Systematics/Phytogeography / Taxonomie/ Section
Swenson, Ulf , Lowry II, Porter P. , Munzinger, Jérôme , Rydin, Catarina , Bartish, Igor .
Phylogeny and generic limits in the non-staminode group of New Caledonian Sapotaceae: evidence of multiple origins of the anisomerous flower.
Traditional generic limits within the Niemeyera complex of Sapotaceae (Chrysophylloideae) occurring in Australia and New Caledonia do not correspond to natural groups. Previous analyses using nuclear DNA and morphology have shown that the two genera Ochrothallus and Pycnandra are polyphyletic, but resolution and group support have been low. Two of the most widely used characters employed to distinguish taxa within this group are the anisomerous flower and the number of stamens inserted opposite each corolla lobe. Based on an almost complete sample of taxa, we used Bayesian inference and parsimony jackknifing to analyze a dataset of both nuclear ribosomal (ETS, ITS) and chloroplast (trnH-psbA, trnS-G) sequence data, gaps coded as binary characters, and morphology. Our phylogenetic hypothesis improves the current understanding of this group and confirms the polyphyly of Ochrothallus and Pycnandra. From combined analyses of morphology and molecular datasets, it is clear that morphology is highly homoplasious and introduce phylogenetic noise in one part of the phylogeny rather than phylogenetic structure. Also, the anisomerous flower and changes in the number of stamens have evolved multiple times within the group, rendering these features of little taxonomic value. By contrast, the presence, absence, and type of trichomes on several organs convey more phylogenetic information than originally expected. Our phylogenetic hypotheses provide an initial basis for developing a new generic classification of the complex. Several clades correspond to previously published genera endemic to New Caledonia (Achradotypus, Leptostylis, Pycnandra, Sebertia), but circumscriptions must be significantly changed to render them monophyletic. But most important, it is now possible to describe about 20 newly identified species, place them in appropriate genera, and give them urgently needed conservation assessments because many species are range-restricted and likely threatened.
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1 - Swedish Museum of Natural History, Department of Phanerogamic Botany, P.O. Box 50007, Stockholm, SE-104 05, Sweden
2 - Muséum National d'Histoire Naturelle, Systématique et Evolution, USM 0602 Taxonomie et Collections, 16, rue Buffon, Paris, 75005, France
3 - Centre IRD de Nouméa, Laboratoire de Botanique, Nouméa, B. P. A5 98848, New Caledonia
4 - Stockholm University, Department of Botany, Lilla Frescativägen 5, Stockholm, SE-10691, Sweden
5 - Université de Rennes, Ecosystèmes - Biodiversité - Evolution, 263 Avenue du Général Leclerc, Rennes, 35042, France
Presentation Type: Oral Paper:Papers for Sections
Location: Room 3/Woodward
Date: Monday, July 28th, 2008
Time: 2:45 PM