Abstract Detail

Systematics

Gostel, Morgan [1], Funk, Vicki [2], Kelloff, Carol [3], Loeuille, Benoit [4].

Pruning the ironweeds: diversity, evolution, and phylogenetic placement of the distinctive genus Distephanus (Compositae).

The taxonomic challenge in the “ironweed” tribe, Vernonieae (Compositae) has been illustrated vividly throughout its history by researchers who have ascribed a number of pejoratives to the group, from the “Vernonia problem” to “Evil Tribe”, and most recently “purgatory” conjuring images that can frighten even the most headstrong systematists. These images are manifested in extreme morphological diversity of and often continuous variation among species in the tribe. One of the most distinctive and species-rich genera in Vernonieae is the geographically widespread genus, Distephanus, which is readily distinguished from all other species in this tribe by yellow corollas and trinervate leaf venation. Recent phylogenetic studies have called the position of Distephanus in Vernonieae into question, due the unclear relationships between the small tribe Moquinieae and Vernonieae. Here we present a densely sampled molecular phylogenetic reconstruction of the genus Distephanus from across its geographic range that includes 70% of the 43 species and four molecular markers, as well as a representative sampling of African Vernonieae and Moquinieae. This work represents the largest and most well- resolved phylogeny of Distephanus to date and our results have great significance for the circumscription of Vernonieae bringing strong support to recognize that lineage as a distinct tribe and interesting insights into the biogeography and evolution of this diverse and widespread genus.

1 - Botanical Research Institute of Texas, 1700 University Dr., Botanical Research Institute of Texas, Fort Worth, TX, 76107-3400, United States
2 - DEPT OF BOTANY-NHB 166, P.O. Box 37012, Washington, DC, 20013, United States
3 - Botany MRC166, PO Box 37012, Washington, DC, 20013, United States
4 - Royal Botanic Gardens, Kew, Herbarium, Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AB, UK

Keywords:
none specified

Presentation Type: Oral Paper
Number: SYST III011
Abstract ID:717
Candidate for Awards:None