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.
Branches and trunks of trees. 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.