Systematics/Phytogeography / Taxonomie/ Section
Wright, Michael , Stefanovic, Sasa , Costea, Mihai .
Cuscuta salina (Salt marsh dodder; Convolvulaceae): one species or two?
Cuscuta salina refers to an assemblage of inbreeding forms that parasitize hosts growing in alkaline/saline habitats from western North America. Three varieties have been historically described to encompass the morphologic variation displayed by these parasitic plants: var. salina, var. major, and var. papillata. A morphometric study of flower characters, SEM, and DNA sequence data from plastid and nuclear regions were used to analyze the patterns of variation, define lineages/taxa and investigate their phylogenetic relationships. Principal components, canonical, and clustering analyses, as well as the molecular results indicate that only two lineages/taxa can be distinguished. These lineages are sister taxa and correspond largely to var. salina and var. major. Cuscuta salina var. papillata, in the strict sense defined by Yuncker, clusters with var. major, from which it differs through the presence of papillae on the calyx. The two main lineages, 'salina' and 'major', share a small area of sympatry in southern and Lower California, but otherwise have a distinct biogeography and host specificity. ‘Salina’ occurs mostly in inland vernal pools and salt flats from California, Nevada, Arizona and Mexico and grows primarily on Frankenia and Suaeda. ‘Major’ can be found in coastal salt marshes from British Columbia to Baja California, on Salicornia and Jaumea carnosa. Morphologically ‘salina’ has smaller flowers, 2.5–4 (4.5) mm long and cylindric to narrow campanulate corollas with ovate-lanceolate lobes, while in ‘major’ flowers are 3.75–5(5.5) mm long and corollas campanulate with broadly ovate lobes. Infrastaminal scales are shorter and with less fimbria in ‘major’, compared to ‘salina’. Taking into account their reproductive isolation, morphological, biogeographic and host distinctiveness, the two lineages can alternatively be treated at specific rank, in which case the description of a new species for the latter is required.
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Digital Atlas of Cuscuta
1 - Wilfrid Laurier University, Biology, 75 University Avenue W, Waterloo, Ontario, N2L 3C5, Canada
2 - University of Toronto at Mississauga, Biology, 3359 Mississauga Rd N, Mississauga, Ontario, L5L1C6, Canada
3 - Wilfrid Laurier University, Biology, 75 University Ave N, Waterloo, Ontario, N2L3C5, Canada
Presentation Type: Poster:Posters for Sections
Location: Ball Room & Party Room/SUB
Date: Monday, July 28th, 2008
Time: 12:30 PM