TAXON 60 (3) • June 2011: 791–823 Van Ee & al. • Taxonomy and phylogeny of New World Croton A revised infrageneric classification and molecular phylogeny of New World Croton (Euphorbiaceae) Benjamin W. van Ee,1 Ricarda Riina2,3 & Paul E. Berry2 1 Black Hills State University Herbarium, 1200 University Street, Spearfish, South Dakota 57799, U.S.A. 2 University of Michigan Herbarium, Department of Ecology and Evolutionary Biology, 3600 Varsity Drive, Ann Arbor, Michigan 48108, U.S.A. 3 Real Jardín Botánico, CSIC, Plaza de Murillo 2, 28014 Madrid, Spain Author for correspondence: Benjamin van Ee,
[email protected] Abstract Croton (Euphorbiaceae) is a large and diverse group of plants that is most species-rich in the tropics. We update the infrageneric classification of the New World species of Croton with new evidence from phylogenetic analyses of DNA sequence data from all three genomes. The relationships of species that were previously placed in conflicting positions by nuclear and chloroplast data, such as C. cupreatus, C. poecilanthus, and C. setiger, are further resolved by adding the nuclear EMB2765 and mitochondrial rps3 genes to the molecular sampling. Analyses of rps3 reveal an accelerated rate of evolution within Croton subg. Geiseleria, the only one of the four subgenera that contains numerous herbaceous, annual species. We provide morphological descriptions, species lists, and a key to the 31 sections and 10 subsections recognized in the New World. New taxa that we describe include C. sects. Alabamenses, Argyranthemi, Cordiifolii, Corinthii, Cupreati, Luetzelburgiorum, Nubigeni, Olivacei, Pachypodi, Prisci, and C. subsects. Cubenses, Jamaicenses, and Sellowiorum. Additional transfers are made to the ranks of subgenus, section, and subsection.