Proposal (233) to South American Classification Committee
Include Oroaetus isidori and Spizastur melanoleucus in Spizaetus
The proposed change would subsume both monotypic genera Oroaetus and Spizastur into Spizaetus to indicate the close relationship and monophyly of the New World hawk-eagles.
Two independent DNA sequence data studies (involving a combined three mitochondrial & four nuclear genes; Helbig et al. 2005, Lerner and Mindell 2005) concluded that Spizaetus ornatus and Oroaetus isidori are sister species, and Spizastur melanoleucus is sister to those two species. The Black Hawk-Eagle (Spizaetus tyrannus) is “basal” to the entire clade. The Old World "Spizaetus" are not sister to the New World Spizaetus (S. ornatus has priority for this generic name, as subsequently designated by Vieillot 1816). An earlier morphological data set indicated that New and Old World Spizaetus were not sisters (Jollie 1976-1977). As a result of these data, Helbig et al. (2005) formally proposed that the four New World taxa be included in Spizaetus.
Given that two independent genetic data sets, both with strong nodal support, clearly indicate that the two genera Oroaetus and Spizastur are imbedded within the New World hawk-eagle clade, I strongly support this change.
If the above taxonomic treatment is accepted then the following linear sequence should be adopted:
Helbig, A.J., A. Kocum, I. Seibol, M.J. Braun. 2005. A multi-gene phylogeny of aquiline eagles (Aves: Accipitriformes) reveals extensive paraphyly at the genus level. Molecular Phylogenetics & Evolution 35:147-164.
Jollie, M. 1976-1977. A contribution to the morphology and physiology of the Falconiformes. Evol. Theory 1, 285-298; 2, 115-300; 3, 1-141.
Lerner, H.R.L. and D.P. Mindell. 2005. Phylogeny of eagles, Old World vultures, and other Accipitridae based on nuclear and mitochondrial DNA. Molecular Phylogenetics & Evolution 37:327-346.
Mark Robbins, August 2006
Comments from Remsen: "YES. Concordant, independent data-sets make this decision noncontroversial."
Comments from Cadena: "YES. The genetic data from multiple loci in both genomes leaves no doubt that a rearrangement needs to be done, and placing these taxa in Spizaetus is necessary because S. ornatus is the type species of the genus. Although with this we would make the Spizaetus in our region a monophyletic group, the problem of the polyphyly of Spizaetus won't be solved until Old World species are transferred to a different genus."
Comments from Stiles: "YES. Both genetic and morphological data clearly support this move."
Comments from Zimmer: "YES. This doesn't resolve the problem of the relationship of Old World Spizaetus, but at least it tidies up the Neotropical picture."
Comments from Stotz: "YES. Molecular data looks clear."
Comments from Jaramillo: "YES. Superb to have independent data sets to support this, apart from the fact that it makes sense on many levels. The question of what to do with the Old World Spizastur is not our job, so that doesn't concern me other than I hope it is clarified by appropriate authorities."
Comments from Pacheco: "YES. Os dois trabalhos, de forma independente, sčo claros em apontar o mesmo melhor arranjo."