Bryum cryophilum Mårtensson, Kungl. Svenska Vetenskapsakad. Avh. Naturskyddsarenden. 15(2): 183. 1956

Plants in dense swelling turfs, red, red-green, or red-yellow. Stems 2-4(-6) cm, fertile stems comose, innovations evenly foliate. Leaves yellow-green to pink or red, dark red-brown with age, somewhat distant, older leaves ± imbricate, younger leaves strongly contorted to shrunken when dry, ovate, strongly concave, 0.5-3 mm, not much enlarged toward stem apex; base green, weakly decurrent; margins plane or weakly revolute in proximal 1/4, limbidium strong, in 2 or 3 rows; apex obtuse; costa percurrent or sometimes not reaching apex, apiculus absent; proximal laminal cells rectangular, 3-4:1; medial and distal cells irregular, 15-22(-25) µm wide, 2-3:1, walls thin. Specialized asexual reproduction absent. Sexual condition dioicous. Seta red, 2-4 cm, slender, straight to somewhat flexuose. Capsule yellow-brown to brown, ovate to obovate, symmetric, 2-4 mm, mouth yellow-brown; operculum conic, weakly apiculate; peristome well developed; exostome teeth yellow-brown, lamellae straight, pores absent near base along mid line; endostome not adherent to exostome, basal membrane 1/2-2/3 exostome height, segments with ovate perforations, cilia long, appendiculate. Spores 16-20 µm, pale yellow.

Capsules mature Jul-Aug. Wet soil, rock in streams, wetlands, late melting snow beds; low to high elevations (0-2000 m); Greenland; Alta., B.C., N.W.T., Nunavut, Yukon; Alaska; Eurasia (arctic regions, India, Mongolia, Nepal).

Ptychostomum cryophilum is distinguished by the densely compact red turfs, ovate concave leaves, and weak costae. The costae are red; the proximal laminal cells are narrower than the more distal cells.