Genus SCYTALOPUS Gould.
- Scytalopus Gould, Proc. Zool. Soc. Lond., 1836, 89. (Type, S. fuscus Gould = Motacilla magellanica Gmelin.)
- Sylviaxis Lesson, Rev. Zool., 1840, 274. (Type, S. guttatus Lesson = unidentified species).
- Agathopus Sclater, Proc. Zool. Soc. Lond., 1858, 69. (Type, A. micropterus Sclater = Merulaxis analis Lafresnaye?)
Small wren-like Pteroptochidæ (length about 100 to 130 mm.) with the mesorhinium compressed and slightly arched, loral feathers short, tail much shorter than wing, tarsal envelope distinctly scutellate, and hind claw strongly curved and shorter than the digit.
Bill much shorter than head (exposed culmen about as long as hallux, without claw), narrowly conoidal in lateral profile, its depth at base of exposed culmen equal to less than half the length of the latter; culmen flattened, very slightly to moderately decurved terminally, more or less distinctly depressed in middle portion, the basal half (mesorhinium) more compressed and more or less distinctly elevated or arched; gonys longer than mandibular rami, more than half as long as exposed culmen, rounded, slightly but distinctly convex; maxillary tomium more or less distinctly notched subterminally. Nostril narrowly cuneate or linear, longitudinal, overhung by a broad operculum. No rictal, frontal, nor mental bristles. Wing excessively rounded, very concave beneath; sixth, fifth, and seventh primaries longest (nearly equal in length), the tenth (outermost) more than half as long as the longest; all the remiges very broad, rather soft in texture; longest secondaries extending beyond tip of ninth primary. Tail decidedly to much shorter than wing to end of secondaries, excessively graduated, the rectrices (10 in number) very broad, soft, with webs semi-decomposed. Tarsus much less than half as long as wing (about twice as long as bill), its scutellation taxaspidean or semi-holaspidean (the outer series of plantar scutella much broader than the inner); middle toe, without claw, decidedly shorter than tarsus (about as long or slightly longer with claw); lateral toes about equal in length, reaching (without claw) to or very slightly beyond penultimate articulation of middle toe; hallux (without claw) longer than lateral toes and much stouter, its strongly arched claw shorter than the digit; outer toe united to middle toe only at extreme base, the inner toe entirely separated. Plumage compact but very soft (almost silky), that of the rump and flanks more elongated and lax.
Coloration. — Adult males nearly uniform gray or dusky, with hinder parts more or less rufescent and (usually) barred, sometimes with the forehead silvery gray, some species with throat or throat and breast white; adult females similar but duller in color and more barred; young very different, rusty or brown prevailing, conspicuously barred.
Nidification. — "The nest is placed in a mass of moss on a bank; it is also composed entirely of moss. The female lays two eggs, large for the size of the bird, and white." (S. magellanicus Salmon, Proc. Zool. Soc. Lond., 1879, 528.)
Range. — High mountains of Costa Rica to Falkland Islands, southern Chile and Argentina, southeastern Brazil, and mountains of Venezuela.
(About eighteen species and subspecies known.) SCYTALOPUS ARGENTIFRONS Ridgway.
SILVERY-FRONTED SCYTALOPUS.
Adult male. — Forehead and superciliary region silvery gray (no. 6 or no. 7 gray[1]); rest of upper parts plain sooty black, the feathers of rump tipped, more or less distinctly, with dark rusty brown or chestnut; sides of head, anterior portion of forehead, chin, throat, and chest plain deep slate color or blackish slate, the color usually darker around eye (especially between eye and the silvery gray of superciliary region); slate color of chest gradually changing to paler, or slate-gray, on breast, this into light silvery gray (sometimes tinged with fulvous) on abdomen; sides rather darker slate color than chest; flanks, anal region, and under tail-coverts sooty black, the feathers conspicuously tipped or terminally margined with deep rusty brown or russet; maxilla brownish black, mandible more brownish; legs and feet deep horn brownish (in dried skins); length (skins), 102-114 (107.5); wing, 51.5-54 (52.9); tail, 34.5-40 (35.8); culmen, 11-12 (11.6); tarsus, 20-21 (20.8); middle toe, 16.5-17.5 (17.1).[2]
Adult female. — Similar to the adult male but gray U-shaped frontal and superciliary mark obsolete or entirely wanting; feathers of all the upper parts broadly but indistinctly margined with dark brown; gray of under parts confined to chin, throat, and chest, the whole sides, flanks and under tail-coverts very broadly margined with russet, changing to buffy cinnamon on abdomen; bill, etc., as in adult male, but mandible lighter brownish; length (skins), 109-112 (110.5); wing, 50-52 (50.8); tail, 40-41.5 (40.7); culmen, 10.5-11.5 (11); tarsus, 19.5-21 (20.3); middle toe, 16.5-17.5 (17).[3]
High mountains of Costa Rica (Volcán de Irazú; Volcán de Poás; Coliblanco) and western Panamá (Boquete; Volcán de Chiriquí).
- Scytalopus argentifrons Ridgway, Proc. U. S. Nat. Mus., xiv, no. 869, Oct. 31, 1891, 475 (Volcán de Irazú, Costa Rica; coll. U. S. Nat. Mus.); xvi, 1893, 613 (additional specimens described). — Salvin and Godman, Biol. Centr.-Am., Aves, ii, 1892, 246. — Bangs, Proc. New Engl. Zool. Club, iii, 1902, 48 (Boquete and Volcán de Chiriquí, Panamá, 5,000-7,000 ft.). — Carriker, Ann. Carnegie Mus., vi, 1910, 594 (Ujurras de Térraba, Volcán de Irazú, La Estrella de Cartago, and Volcán de Turrialba, Costa Rica; crit.; habits). — Ferry, Pub. 146, Field Mus. N. H., orn. ser., i, no. 6, 1910, 271 (Coliblanco, Costa Rica).
- [Scytalopus] argentifrons Sharpe, Hand-list, iii, 1901, 5.