4. Macrocoma (Hornschuch ex Müller Hal.) Grout, Bryologist. 47: 4. 1944. • [Greek macros, long, and kome, hair, alluding to long hairs on calyptrae of some species].
Macromitrium sect. Macrocoma Hornschuch ex Müller Hal., Bot. Zeitung (Berlin) 3: 522. 1845
Plants small, in mats. Stems creeping, branches ascending. Leaves closely erect-appressed, not contorted when dry, erect-spreading when moist, lanceolate to ovate-lanceolate, not rugose; margins entire; apex acute to narrowly obtuse [bluntly acuminate]; costa percurrent; basal laminal cells rounded to elliptic; distal cells rounded-quadrate, 7-12 µm, , smooth [papillose only over lumina]; marginal cells not distinct from basal. Sexual condition gonioautoicous; perichaetial leaves longer than branch leaves. Seta 4-6.5 mm. Capsule exserted, oblong-cylindric to fusiform, ± plicate distally or not, not constricted below mouth; stomata superficial; peristome single, of exostome or endostome; exostome teeth 16, blunt, short, papillose; or endostome basal membrane low, papillose. Calyptra mitrate, long elliptic-conic, basal lobes many, smooth, ± hairy, obscurely plicate, covering capsule. Spores isosporous, .
Species 11 (1 in the flora): se United States, Mexico, West Indies, Central America, South America, Asia, Africa, Indian Ocean Islands (Madagascar), Pacific Islands (Hawaii, New Zealand), Australia.
Characters of Macrocoma include the rounded basal laminal cells, slender, irregularly branched stems, leaves erect-appressed when dry, cylindric capsules, peristome often reduced, and calyptra long conic-elliptic. There are often rhizoids present on the abaxial costa surface.