Abstract Detail

Systematics Section / ASPT

Applequist, Wendy L. [2], Schatz, George E. [2], Lowry II, Porter P. [1].

Molecular phylogeny of Sphaerosepalaceae and relationships of Diegodendron.

A cpDNA-based phylogeny of all available species of Sphaerosepalaceae, a Malagasy endemic family including the genera Dialyceras (3 species) and Rhopalocarpus (15 species), will be presented.  Diegodendron (Diegodendraceae), also a Malagasy endemic, has been previously argued to be closely related to Sphaerosepalaceae or to Bixaceae.  Our results, in which Diegodendron was grouped with Bixa, supported those of a previously published molecular study.  Within Rhopalocarpus, preliminary trnL-trnF sequence data suggested a correlation between phylogenetic relationships and leaf anatomy.  Leaves of Rhopalocarpus have been described as penninerved, tri- or diplinerved, or palmatinerved, in which the primary veins are often three in number, but the laterals terminate short of the apex and unusually well developed secondary veins branch pinnately from the central primary.  Penninerved species appeared as basal in our analysis; this type of venation is also seen in related taxa such as Dialyceras, as well as thymeleaceous outgroups.  A derived clade including trinerved species and the single diplinerved species was supported; the inclusion in this clade of Rhopalocarpus coriaceus (which is penninerved) was unexpected and requires further investigation.  Capuron's 1962 treatment recognized two sections and several informal groups, which were not recognized in the most recent revision; most of these groups were not supported as monophyletic.

1 - Muséum National d'Histoire Naturelle, Systématique et Evolution, USM 0602 Taxonomie et Collections, 16, rue Buffon, Paris, 75005, France
2 - Missouri Botanical Garden, PO Box 299, St. Louis, Missouri, 63166-0299, USA

Keywords:
Madagascar
Sphaerosepalaceae
Rhopalocarpus
Diegodendron.

Presentation Type: Paper
Session: 37-1
Location: Cottonwood B (Snowbird Center)
Date: Tuesday, August 3rd, 2004
Time: 2:00 PM
Abstract ID:348