Piculets (Picumnus) are very small, short tailed, and short billed woodpeckers. Speckle-chested Piculet has gray or grayish brown upperparts. The breast is black, heavily speckled with white; the belly is white, barred with black. The forecrown of the male is red; the rear crown of the male, and the entire crown of the female, is black, with numerous small white spots.
The pattern of the upperparts, including the crown, of Speckle-chested Piculet is similar to that of Ocellated Piculet (Picumnus dorbignyanus) of central Peru. Ocellated Piculet has a different pattern on the underparts (the throat and breast are buffy white, scaled with black), and the two species are not known to overlap geographically. Lafresnaye's Piculet (Picumnus lafresnayi) occurs at lower elevations than Speckle-chested; Lafresnaye's is more olive above, and yellower below, than Speckle-chested.
The following description is based on Winkler et al. (1995) and on Winkler and Christie (2002):
Adult male: Crown and nape black; feathers of fore part of crown (except for forecrown, immediately above the bill) broadly tipped red, and rear crown and nape with numerous small white spots. Lores and nasal tufts buffy white. Back and rump grayish brown, feathers with indistinct pale gray edgings and darker subterminal marks, producing a slightly scalloped pattern. Wing coverts and remiges brown, coverts with pale gray or off white tips and edges, and secondaries and tertials also edged with pale gray or off white. Rectrices blackish; the central pair has a white stripe along the inner web, and the outer two pairs of rectrices have a white subterminal area. Chin and throat white, feathers tipped black. Breast black, feathers with large, drop-shaped white spots. Belly and undertail coverts white, broadly barred black.
Adult female: Similar to male, but lacks red on crown; forecrown minutely spotted with white.
Bill: Maxilla black, with blue-gray base; mandible blue-gray with black tip
Tarsi and toes: gray
Bare part color data from Parker and Parker (1982).
Total length: 9-10 cm (Schulenberg et al. 2007), 10 cm (Winkler et al. 1995, Winkler and Christie 2002)
wing (flat): 53.7-57.5 mm
tail: 33 mm
bill (exposed culmen): 13.5-14 mm
These data from Winkler et al. (1995); the sample size is not stated, and the measurements presumably are for the sexes combined
Mass: mean 9.9 g (range 9.2-10.5 g, n = 5, sexes combined; Parker and Parker 1982).