Bryum subapiculatum Hampe, Vidensk. Meddel. Dansk Naturhist. Foren. Kjbenhavn ser. 3, 3: 51. 1872.
Protologue: Brazil. Glaziou, sub Nr. 5148.
Bryum microerythrocarpum C. Müll. & Kindb. in Macoun, Cat. Canad. Pl., Musci 6: 124. 1892. Protologue: Canada. In wet gravel, shore of Shawnigan Lake, Vancouver Island, July 1st, 1887, Macoun (MO).
Plants small to medium-sized, dull green or yellowish green, often tinged red, in loose tufts, 4–10 mm high; rhizoids moderately developed at base, papillose, with red to reddish brown, oblong to spherical, smooth gemmae, to 190 μm long. Leaves 1–2 mm long, erect when dry, erect to erect‑spreading when wet, lanceolate to oblong‑lanceolate; apices acuminate; margins plane, sometimes reflexed below, weakly bordered by several rows of somewhat narrower, long‑rectangular cells, serrulate above; costae strong, red, variously excurrent; upper cells elongate‑hexagonal, firm‑walled, 40–80 μm long, basal cells rectangular, firm‑walled, 20–80 μm long, quadrate at the lower margins. Dioicous. Setae to 15–40 mm long, reddish brown. Capsules 2–4 mm long, red, oval‑cylindrical, symmetric, pendent, neck short, narrowed and tapering to the seta; opercula 0.5 mm long, conic apiculate; exostome teeth yellow‑brown, densely papillose, endostome hyaline, lightly papillose, basal membrane to ½ of exostome teeth length, segments well-developed, narrowly perforate, cilia 2‑5, appendiculate. Spores 10 μm, nearly smooth. Calyptra not seen.
In comparison with G. dichotomum and G. radiculosum, this species has longer and narrower capsules. Sterile specimens are sometimes difficult to distinguish from G. dichotomum. The lanceolate leaves with short-excurrent costae and the reddish tubers will help to identify specimens of G. subapiculatum.
Plants small to medium-sized, loosely caespitose to caespitose, green above, yellowish brown or reddish brown below; terricolous or humicolous. Stems 3-15 mm tall, simple or branching by subperichaetial innovations, tomentose below; rhizoids reddish or reddish brown, papillose, tubers (80-)200-300 µm, red or red-brown. Leaves larger above, erect and slightly twisted dry, erect-spreading wet; lanceolate, oblong-lanceolate or elliptical, (0.8-)1.0-2.0(-2.2) mm long; apex acuminate; margins plane to recurved below, denticulate above; border generally absent. Costa mucronate to short-excurrent, occasionally reddish below, awn 0.1-0.3 mm long; in section subround, lamina inserted ventrally, ventral surface cells present, dorsal stereid band in 1-3 rows, dorsal surface cells incrassate, hydroids forming large gap between guide cells and stereid band. Upper laminal cells rhomboidal, thin-walled or occasionally incrassate, frequently narrower and incrassate towards margin, 40-68 (-98) µm long, 10-18 µm wide; basal cells rectangular to quadrate, thin-walled or incrassate, occasionally pitted. Propagulae not seen. Dioicous. Perichaetia terminal, leaves lanceolate to narrowly triangular, margins recurved. Seta 12-28 mm long, yellowish to red; capsule pendulous, oblong-cylindrical or narrowly pyriform, yellowish brown, reddish brown to red, urn 1.0-2.2 mm long, neck wrinkled when dry, frequently curved, 0.8-1.2 mm long; exothecial cells irregular in shape, incrassate, smaller towards mouth, 1-3 rows at mouth transversely elongated; peristome double, exostome teeth narrowly oblong-acuminate, bordered, yellow, orange or red-brown below, hyaline above, minutely papillose, endostome segments tapered above, broadly perforated, cilia 2-3, nodose to appendiculate, basal membrane high, yellowish, minutely papillose; operculum conical, mammillate; calyptra cucullate; spores 11-14 µm, smooth to minutely granulose.