Systematics

Two subspecies usually recognized (Blake 1977, Stresemann and Amadon 1979, Bierregaard 1994, Ferguson-Lees and Christie 2001):

australis Swann 1922; type locality Chubut, Argentina

Occurs in the Andes from Venezuela south to Chile and Tierra del Fuego, and in lowlands of western Peru and east of the Andes to Buenos Aires, Argentina.

Similar to nominate melanoleucus, but belly always barred, narrowly and evenly, with dusky.

melanoleucus (Vieillot 1819); type locality Paraguay

Occurs from eastern Argentina (south to Santa Fe, Entre Ríos, and Buenos Aires) east through Paraguay, Uruguay, and eastern Brazil.

See Detailed Description.

There has been considerable nomenclatural confusion over the name for this species. Some authors (e.g. Hellmayr and Conover 1949) identify Spizaëtus fuscescens Vieillot (1819: 55) as the type of this species, rather than Spizaëtus melanoleucus Vieillot (1819: 57). Most authors, however, follow Amadon (1963) in using the species name melanoleucus.

Hellmayr and Conover (1949) also included melanoleucus in Buteo. Most authorities, however, separated this species in the genus Geranoaetus, which usually was considered to be monotypic (e.g. Peters 1931, Stresemann and Amadon 1979, Bierregaard 1994). Phylogenetic analysis of DNA sequence data, from both mitochondrial and nuclear genes, indicates that melanoleucus forms a clade with two species formerly included in Buteo, polyosoma (Variable Hawk) and albicaudatus (White-tailed Hawk); within this group, melanoleucus is sister to polyosoma, and albicaudatus is basal to this pair (Reising et al., 2003, Amaral et al. 2009). Consequently, polyosoma and albicaudatus now also are classified with melanoleucus in Geranoaetus (Amaral et al. 2010).