Toll, Katherine , Whitlock, Barbara A. .
A molecular phylogeny of Micromelum (Rutaceae: Aurantioideae) and observations on floral morphology using a historical plant anatomy resource.
Micromelum includes nine species of shrubs and small trees in the citrus subfamily (Aurantioideae) of Rutaceae. It has the largest geographic range of any genus in Aurantioideae, extending from South and Southeast Asia to Australia and Oceania, with both widely distributed species and narrow endemics. At least some species of Micromelum have the unusual character of convoluted locules caused by the twisting of the radial walls of the ovary. Although twisted ovaries are often described as a generic character, it is unclear if all species of Micromelum have them. We constructed a phylogeny of Micromelum using non-coding cpDNA sequences and made observations on floral morphology using the historical Swingle Plant Anatomy Reference Collection to test the following hypotheses: (1) the widely distributed species M.minutum is monophyletic, (2) species with limited geographic ranges (e.g., M. ceylanicum) are genetically distinct from their more widely distributed relatives (e.g. M. minutum), (3) all species of Micromelum have twisted ovaries, and if not, (4) species with twisted ovaries form a monophyletic group. Relationships among specimens of M. minutum sampled are unresolved, so it is uncertain whether it is monophyletic. The narrow endemic M. ceylanicum found only in dry lowland forests of Sri Lanka appears to be genetically distinct from all other species sampled. Although twisted ovaries are often described as a defining trait of Micromelum, we observed them in only three of eight species represented in the Swingle Collection, suggesting their occurrence may be more limited than what is currently thought. Alternatively, twisting may occur in some species at later developmental stages than those observed. We compare these results to observations on two other characters important in defining Micromelum: valvate petal aestivation and oil glands at the tip of each locule.
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1 - University of Miami, Department of Biology, Coral Gables, FL, 33124, USA
2 - University Of Miami, Department Of Biology, P.O. Box 249118, CORAL GABLES, FL, 33124-0421, USA
Presentation Type: Poster:Posters for Sections
Location: Khorassan Ballroom/Chase Park Plaza
Date: Monday, July 11th, 2011
Time: 5:30 PM