Systematics

At least six subspecies of Herpetotheres cachinnans have been described, but perhaps as few as two are recognizable (Hellmayr and Conover 1949, Blake 1977, Dickinson and Remsen 2013):

cachinnans, described as Falco cachinnans (Linneaus 1758); type locality "South America", restricted to Surinam by Berlepsch (1908)

Occurs throughout most of Central America, and South America east of the Andes. Includes chapmani Bangs and Penard 1918, excubitor van Rossem 1938, maestus Bangs and Noble 1918, and queribundus Bangs and Penard 1919.

See Detailed Description.

fulvescens, described as Herpetotheres cachinnans fulvescens Chapman 1915

Occurs from the Pacific slope of eastern Panama south along the Pacific coast to northwestern Peru.

Similar to cachinnans, but "definitely darker and more intensely colored, especially on the crown and undersurface, where generally cinnamon buff, instead of buffy white; average size smaller" (Blake 1977: 365).

Phylogenetic analysis of syringeal morphology suggested that Falconidae consistes of three clade: the caracaras (Daptrius, Ibycter, Caracara, Milvago, and Phalcoboenus); falcons (Falco, Poliohierax, Spiziapteryx, and Microhierax) and Herpetotheres); and the forest-falcons (Micrastur) (Griffiths 1994). Within the falcon group, Herpetotheres was identified as basal to all but Polihierax (Griffiths 1994).

A somewhat different set of relationships emerges, however, when genetic data (DNA sequences from mitochondrial and nuclear genes) is analyzed phylogenetically in combination with the syringeal characters (Griffiths 1999, Griffiths et al. 2004). Incorporation of the genetic data indicates that Herpetotheres is sister to Micrastur, and that the Herpetotheres/Micrastur clade in turn is sister to the caracara and falcon clades (Griffiths 1999, Griffiths et al. 2004).