Systematics Section / ASPT
Clark, John L. .
Phylogeny of the tribe Episcieae with an emphasis on Alloplectus, Columnea, and Drymonia (Gesneriaceae) based on morphology and molecular sequence data.
New data from morphology and DNA sequences from nuclear and chloroplast regions have shown that most of the genera in Episcieae are artificial constructs (polyphyletic groups). An emphasis on flower orientation (resupinate vs. non-resupinate) and fruit morphology (separate endocarps and exocarp) will be discussed. Several clades will be evaluated with an emphasis on the traditionally circumscribed genera of Alloplectus, Drymonia, Paradrymonia, and Columnea. The Episcieae is the most diverse neotropical tribe in the family with at least 19 genera and ca. 800 species or roughly 21% of all Gesneriaceae. Generic concepts in this tribe remain poorly defined, partly because of a simplistic use of fruit structure in delimiting genera. Two new fruit types recently discovered for this tribe are reported where there is a separation of endocarp and exocarp during fruit dehiscence. One type of fruit layer separation is demonstrated to have tardily dehiscent endocarps and a different type of separation is demonstrated to have non-dehiscent endocarps. The tardily dehiscent endocarp clade is strongly supported and comprises mostly currently circumscribed non-resupinate species of Alloplectus. The non-dehiscent endocarp clade comprises two species of Central American Drymonia. Flower resupination is discussed and reported in a clade comprising the SE Brazilian genus Nematanthus, the Caribbean taxon Alloplectus cristatus, and an Andean clade containing the type species for Alloplectus.
1 - George Washington University, Biological Sciences, 2023 G St.NW, Washington, DC, 20052, USA
Presentation Type: Paper
Location: Cottonwood A (Snowbird Center)
Date: Tuesday, August 3rd, 2004
Time: 10:00 AM