Two subspecies recognized:
parkeri, described as Metallura theresiae parkeri Graves 1981; type locality Cordillera Colán, Amazonas, Peru.
Known only from the Cordillera Colán, Amazonas, Peru.
"Males and females of parkeri have, respectively, dull bronze and dull green crowns, auriculars, and sides of throat and differ from nominate theresiae in lacking intense coppery red reflections on these parts" (Graves 1981). In addition, the undersurface of the tail is brighter, more golden green (Fjeldså and Krabbe 1990), although perhaps this character exhibits clinal variation, as the rectrices of the type of rubriginosa, from southern Amazonas, are described as "golden green" (Cory 1913). Subspecies parkeri was named after Theodore A. Parker III "in recognition of his extensive contributions to our knowledge of neotropical birds" (Graves 1981).
theresiae, described as Metallura theresiae Simon 1902; type locality Tayabamba [La Libertad], Peru
Occurs from southern Amazonas south to the Cordillera Carpish in central Huánuco, Peru.
See Detailed Description. Includes rubriginosa (Cory 1913), from southern Amazonas.
Metallura theresiae forms a superspecies with Metallura williami (Viridian Metaltail), Metallura baroni (Violet-throated Metaltail), Metallura odomae (Neblina Metaltail), Metallura eupogon (Fire-throated Metaltail), and Metallura aeneocauda (Scaled Metaltail) (Graves 1980, Heindl and Schuchmann 1998, Heindl 1999). Within this group, theresiae may be sister to eupogon (García-Moreno et al. 1999).
Phylogenetic analysis of DNA sequence data, from both mitochondrial and nuclear genes, 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). Metallura is a member of the coquette clade (McGuire et al. 2009). Genera that are documented as belonging to the coquette clade are Adelomyia, Aglaiocercus, Chalcostigma, Discosura, Heliangelus,
Lesbia, Lophornis, Opisthoprora, Oreonympha, Oreotrochilus, Oxypogon, Phlogophilus, Ramphomicron, and Sephanoides (McGuire et al. 2007, 2009). Additional genera that probably belong to the coquette clade are Polyonymus, Sappho, and Taphrolesbia (McGuire et al. 2009).