Systematics

Monotypic, no variation throughout its range.

Plumbeous Kite (Ictinia plumbea) and Mississippi Kite (Ictinia mississippiensis) comprise the only members of the genus Ictinia. Sutton (1944) classified mississippiensis as a subspecies of plumbea, but most authorities recognize each as a species. Some authorities (Thiollay 1994) consider the two to form a superspecies.

Accipitridae encompasses 217 species and includes the hawks, eagles, Old World vultures, and kites. On the basis of morphological data, three clades of kites traditionally were recognized: Milvinae (including Ictinia), Elaninae and Perninae. Phylogenetic analyses of DNA sequence data, from both nuclear and mitochondrial genesMolecular analyses, however, reveal the Perninae and Milvinae subfamilies to be polyphyletic (Lerner et al. 2005, Griffiths et al. 2007), and that many buteoine taxa are embedded within kites. The affinities of Ictinia within this radiation are not yet established, however. Lerner et al. (2005) place Ictinia as basal to a clade that includes Geranospiza, Rostrhamus, Buteogallus, Rupornis, Pseudastur, Parabuteo, Buteo, and Leucopternis. Griffiths et al. (2007) place Ictinia within a radiation that includes many of the same taxa, but identify Ictinia as sister to Butastur (an Old World genus).

A fossil of the distal half of a tarsometatarsus was collected in Sonora, Mexico in recent years, marking the first discovery ever made of an Ictinia fossil. The fossil specimen was identified as belonging to the genus Ictinia, instead of other small accipitrids in the New World, by a combination of several factors including a relatively long and wide foramen vasculare distale and a wide Trochlea metatarsi II (which, for example, differentiated it from Elanus, Harpagus, and Accipiter). The tarsometatarsus specimen is larger than any available specimens of the two Ictinia species, Plumbeous and Mississippi, living today. Because the two species can not be distinguished from one another merely by their distal tarsometatarsi, it is unknown whether the recently discovered fossil is a record of the Plumbeous or Mississippi Kite. It should be noted, however, that there are no modern records for the presence of either of these species in Sonora (Steadman 2010).