Husnotiella revoluta Card., Rev. Bryol. 36: 71. 1909.
Didymodon revolutus (Card.) Williams, Bryologist 16: 25. 1922. Protologue: Mexico. Etat de Mexico: Lecheria, murs, 1908 ([Pringle] n. 10523); Amecameca, 1908 ([Pringle] n. 10610). Etat de Morelos: près de Cuernavaca, murs, 1908 ([Pringle] no. 10531, 10636 [MO]). Etat de Hidalgo: Tula, murs en terre, 1908 ([Pringle] n. 15214). Etat de Jalisco: Guadalajara, murs, 1908 ([Pringle] n. 10574, in parte, 15231 in parte, 15233).
Plants small, dull, green to yellow-green above, brown below, in tufts, 5–10 mm high. Stems greenish yellow to yellow above, reddish yellow below, erect, sparsely and irregularly branched, hyalodermis of somewhat enlarged, thin-walled cells, central strand present; rhizoids sparse, at base of stems or scattered throughout. Axillary hairs 4–7 cells long, basal cell brown. Leaves 0.8–1.2 mm long, lingulate to elliptic or ovate, erect, imbricate-incurved when dry, wide-spreading when wet, broadly channeled on ventral surface; apices rounded-obtuse to cucullate; lamina unistratose or with bistratose areas along the margins; margins entire, recurved to revolute to near the apex; costa subpercurrent, broad, spurred above midleaf, upper surface ventral cells of costa quadrate, guide cells and single (dorsal) stereid band present, ventral surface cell layer of enlarged, bulging, papillose cells; upper and basal cells differentiated, upper cells rounded-quadrate to rhomboidal or oblate, 4–12 x 6–10 μm, firm-walled, with 1–2(–3) large papillae, interior basal cells short-rectangular, firm-walled, smooth, 10–20 x 6–8 μm, basal marginal cells quadrate to oblate, alar cells not differentiated. Dioicous. Perichaetia terminal, perigonia gemmiform. Setae smooth, 4–8 mm long, red. Capsules elliptic to cylindrical, erect, 1 mm long, smooth; exothecial cells rectangular, firm-walled; stomata in neck; opercula erect, obliquely short-rostrate, 0.5 mm long; annuli vesiculose; peristome absent to rudimentary, yellow to red-orange, basal membrane absent, teeth erect, papillose. Spores 8–11 μm, smooth. Calyptrae cucullate, 2 mm long.