Plants: 2–4 mm, pale yellow green. Leaves: variously contorted when dry, ovate to oblong to obovate, imbricate, somewhat concave, mostly 1.5–2 mm; margins serrulate by projecting ends of thin-walled cells; apices acute, terminating in a 1–2-celled apiculus, costa ending 7–10 cells before the apiculus; basal laminal cells rectangular (50–70 × 18–25 µm), distal cells irregularly short- to oblong-rectangular, somewhat inflated marginally. Seta: pale yellow, 4–5 mm, straight, not hygroscopic. Capsule: yellow, elongate-cylindrical from a neck half or more the total length, 2.5–3 mm, weakly sulcate when dry and empty; exothecial cells scarcely thickened, narrowly oblong (3–4:1) near the mouth and transversely elongate in 4–6 rows proximal to the mouth; operculum conic-rounded; peristome pale brownish yellow, lanceolate with thin trabeculae proximally and terminating in a 1–2-celled hyaline evanescent tip, striate basally and nearly smooth at the tips, endostome not seen. Calyptra: cucullate, long-beaked, inflated around the capsule, large, smooth. Spores: 18–25 µm, smooth.
Mineral soils, probably in shade of rocks or in crevices. moderate to high elevations. Ariz., Mexico (Sonora).
Enthosthodon sonorae is restricted to the Sonoran Region of southwestern United States and northern Mexico.