Scaled Antpitta is a highly variable species across its considerable geographic range, with somewhere between 7 and 11 subspecies recognized (Krabbe and Schulenberg 2003). The northernmost populations have been separated from nominate guatimalensis as subspecies mexicana (Sclater 1861; Jalapa, Veracruz, Mexico) based on larger size (from nominate) and paler underparts, but recent authors (Krabbe and Schulenberg 2003), and even Sclater (1877) himself, have questioned the validity of this distinction. Sclater’s (1861) original description of mexicana, in Latin, is as follows: "Similis G. guatemalensi, sed major, colore corporis infra dilutiore, ventre albicantiore, et remigibus alarum extus rufescentioribus. Long, tota 7.5, alae 5.0, caudae 2.0, tarsi 2.1 [inches]." Dickerman (1990) proposed the most recently described subspecies of Scaled Antpitta, binfordi, from 6000 ft. on the divide between Cuernavaca and Valley of Mexico, Morelos, Mexico. Krabbe and Schulenberg (2003) chose not to recognize this subspecies pending further analysis, but acknowledged that it might prove to be a valid taxon. Dickerman (1990) described binfordi as "similar to G. g. ochraceiventris in color but with marked breast band of vertical striping," stating that "the striping extends onto the belly in the first basic plumage."
The following subspecies were recognized by Krabbe and Schulenberg (2003):
1)G. g. guatimalensis (Prévost and Des Murs 1846). The nominate subspecies is distributed from eastern and southern Mexico (from northwest Veracruz and northern Oaxaca), southward and eastward to northern Nicaragua.
The original description in Latin of Prévost and Des Murs (1846): "G. suprà brunnea; subtùs rufescens; pectoris maculis aliquot semi-collaribus nigris", was quoted from de Lafresnaye (1842) referring to a Guatemalan specimen. They expand upon this original description by saying: "Tête et derrière du cou gris de fer, chaque plume cerclée régulièrement de noir; dos, manteau et couvertures alaires brun olivâtre écaillé légèment de noir; rémiges secondaires brunes; rémiges primaires et rectrices rousses; paupières blanchâtres; tout le dessous du corps, depuis le menton jusqu'aux couvertures inférieures de la queue d'un fauve roussâtre, les plumes de la gorge offrant quelques traits écailleux noirâtres."
2)G. g. aripoensis (Hellmayr and von Seilern 1912). This is the only subspecies not confined to the mainland, found only in Trinidad. Subspecies aripoensis shares the rich, deep coloration of princeps, but lacks a dusky throat patch, has buff-colored malar stripe, and an unmarked chest.
The original description, of a "large series" collected in 1912 in Trinidad is as follows: "Nearest to G. g. regulus Scl., from the Andes of Ecuador and Western Venezuela (Mérida), but smaller, with the underparts much brighter, deeper ferruginous, and the black squamate markings of the back decidedly broader".
3)G. g. princeps (Sclater and Salvin 1869). This Central American subspecies is confined to Costa Rican and western Panama. It is more richly colored than the nominate, with heavier black scaling on the upper parts.
The original description is as follows: "Supra oleaginea, plumis nigro marginatis; pileo et collo postico valde obscurioribus et cineraceo tinctis; loris et oculorum ambitu rufescentibus: alis obscure fuscis, extus et intus castaneo limbatis: cauda omnino fuscescenti-castanea: subtus saturate ferruginea, pectore paulo obscuriore, gutturis medii plumis nigro variegatis: rostro obscure corneo, mandibulae basi albicante; pedibus corylinis".
4)G. g. chocoensis (Chapman 1917). Very similar to subspecies princeps in its richer coloration, but chocoensis is darker overall, with a more olive crown and wings, and with the lores being somewhat rusty or darker (rather than whitish). It is confined to the northern Choco bioregion, in eastern Panama and northwestern Colombia.
Chapman’s (1917) original description is based on a male from Colombia in 1912 and is as follows: "Resembling Grallaria guatimalensis princeps (Scl. and Salv.) in general color but crown more olive, back richer, wings more olive less rufous, lores mixed rusty and blackish rather than whitish; size very much smaller."
5)G. g. ochraceiventris (Nelson 1898). Subspecies ochraceiventris is endemic to southern Mexico from Jalisco eastward to western Hidalgo and from southern Guerrero to southern Oaxaca. It is significantly paler than the nominate race, in particular on the underparts. It further differs by having narrow black scaling above and lacking dusky feathers on the throat.
