19-19.5 cm. Such's Antthrush is a stout, forward-leaning ground antbird. Upperparts predominantly olive brown, tail less olivaceous with an indistinct subterminal black band and narrowly tipped buffy. Forecrown red- or buffy brown, becoming browner posteriorly, white markings on face include a post ocular streak continued in front of eye as spot. Throat white or buffy white, occasionally with some small black spots along sides. Underparts buffy white, buffier centrally and with sides streaked with black. Crissum deep buff.
As noted by Willis (1992), Such's Antthrush shares plumage features with two sympatric congeners, Rufous-tailed Antthrush (C. ruficauda) and Short-tailed Antthrush (C. campanisona). Like Rufous-tailed Antthrush, Such's has a reddish rump and tail, a small dark bill, and a reddish or buffy forecrown. Its throat is white or buffy-white with few or no dark spots on the sides. Such's differs from Rufous-tailed by having pale tips to the rectrices, and in being less patterned below, with no barring on the crissum (Ridgely and Tudor 1994). Otherwise, particularly on the underparts, the plumage of Such's Antthrush resembles that of Short-tailed Antthrush, but Short-tailed has a small black mark on the forecrown (lacking on Such's). All three species of antthrush readily are distinguished by their species specific songs.
Vigors’ (1825) brief description of C. meruloides, for which he erected the genus Chamaeza, is as follows: "C. supra brunnea, subtus rufescenti-albida, nigro longitudinaliter maculata; gulâ albâ; crisso, rectricumque apice rufescentibus". This type specimen is described in more detail by Jardine and Selby (1826) as follows: "The prevailing colour of the upper parts, the wings and tail, is dark yellowish oil-green, paler on the lower part of the back, and on the edge of the quills tinged with a greater proportion of red- dish-yellow; the throat, breast and belly are reddish-white, paler on the throat, and on the breast longitudinally marked with brownish-black spots, distributed in the same manner as those on the under parts of the common thrush; the under tail-coverts are reddish-brown ; the legs and feet are yellowish-brown; the claws are a few shades darker." This description is accompanied by a color plate, but unfortunately, it appears that the type specimens for C. meruloides have been lost (Willis 1992).
Iris: brown to reddish-brown
Tarsi and toes: dusky-brown
Total length: 19 cm (van Perlo 2009); 19-19.5 cm (Krabbe and Schulenberg 2003)
Linear measurements (from Willis 1992; mean ± SD):
male (n = 14)
wing length 90.8 mm ± 2.4
tail length 70.4 mm ± 3.8
tarsus length 38.6 mm± 1.4
culmen length 22.1 mm ± 0.9
female (n = 9, except for tarsal measurement where n = 12)
wing length 88.8 mm ± 2.3
tail length 67.2 mm ± 2.8
tarsus length 37.8 mm ± 1.3
culmen length 21.6 mm ± 1.0
Mass: 65.7-76.7 g (Krabbe and Schulenberg 2003)