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Abstract Detail

Systematics Section

Treher, Amanda C. [1], Naczi, Robert F C [2].

Resolving the taxonomically controversial Rhynchospora filifolia species complex (section Fuscae, Cyperaceae).

With 250300 species, Rhynchospora is one of the largest genera of Cyperaceae. Rhynchospora is cosmopolitan, but most diverse in the Neotropics. Section Fuscae is especially important because it contains narrow endemics, species of conservation concern, and both tropical and temperate species. It is unknown if section Fuscae is monophyletic. The R. filifolia complex contains several species with controversial synonymy and taxonomic ranks, and considerable identification challenges. Two members of the complex, R. harperi and R. filifolia, have extensive, overlapping geographic ranges from South America to Delaware and Central America to New Jersey, respectively. Some authors suggest that these species are indistinct. Morphological plasticity of R. filifolia may explain the challenges in distinguishing it from other species of the complex, like R. fuscoides, a Cuban endemic considered synonymous with R. filifolia by some authors. We will test three hypotheses that address the number of species in the complex and their taxonomic ranks: (1) R. harperi is distinct from R. filifolia; (2) the morphological variation within R. filifolia is due to a geographic cline; and (3) R. fuscoides is a distinct species and not synonymous with R. filifolia. We measured fifteen macromorphological characters on over 100 specimens from throughout the range of R. filifolia, R. fuscoides, and R. harperi. We used Principle Components Analysis (PCA) to explore the morphological dataset. To test the hypothesis of a geographic cline, we used linear regression to asses the explanatory strength of the coordinate data for each morphological character. There was no significant trend in morphological characters by latitude. The PCA results show clear separation between R. filifolia and R. harperi. Further work is in progress to address the status of R. fuscoides and additional problems within the complex.

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1 - Delaware State University, Claude E. Phillips Herbarium, Department of Agriculture and Natural Resources, 1200 N. DuPont Highway, Dover, DE, 19901, USA
2 - New York Botanical Garden, 2900 Southern Boulevard, Bronx, NY, 10458, USA

geographic cline

Presentation Type: Oral Paper:Papers for BSA Sections
Session: 68
Location: Cottonwood D/Snowbird Center
Date: Wednesday, July 29th, 2009
Time: 2:30 PM
Number: 68007
Abstract ID:794