Both sexes have an almost straight, entirely black bill and little or no white post-ocular spot.

The genus Thalurania was introduced in 1848 by the English ornithologist John Gould.

[1] Gould did not specify a type species but this was designated as the fork-tailed woodnymph by George Robert Gray in 1855.

It is reportedly restricted to Valle del Cauca in Colombia and lacks iridescence to its crown, but at present no official authority (beyond the describers themselves) recognize it as valid.

A molecular phylogenetic study published in 2014 found that Thalurania was non-monophyletic and that the Mexican woodnymph is closely related to species in the genus Eupherusa.