PM