A worldwide molecular phylogeny and classification of the leafy spurges,EuphorbiasubgenusEsula(Euphorbiaceae)

• Published in: Taxon Vol. 62; no. 2; pp. 316 - 342
• Main Authors: Riina, Ricarda, Peirson, Jess A., Geltman, Dmitry V., Molero, Julián, Frajman, Božo, Pahlevani, Amirhossein, Barres, Laia, Morawetz, Jeffery J., Salmaki, Yasaman, Zarre, Shahin, Kryukov, Aleksey, Bruyns, Peter V., Berry, Paul E.
• Format: Journal Article
• Language: English
• Published: International Association for Plant Taxonomy (IAPT) 01-04-2013
• Subjects: Appendages; Biological taxonomies; Capsules; Habitats; Herbs; Perennials; Phylogenetics; Phylogeny; Shrubs; SYSTEMATICS AND PHYLOGENY; Taxa
• ISSN: 0040-0262; 1996-8175

The leafy spurges,Euphorbiasubg.Esula, make up one of four main lineages inEuphorbia. The subgenus comprises about 480 species, most of which are annual or perennial herbs, but with a small number of dendroid shrubs and nearly leafless, pencil-stemmed succulents as well. The subgenus constitutes the primary northern temperate radiation inEuphorbia. While the subgenus is most diverse from central Asia to the Mediterranean region, members of the group also occur in Africa, in the Indo-Pacific region, and in the New World. We have assembled the largest worldwide sampling of the group to date (273 spp.), representing most of the taxonomic and geographic breadth of the subgenus. We performed phylogenetic analyses of sequence data from the nuclear ribosomal ITS and plastidndhFregions. Our individual and combined analyses produced well-resolved phylogenies that confirm many of the previously recognized clades and also establish a number of novel groupings and placements of previously enigmatic species.Euphorbiasubg.Esulahas a clear Eurasian center of diversity, and we provide evidence for four independent arrivals to the New World and three separate colonizations of tropical and southern Africa. One of the latter groups further extends to Madagascar and New Zealand, and to more isolated islands such as Réunion and Samoa. Our results confirm that the dendroid shrub and stem-succulent growth forms are derived conditions inE.subg.Esula. Stemsucculents arose twice in the subgenus and dendroid shrubs three times. Based on the molecular phylogeny, we propose a new classification forE.subg.Esulathat recognizes 21 sections (four of them newly described and two elevated from subsectional rank), and we place over 95% of the accepted species in the subgenus into this new classification.