Molecular phylogenetics of the giant genus Croton and tribe Crotoneae (Euphorbiaceae sensu stricto) using its and trnL-trnF DNA sequence data

Parsimony, likelihood, and Bayesian analyses of nuclear ITS and plastid trnL-F DNA sequence data are presented tor the giant genus Croton (Euphorbiaceae S.S.) and related taxa. Sampling comprises 88 taxa, including 78 of the estimated 1223 species and 29 of the 40 sections previously recognized of Croton, It also includes the satellite genus Moacroton and genera formerly placed in tribe Crotoneae. Croton and ail sampled segregate genera form a monophyletic group sister to Brasiliocroton, with (lie exception of Croton sect. Astraea, which is reinstated to the genus Astraea. A small clade including Moacroton, Croton alahamensis, and C, olivaceus is sister to all other Croton species sampled. The remaining Croton species fall into three major clades. One of these is entirely New World, corresponding to sections Cyclostigma. Cascarilla, and Velamea sensu Webster. The second is entirely Old World anti is to a third, also entirely New World clade, which is composed of it least 13 of Webster's sections of Croton. This study establishes a phylogenetic framework for future studies in the hyper-diverse genus Croton. indicates a New World origin for the genus, and will soon be used to evaluate wood anatomical, cytological, and morphological data in the Crotoneac tribe.