Leaves: with basal laminal cells bulging, papillose-mammillose. Seta: dextrorse, smooth. Capsule: 1.3–2 mm; exothecial cells not or slightly differentiated; peristome consisting of low papillose membrane. Calyptra: often splitting by one cleft along one rib. se United States, Mexico, West Indies, Central America, South America, Asia, s Africa, Pacific Islands (New Zealand), Australia.

Subspecies 2 (1 in the flora). Subspecies tenuis is Old World in distribution.

Branch: leaves carinate, 0.7–1.2 mm; margins ± plane; costa prominent; laminal cells to 22 µm; distal cells bulging. Spores: 33–42 µm.

Dry mountain tops and slopes of southern Blue Ridge escarpment, trunks of Juniperus, Pinus, and Quercus. moderate elevations. Ga., N.C., S.C., Tenn., Mexico, West Indies, Central America, South America, Asia (China, Japan, Korea, Taiwan).

Subspecies sullivantii differs from other taxa in Orthotrichaceae by its slender, creeping stems with erect branches. The leaves are erect-appressed, and the basal laminal cells are rounded-quadrate. Subspecies sullivantii is closely related to a Mexican species, Macrocoma orthotrichoides (Raddi) Wijk & Margadant, which differs in having a peristome and sparsely hairy calyptra.