Further phylogenetic studies in Apiaceae tribe Oenantheae Dumort.: Generic level relationships and resolution within the North American endemics-clade

DOWNIE, S. R., KATZ-DOWNIE, D. S., SPALIK, K., LEE, C., FEIST, M. A., CALVIÑO, C. I., BONE, T., SUN, F-J.

Viena, Austria

Simposio; V Apiales Symposium; 2005

Previously, we presented preliminary results of phylogenetic analyses of nuclear rDNA ITS sequences to circumscribe Apiaceae tribe Oenantheae Dumort. and to reveal provisional generic-level relationships. Seventeen genera were recognized within the tribe, with four of these not monophyletic (Berula, Bifora, Cryptotaenia, and Sium). Intergeneric relationships were unresolved or only poorly supported. North American representatives of eight genera (Bifora, Cynosciadium, Daucosma, Lilaeopsis, Limnosciadium, Neogoezia, Ptilimnium, and Trepocarpus), of which six genera are endemic to the USA, comprised a strongly supported monophyletic group; however, their rapid rate of molecular evolution, paralleling their great morphological diversity (such as the “rachis-leaf” habit of some species in several genera), confounded interpretation of relationships. Herein, we present results of an expanded ITS investigation, as well as results obtained from phylogenetic analysis of DNA sequences from the more conservatively evolving chloroplast DNA trnQ-rps16-trnK region for approximately the same set of taxa as our previous ITS study, to gain a greater phylogenetic understanding of the tribe and insight into patterns of morphological character evolution. Greater clarification of relationships is achieved, additional genera are found to be polyphyletic, nomenclatural changes are implemented, and evidence is obtained suggesting that the rachis-leaf habit is likely a synapomorphy, uniting species from at least two genera.