Leptodontium longicaule Mitt., J. Linn. Soc., Bot. 12: 52. 1869.
Protologue: Ecuador. Andes Quitenses, in monte Pichincha (11,000 ped.), Spruce, n. 30b.
Leptodontium subgracile Ren. & Card., Bull. Soc. Roy. Bot. Belgique 31(1): 153. 1893. Protologue. Costa Rica. forèts du Barba, Pitt. no 5531 (NY).
Plants large in loose tufts or mats, yellow-green to green, to 12 cm long. Stems red, laxly ascending, hyalodermis present, sparsely radiculose, rhizoids red or whitish. Leaves well-spaced, erect or patent, spirally twisted and contorted when dry, patulous, to squarrose from an erect base when wet, ovate-lanceolate to lanceolate, 3–5 mm long, keeled above, weakly sheathing at base, decurrent; apices acute; margins recurved in lower 1/2–3/4, dentate in upper 1/4–1/3; costa subpercurrent; upper leaf cells quadrate to hexagonal, walls rounded, firm and evenly thickened, with complex, coroniform papillae centered over the lumina, 7.5–15 x 5–10 μm, inner basal cells short-rectangular to rectangular, pluripapillose, firm-walled, occasionally porose, 22.5–52.5 x 7.5–12.5 μm, outer basal leaf cells not differentiated from inner basal cells, alar cells not differentiated. Obovoid gemmae with transverse and vertical walls borne on stems. Sporophytes not known from Central America, description based on South American plants. Dioicous. Setae straight or flexuose, 1–4 per perichaetium, 10–15 mm long, yellow, becoming red-brown with age. Capsules erect, cylindrical, 2.5–3 mm long, smooth to slightly furrowed when dry; exothecial cells short-rectangular, firm-walled; stomata at base of urn; opercula erect or obliquely conic-rostrate, 0.7–1 mm long; peristome teeth linear, irregularly divided nearly to the base, red-brown, smooth to indistinctly striate. Spores 10–12.5 μm, slightly papillose. Calyptrae cucullate, smooth, 4–5 mm long.