Because of the lower quality of our Ateles marginatus sample, we were unable to initially amplify our target fragment in a long range PCR and, subsequently, to sequence the entire 3480 bp we obtained for most other samples. When the analyses above are repeated excluding sequence data from the NAD6 locus, the inferred phylogenies are broadly similar to those noted above. Again, A. marginatus is reconstructed as basal with 100% support in both the maximum likelihood and Bayesian analyses, as are clades comprising A. belzebuth + A. chamek and A. fusciceps + A. geoffroyi. Details of the inferred phylogeny, however, are not always identical. In the likelihood analysis, A. hybridus is joined to A. belzebuth + A. chamek in a weakly supported clade, and the relationships among A. paniscus, A. belzebuth + A. chamek + A. hybri- dus, and A. fusciceps + A. geoffroyi are unresolved. In the Bayesian analysis, the inferred branching order conforms to what was recov- ered in the likelihood analysis using all three loci, but with higher support for a clade of A. hybridus + A. paniscus + (A. fusciceps + A. geoffroyi) (Fig. 3C and D).