Mestre

American Journal of Botany 92(9): 1520–1534. 2005.

MOLECULAR PHYLOGENETICS OF THE GIANT GENUS
CROTON AND TRIBE CROTONEAE (EUPHORBIACEAE
SENSU STRICTO) USING ITS AND TRNL-TRNF DNA
SEQUENCE DATA1

PAUL E. BERRY,2,5 ANDREW L. HIPP,3 KENNETH J. WURDACK,4
BENJAMIN VAN EE,2 AND RICARDA RIINA2
2
Department of Botany, University of Wisconsin–Madison, 430 Lincoln Drive, Madison, Wisconsin 53706 USA; 3The Morton
Arboretum, 4100 Illinois Route 53, Lisle, Illinois 60532-1293 USA; and 4Department of Botany and Laboratories of Analytical
Biology, Smithsonian Institution, P.O. Box 37012, NMNH MRC-166, Washington, D.C. 20013-7012 USA

Parsimony, likelihood, and Bayesian analyses of nuclear ITS and plastid trnL-F DNA sequence data are presented for 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 all sampled segregate genera form a monophyletic group sister to Brasiliocroton, with the exception of Croton sect. Astraea, which is reinstated to the genus Astraea. A small clade including Moacroton, Croton alabamensis, 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 and is sister to a third, also entirely New World clade, which is composed of at 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 Crotoneae tribe.
Key words:

Astraea; Croton; Crotoneae; Euphorbiaceae; giant