Macromitrium sullivantii Müller Hal., Bot. Zeitung (Berlin) 20: 361. 1862

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

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.

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).