Bolin, Jay F. , Motley, Timothy J. , Wurdack, Kenneth , Maass, Erika , Musselman, Lytton John .
A molecular phylogeny and revised taxonomy of the holoparasitic family Hydnoraceae.
Using nuclear (ITS) and plastid (rpoB) DNA sequences, we present the first phylogeny of the holoparasitic family Hydnoraceae (Piperales). The family contains two genera, Hydnora and Prosopanche, that were resolved as sister clades in rooted (with Piper nigrum) maximum parsimony and Bayesian analyses. The species are parasites on two rosid plant lineages. The ancestral host association seems to be on members of the Fabaceae followed by a single host-shift to Euphorbia spp. (Euphorbiaceae) in Hydnora. Morphological evolution of Hydnora revealed that rhizome shape is a homoplastic character, thus a poor character for defining intrageneric sections. In contrast, synapomorphies included osmophore position and tepal color. Within Hydnora africana s.l., “cryptic species” were discovered including a new species from southern Namibia and the recognition of Hydnora longicollis Welw. in Angola and northern Namibia. We have shown that the “cryptic species” can be distinguished by floral odor and floral metrics. Within the Euphorbia-parasitizing clade of Hydnora in southern Africa an apparent radiation of species is based on allopatry, extreme climatic variation, and potentially host based co-speciation. Significant work may be needed to revise the taxonomy of the Fabaceae-parasitizing clade of African Hydnora (excluding Hydnora esculenta), where only two species are currently recognized, but where at least six formerly recognized species from east and northern Africa remain unevaluated. In Prosopanche, the earliest diverging lineage is Prosopanche bonacinae and additional data maybe required to resolve the apparent sister taxa, Prosopanche americana and Prosopanche costaricensis.
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1 - Smithsonian Institution, Department of Botany, MRC-166, National Museum of Natural History, PO Box 37012, Washington, DC, 20013-7012, USA
2 - Old Dominion University, Department of Biological Sciences, 110 Mills Godwin Building/45th St, Norfolk, VA, 23529-0266, USA
3 - University of Namibia, Department of Biology, Private Bag 13301, Windhoek, Namibia
Presentation Type: Oral Paper:Papers for Sections
Location: 552A/Convention Center
Date: Tuesday, August 3rd, 2010
Time: 8:30 AM