The original description of the type, collected in 1897 at San Sebastian, Jalisco, Mexico, is as follows: "Feathers of crown and back olive-brown, shaded with fulvous, and narrowly margined with black; sides of crown, back of orbits, and nape olive-brown with a dark ashy shade most marked on sides of crown; forehead paler or more fulvous brown. Tertiaries and secondaries dull rusty brown; outer vanes of primaries shading from dull rusty brown to dull tawny brown on outer quills; wing coverts dull brown with shaft lines and spots of dull tawny brown at tips. Under coverts and axillars pale buffy; inner webs of quills at base still paler buffy, becoming grayish brown on outer half; tail and upper tail coverts light rusty brown. Lores and malar patch pale, dull grayish-white, shaded with dingy fulvous; under eyelids blackish; ear coverts dark olive-brown washed with blackish; chin, throat, and patch on middle of breast whitish washed with fulvous; feathers bordering breast-patch scantily black tipped; sides of throat, breast (except whitish patch), chest, and flanks dingy buffy."
6)G. g. carmelitae (Todd 1915). This subspecies was originally described as a subspecies of Variegated Antpitta (G. varia), but its correct affinities were later noted by Todd and Carriker (1922), who referred to it as G. regulus carmelitae. Subspecies carmelitae is known only from northern Colombia, in the Santa Marta Mountains and Perijá Mountains, southward to northern Boyacá. It differs from G. g. regulus only in being generally darker and browner (rather than olivaceous) on the upper parts and more brownish (than ochraceous) on the underparts. Krabbe and Schulenberg (2003) considered it to be doubtfully separable from regulus.
Todd (1915) described an adult male collected in 1914 at Pueblo Viejo, Colombia as follows: "Similar to Grallaria varia varia, but smaller, and posterior lower parts darker, more cinnamon rufous."
7)G. g. sororia (Berlepsch and Stolzmann 1901). Grallaria g. sororia is confined to southern Peru, south of Cuzco, and occurs in Bolivia southward and eastward to Santa Cruz. Krabbe and Schulenberg (2003) considered it to be doubtfully separable from regulus, differing only in whiter facial markings, a grayer back, and paler underparts (but note the different Vocalizations).
The original description of the type specimen in Latin is as follows: "G. dorso pileoque anteriore brunnescenti griseo-olivaceis, pileo posteriore nuchaque griseis, plumarum apicibus nigro marginatis, marginibus in dorso lalioribus in pileo angustioribus, tectricibus auricularibus gulaque obscure olivaceo-brunneis, regione infraauriculari et regione malari albo et brunneo variis, torque juguli semilunari superiore albo, inferior nigro (plumarum apicibus nigris); pectore laleribusque corporis pallide rufescenti-brunneis maculis fuscis irregularibus vix conspicuis instructis, abdomine medio pallidiore fulvo; hypochondriis crisso tectricibusque subcaudalibus et subalaribus necnon remigum marginibus internis laete fulvorufis; alis extus rectricibusque rufescenti olivaceo-brunneis; maxilla cornea, niandibula pedibusque carneo-brunneis."
8)G. g. roraimae (Chubb 1921). This subspecies is confined to the tepui region of southern Venezuela and adjacent areas of northern Brazil and western Guyana. It is similar to regulus, but has a grayer crown.
Chubb (1921) describes this subspecies as "differ[ing] from the type of G. r. regulus in being more grey on the top of the head, nape, and hind-neck; paler and more olive-brown on the back and the dark fringes to the feathers less pronounced; paler and more cinnamon-rufous on the outer aspect of the flight-quills; ear-coverts darker; throat more streaked with white or ferruginous; fore-neck ferruginous intermixed with black, instead of uniform ochreous brown; breast, abdomen, and under tail-coverts paler and brighter ferruginous; and the larger size."
9)G. g. regulus (Sclater 1860). Sclater describes this species from a single specimen collected in Ecuador. Subspecies regulus is one of the more widely distributed subspecies, found from northwestern Colombia southward along the western slope of the Andes southward through Ecuador to Cajamarca, Peru. On the eastern Andes it is found from western Venezuela (Mérida) southward through Colombia and eastern Ecuador to central Peru. It is generally smaller than other subspecies, usually has a buffier malar stripe and facial crescent (only occasionally white in some individuals), a dusky throat, pale tawny (rarely white) striping on a dark brown breast. The underpart coloration fades to tawny on the belly and crissum.
Sclater’s original (1860) description in Latin is as follows: "Brunnescenti-olivacea, pileo cinerascentiore; dorsi plumis nigro circumcinctis; alis nigricantibus extus brunneo limbatis; cauda brevissima unicolore brunnea: subtus saturate ferruiginea, gutture et pectore nigricantiore perfusis; torque gutturali pallide cinnamomeo, hujus plumarum apicibus nigris: rostro comeo, supra obscuriore: pedibus corylinis: tectricibus subalaribus ventre concoloribus".