The main objectives of the study are to address questions about the monophyly of the five subtribes of Cocoeae; the closest relatives of Cocos nucifera; and the evolution of endocarps. Cocoeae, with 20 genera and nearly 200 species, contain several economically important plants including Cocos nucifera (coconut), Elaeis guineensis (African oil-palm), Attalea cohune (babaçu) and Bactris gasipaes (peach palm). Despite the economic importance of palms in general, and of the coconut in particular, we know little about their phylogenetic history. The generic level phylogeny of Cocoeae is based on analyses of sequences of the fourth intron of the nuclear gene, phosphoribulose kinase. 40 taxa were sampled in total including members of the 20 genera. Cocoeae fall into two major clades: the spiny and non-spiny clades. The spiny cocosoids (66% bootstrap support) include the Bactridinae and Elaedinae. A surprising result is the placement of Elaeis guineensis and Elaeis oleifera within the spiny group. The monotypic Gastrococos crispa (Cuba) is found to be sister to Acrocomia (100%) differing only by 2 mutations. Bactris is paraphyletic. The non-spiny cocosoids, include subtribes Beccariophoenicae, Butiinae and Attaleinae (100%). Cocos nucifera falls within this group but its closest relative is unresolved in the strict consensus tree. Syagrus, currently with 30 taxa, appears to be paraphyletic. The two Madagascan monotypic cocosoids, Beccariophoenix madagascariensis and Voaniola gerardii,(n=298!) were found to be successively basal in this clade. Morphologically, Cocoeae are characterized by having the synapomorphy of presence of three or more pores or “eyes” on the endocarp. Variation in the morphology of their bony endocarps will be optimized on the most parsimonious tree in order to reconstruct endocarp character evolution. Fossil Cocoeae are known from Australia, Easter Island, India and New Zealand. They will be placed on the nodes to estimate the time of divergence of the clades.

Key words: phosphoribulose kinase, Cocoeae, Cocos nucifera, fossils, Palmae, phylogeny