Two subspecies usually recognized (see also Systematics):
curvipennis (Lichtenstein 1830); type locality México.
Occurs in southeastern Mexico (San Luis Potosí to Veracruz and Oaxaca)
See Detailed Description.
pampa (Lesson 1832); type locality Interior of La Plata = Guatemala.
Occurs in the Yucatan Peninsula, Belize, and northern Guatemala; includes yucatanensis (Simon 1921).
Similar to curvipennis, but bill slightly shorter, crown brighter violet, and underparts brownish gray (not pale gray or grayish white) (Ridgway 1911).
Phylogenetic relationships within Campylopterus have not been resolved. In particular, the relationship of curvipennis with Campylopterus excellens (Long-tailed Sabrewing) is not clear; excellens is not known to be sympatric with curvipennis, although the distributions of the two species closely approach one another, and the two two species are very similar. Some authors consider excellens to be a subspecies of curvipennis (Peters 1945, Züchner 1999).
Monroe (1968) questioned whether curvipennis and pampa were conspecific.
Phylogenetic analysis of DNA sequence data reveals that hummingbirds (Trochilidae) constitute nine major clades, comprising the hermits, mangos, Patagona, topazes, coquettes, brilliants, mountain-gems, bees, and emeralds (McGuire et al. 2007). Sabrewings (Campylopterus), including curvipennis, belong to the emerald clade. According to this estimate, Campylopterus is sister to a clade made up of Antillean Crested Hummingbird (Orthorhyncus cristatus) and Violet-headed Hummingbird (Klais guimeti). Presumably the genera Abeillia, Stephanoxis, and Phaeochroa also are closely related to the Onychorhynchus-Klais-Campylopterus clade (McGuire et al. 2008), but were not included among the taxa investigated in this research.