We use data from the internal transcribed spacer (ITS) region of the nuclear rDNA cistron and the chloroplast psbA–trnH intergenic spacer to reconstruct the phylogenetic relationships among southern African species of Euphorbia. The results indicate that major re–organization is necessary of the groupings within Euphorbia that have been recognised in the past, since most of them turn out to be polyphyletic. Furthermore, in its present circumscription, Euphorbia itself is not monophyletic, nor do the southern African species form a monophyletic group. Both datasets show that the southern African species fall into four major groups, which we recognise as subgenera: Chamaesyce Raf., Esula Pers., Euphorbia and Rhizanthium (Boiss.) Wheeler. To accommodate the southern African species, subg. Chamaesyce is divided into sect. Chamaesyce, sect. Frondosae Bruyns, sect. nov., sect. Articulofruticosae Bruyns, sect. nov. and sect. Espinosae Pax & Hoffm. Subgenus Euphorbia is divided into sect. Euphorbia, sect. Monadenium (Pax) Bruyns, sect. Goniostema H. Baill. ex Boiss. and sect. Tirucalli Boiss. To re–establish the monophyly of Euphorbia, the genera Endadenium L. C. Leach, Monadenium Pax and Synadenium Boiss. are reduced to synonymy under Euphorbia subg. Euphorbia sect. Monadenium and the species are all transferred to Euphorbia. Consequently the subtribe Euphorbiinae now consists of the single, very large, very widely distributed and very diverse genus Euphorbia. Three of the subgenera (Chamaesyce, Esula, Euphorbia) are nearly cosmopolitan, showing the great age and wide extent of the radiation that has occurred within Euphorbia. The remaining subg. Rhizanthium is mainly African.
Emilia is a widely distributed, mainly African, palaeotropical genus in the tribe Senecioneae (Asteraceae). It comprises 117 species, most of which are annual herbs. Bayesian and parsimony phylogenetic analyses were performed on 51 Emilia species along with closely related genera in the Senecioneae using nuclear ITS and plastid trnL-trnF sequence data to address questions around the generic circumscription of Emilia, including the status of the similar genera Emiliella and Bafutia, assess Jeffrey's sectional classification of Emilia, and evaluate the distinctness of the morphologically similar species in the large-headed Emilia coccinea complex. Both nuclear and plastid phylogenies reveal Emilia to be paraphyletic and polyphyletic, with Bafutia and Emiliella nested within Emilia, and Jeffrey's sectional classification is not supported. The phylogenies provide additional evidence that Emilia coccinea and E. caespitosa should be synonymised, as shown by published phenetic cluster and multivariate analyses. The necessary taxonomic changes are made in this manuscript.
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