Plunkett, Gregory , Nicolas, Antoine .
Phylogenetic relationships in the Bowlesia Group of Apiaceae subfamily Azorelloideae.
Subfamily Azorelloideae now includes the majority of umbelliferous genera formerly placed in the polyphyletic subfamily Hydrocotyloideae. The azorelloids form three large clades,informally referred to as the Azorella, Asteriscium, and Bowlesia groups, and more than half of these are either polyphyletic, paraphyletic, or fall within a paraphyletic group. The exception to this trend is the Bowlesia group (Bowlesia, Bolax,Dichosciadium, Drusa, and Homalocarpus),where the genera are either monophyletic or monotypic. The group is united by disctinctive indument,particularly stellate and/or glochidiate trichomes (except in Dichosciadium,where they are unbranched). The greatest diversity of species is found in South America (Bowlesia, Homalocarpus, Bolax), but Bowlesia extends north into southern North America, while Dichosciadiumis endemic to Australia, and Drusa to northern Africa. Preliminary molecular results also indicate that there are two very distinctive subgroups of Bowlesia,corresponding roughly to the presence or absence of glochidiate trichomes on the mericarps. Levels of genetic distance between these two clades approach or exceed that characterizing generic-level clades elsewhere in the Bowlesia group(e.g., in Homolocarpus and Bolax), suggesting that this distinction may warrant taxonomic recognition. The fruits of Bowlesia are character-rich, and some features suggest ecological adaptations that may be prone to convergence [e.g., fruits with air-chambers or with heteromorphic mericarps (one glochidiate, the other smooth)], suggesting adaptations for fruit dispersal. All species of Bowlesia have stellatetrichomes, but the structure of these trichomes differs. The placement of B.uncinata is of particular interest. This species is placed as sister to the non-glochidiate species, but has structures traditionally interpreted as glochids. These structures differ from those found in other glochidiate species in shaft diameter and the number and surface of the branches. Given the placement of B. uncinata with the non-glochidiate subclade, its glochids may represent either a plesiomorphy (subsequently lost in non-glochidiate species) or an independent derivation of this feature (possibly by elaboration of the stellate trichomes).
Log in to add this item to your schedule
1 - New York Botanical Garden, Cullman Program For Molecular Systematics, 2900 Southern Blvd., Bronx, NY, 10458-5126, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Franklin A/Hyatt
Date: Monday, July 9th, 2012
Time: 9:15 AM