Cyanolyca

Abstract: The six genera of corvids endemic to the Americas (i.e., Aphelocoma, Calocitta, Cyanocitta, Cyanocorax, Cyanolyca, and Gymnorhinus) form the assemblage that most ornithologists call the New World jays. The intergeneric relationships among these six genera are explored using complete sequences from the cytochrome b gene (1,143 bp) along with 29 morphological characters. A consistent phylogenetic hypothesis was obtained when the data sets were analyzed independently or in a total evidence approach. The phylogeny presented in this paper does not corroborate the existence of two evolutionary lineages as previously proposed by Hardy (1961, 1969). The most basal genus of the New World jays is Cyanolyca, which also is supported by independent evidence on cranial anatomy. The remainder of the genera are embedded within two major clades. The most derived is formed by Cyanocitta, Aphelocoma, and Gymnorhinus, being Cyanocitta the most basal genus within this clade. Calocitta and Cyanocorax constitute the other clade. A very close relationship between these two genera is supported by bootstrap values and branch support analysis. These results corroborate the hypothesis that the Pinon Jay (Gymnorhinus cyanocephalus) is a true New World jay, and a putative relationship with nutcrackers is not supported. The phylogeny obtained is used to infer a biogeographic scenario, as well to explain the evolution of a very derived jaw articulation present only in the New World jays. The biogeographic scenario agrees with a relatively recent arrival of a corvine ancestor via Beringia, and a very rapid dispersal and radiation into the Americas.