Griscom (1932) described a second subspecies, xenoura, from Honduras (type locality: Cerro Cantoral, District of Achaga, Honduras). Reportedly xenoura differed from nominate dupontii, in the adult male, "in having the chestnut cross-bars on the outer tail-feathers only half as wide, and the central tail-feathers less narrowed subterminally and less expanded at the tip; female averaging darker cinnamon-rufous below; the central rectrices usually more broadly tipped with dusky, and the tips of the outer rectriced usually buffy with little or no white, instead of mostly white with little or no buffy" (Griscom 1932: 59). This subspecies was not recognized by Peters (1945) nor by subsequent authors (e.g. Züchner 1999).
Described as Ornismya dupontii (Lesson 1832); type locality Mexico. This is the sole species of the genus Tilmatura, which was described by Reichenbach 1855. Some authors have placed dupontii in the genus Philodice (e.g. Howell and Webb 1995); Philodice currently is not recognized by most authorities, but instead is synonymized with Calliphlox.
A recent phylogenetic survey of the phylogenetic relationships of hummingbirds, based on DNA sequence data from both mitochondrial and nuclear genes, did not include samples of Tilmatura (McGuire et al. 2007, 2009). This survey 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, 2009). Tilmatura is presumed to belong to the bee clade; other genera confirmed as belonging to this clade are Archilochus, Calliphlox, Calypte, Chaetocercus, Myrtis, Rhodopis, and Selasphorus (McGuire et al. 2007), and additional genera that are assumed to belong to this clade, besides Tilmatura, are Atthis, Calothorax, Doricha, Eulidia, Mellisuga, Microstilbon, Myrmia, and Thaumastura (McGuire et al. 2009).