Further Support for the Crotoneae Phylogeny: A New Species of Brasiliocroton (Euphorbiaceae) Based on Morphological, Geographical, and Molecular Evidence

Brasiliocroton muricatus is a new species from eastern Brazil that is described, illustrated, and placed in a phylogenetic context. It is only the second known species of Brasiliocroton. Its phylogenetic position was inferred based on sequences from the nrITS and plastid trnL-F markers, using a sampling of closely related genera in tribe Crotoneae. Brasiliocroton muricatus was recovered within tribe Crotoneae, forming a clade with B. mamoninha. This clade is in turn sister to the large genus Croton, giving additional support to previous phylogenetic studies including B. mamoninha. The most obvious morphological characters distinguishing the new species from B. mamoninha are the unisexual, axillary inflorescences and the smaller fruits with muricate surface and white, stellate trichomes, as opposed to bisexual, terminal inflorescences and bigger fruits with smooth surface and ochraceous to brown dendritic trichomes in B. mamoninha. Both species of Brasiliocroton have the filaments of the staminate flowers erect in bud, which is the main character state distinguishing them from the closely related Croton and Astraea. Additional morphological features distinguishing Brasiliocroton and Croton from the rest of tribe Crotoneae are also discussed.