Sp. Musc. Frond. Suppl. 2(2,1): 70, plate 173 [bottom]. 1826.
Stems with branches to 1 cm, simple or 2-fid. Branch leaves 0.7–1.8 mm; basal laminal cells tuberculate or smooth, walls thick; distal cells bulging mid leaf, grading to papillose-bulging at tip. Seta dextrorse. Capsule with exothecial cells not differentiated; stomata at capsule base; exostome teeth rudimentary, delicate, pale yellow. Spores 22–32 µm, densely papillose.
Phenology: Capsules mature spring.
Habitat: Branches and trunks of trees
Elevation: low elevations
Fla., La., Miss., Mexico, West Indies, Central America, South America.
Macromitrium richardii is distinguished from other mosses with similar creeping stems and erect branches by its non-rugose, inrolled leaves and uniformly elongate basal laminal cells. The papillose-bulging distal laminal cells and autoicous sexual condition distinguish M. richardii from other species of Macromitrium in the tropical portions of its range.