Ranarivelo, Heritiana , Almeda, Frank , Fritsch, Peter W. .
Phylogenetic analysis of the Malagasy endemic genus Rousseauxia (Melastomataceae) based on morphological characters - preliminary results.
Rousseauxia is one of three endemic genera of Malagasy Melastomataceae. It comprises 15 species and ranges from the north to southeast of Madagascar. This study is the first attempt to investigate the intergeneric and intraspecific relationships of Rousseauxia using phylogenetic methods. In the most recent synoptic treatment of the genus, Jacques-Felix recognized Rousseauxia as a distinct genus and provided a rationale for its separation from Osbeckia, which is restricted to India and eastern Asia. We performed a cladistic analysis of the genus based on a detailed analysis of 70 vegetative and reproductive characters. Type specimens for all described taxa were studied and scored. All species of Amphorocalyx and Dionycha (except boinensis) were used as outgroups and 12 taxa of Osbeckia were added to the ingroup. Our analysis produced three most parsimonious trees. In the consensus tree, Rousseauxia appears to be monophyletic but with a weak bootstrap support. Rousseauxia is clearly not nested in Osbeckia, which forms a monophyletic clade with strong support. Within Rousseauxia there are two major clades: one composed of marojejensis, madagascariensis and tamatavensis and one composed of the remaining species. The latter is subdivided into two distinct clades: one comprising chrysophylla, humbertii and minimifolia and one comprising glauca, gracilis, dionychoides, andringitrensis, cistoides, aurata and mandrarensis. Only the first major clade shows good support. However, a sister group relationship between several species is strongly supported. The clade comprising all the R. marojejensis subspecies has good support but shows an unresolved polytomy. A further biogeographical analysis will be performed to understand the restriction of Rousseauxia to some particular areas of Madagascar and its correlation with the distribution of the two other endemic genera. The results will be valuable for the ongoing project to extend protected areas in Madagascar.
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1 - California Academy of Sciences, Department of Botany, 55 Music Concourse Drive Golden Gate Park, San Francisco, California, 94118, USA
Presentation Type: Poster:Posters for BSA Sections
Location: Event Tent/Cliff Lodge
Date: Monday, July 27th, 2009
Time: 5:30 PM