Mironia crassicuspis (Robins.) Zand., Bull. Buffalo Soc. Nat. Hist. 32: 112. 1993.

Barbula crassicuspis Robins., Bryologist 67: 446. 1964 [1965]. Morinia crassicuspis (Robins.) Zand., Bryologist 81: 557. 1978 [1979]. Protologue: Mexico. Park like area at edge of grassland, Llano de las Flores in Sierra Juarez, Oaxaca, Sharp, Dec. 21, 1962 (F, MO isotypes). 

Plants small to medium-sized, reddish green above, reddish brown below, to 25  mm high. Stems red, erect, irregularly branched, sclerodermis present, central strand well-developed, rhizoids red, smooth, at base of and scattered on stems. Leaves 2–3 mm long, sheathing at base, erect-incurved, twisted when dry, spreading-recurved when wet, oblong-lanceolate, leaf tips enlarged, thickened, caducous; apices acuminate; margins bistratose, recurved to base of caducous tips, entire, not bordered, somewhat decurrent at base; costa subpercurrent, smooth at back, ventral surface cells rectangular, pluripapillose, guide cells, small ventral substereid band, and dorsal substereid to stereid bands present, upper ventral surface layer somewhat enlarged, papillose; upper cells 4–12 x 4–10 μm, firm-walled, oblate, irregularly quadrate, to short-rectangular, densely pluripapillose by thick, c-shaped papillae, basal cells smooth to lightly pluripapillose, rectangular thin, but firm-walled, not especially bulging, 40–60 x 6–14 μm, alar cells not differentiated. Dioicous. Perichaetia terminal, perichaetial leaves sheathing with an exceptionally long, caducous apex. Sporophytes unknown.