Antpittas (Grallaria) have a distinctive morphology: they are plump-bodied, with short tails and notably long tarsi. Scaled Antpitta is a medium sized antpitta with a broad buffy malar stripe, grayish crown and nape, and grayish or brownish olive upperparts. The underparts are tawny, with a white or creamy crescent across the upper breast. The feathers of the crown and back are narrowly tipped with black, giving it the scaled pattern for which this species is named.
Scaled Antpitta is similar to several other species. Scaled Antpitta overlaps locally in Colombia and Ecuador with the very similar Moustached Antpitta (Grallaria alleni). These two species can be distinguished most reliably by differences in the pattern of the breast, in the width of the submoustachial streak, and in the shape and color of the bill (Krabbe and Coopmans 2000). Where these two species are sympatic, the breastof both species is mostly buff or olive brown, with feathers in the centre of the breast have a contrasting pattern. In Scaled (subspecies regulus), these feathers are pale buff (or, rarely, white), "with a noticeable difference in the distribution of white or buff between the inner and outer web of individual feathers, and with black on each side of the basal half of the shafts"; in Moustached, in contrast, these feathers are white, "with equal distribution of white on the outer and inner webs of each feather", and with the white forming "large, symmetrically elongated, narrowly black-edged spots extending onto the lower breast as thin, white to buff streaks surrounding the shafts" (Krabbe and Coopmans 2000). The submoustachial streak of Moustached is much larger than that of regulus, and always is white; the submoustachial streak of regulus is only half the width of that of Moustached, and only rarely is white (Krabbe and Coopmans 2000).
Sclaed Antpitta also is similar to Variegated Antpitta (Grallaria varia), but there is little overlap between these two species. Varieaged Antpitta is larger, with a smaller white breast patch, and with the breast and flanks more or less streaked or spotted (the flanks are unmarked in Scaled Antpitta).
Adult: Sexes similar. Forecrown with fine black scaling on a pale olive brownish background, blending to a gray crown and nape. Throat ochraceous- or tawny brown with narrow pale streaking; throat bordered by broad ochraceous or buffy malar stripes; below the throat is a crescent-shaped paler area, sometimes spotted with black to give a necklaced appearance. Loral area whitish or buffy. Auriculars olive brown with narrow streaking. Back and wing coverts similar in coloration to auriculars, with feathers edged in black to give it the scaled appearance reflected in its common name. Flight feathers and tail light brown. Under parts paler than rest, varying from pale tawny (ochraceiventris) to bright ochraceous or rufous (princeps).
No detailed information on timing or sequence of molting in Scaled Antpitta. Dickerman (1990) figures two male specimens which he considered to be in the later stages of their first pre-basic molt. Based on these and other specimens from the same Mexican locality, he described the subspecies binfordi; see discussion under Geographic variation. Dickey and van Rossem (1938) and Ryder and Wolfe (2009) suggest that, like other Grallaria, Scaled Antpittas go through only a partial preformative molt.
Iris: dark brown
Orbital skin: blue-gray
Bill: maxilla black, mandible grayish
Tarsi and toes: pinkish- or bluish gray
Total length: 15 cm (Fjeldså and Krabbe 1990); 16-16.5 cm (Ridgely and Tudor 1994); 16.5 cm (Davis 1972): 17 cm (Angehr & Dean 2010); 18 cm (Meyer de Schauensee and Phelps 1978, Hilty and Brown 1986, Garrigues and Dean 2007); 18-18.5 (Meyer de Schauensee 1964); 19 cm (Blake 1953, Herklots 1961, Edwards 1972, French 1973); 20.3 (Edwards 1989)
Linear measurements (mm):
aripoensis (Hellmayr and von Seilern 1912): adult male – Bill 33-34; wing 102-105; tail 32-36
adult female – Bill 32-33; wing 101-105; tail 34-37
princeps (Sclater and Salvin 1869): bill 33; wing 109; tail 43
chocoensis (Chapman 1917): culmen 22; wing 89; tail 28; tarsus 42
ochraceiventris (Nelson 1898): culmen 28; wing 114; tail 43; tarsus 47
carmelitae (Todd 1915): exposed culmen 21.5; wing 100; tail 38; tarsus 45
sororia (von Berlepsch and Stolzmann 1901): culmen 22.75; wing 107.5; tail 40.5; tarsus 45.5
roraimae (Chubb 1921): exposed culmen 23; wing 108; tail 39; tarsus 41
regulus (Sclater 1860): wing 102; tail 30; tarsus 41
male (guatimalensis, n = 1) 94.6 g (Krabbe and Schulenberg 2003)
female (chocoensis, n = 1) 95 g (Krabbe and Schulenberg 2003)
male (regulus/sororia) 69.5-86 g (Krabbe and Schulenberg 2003)
female (regulus/sororia, n = 1) 79.8 g (Krabbe and Schulenberg 2003)
unsexed average (princeps) 98 g (Krabbe and Schulenberg 2003)
unsexed average (n = 6) 94.1 g (range 77.0-116.0 g) (Dunning 1993)