Trichostomum pygmaeum Bartr., Bryologist 49: 112. 1946.

Protologue. Guatemala. Alta Verapaz: along Río Icvolay, north and northwest of Finca Cubilgüitz to Quebrada Diabalo, alt. 300–350 m, Steyermark 44770 (F) 

Plants small, yellow-green, in tufts, 1–2 mm high. Stems red, hyalodermis present, central strand weakly developed; rhizoids sparse. Leaves 0.5–1.4 mm long, oblong-lanceolate, erect to spreading at base, erect-incurved, crisped when dry, spreading to spreading-recurved when wet; apices obtuse, shortly mucronate; lamina unistratose; margins papillose-crenulate, plane to erect; costa percurrent to subpercurrent, guide cells and two stereid bands present, ventral surface layer enlarged; upper cells quadrate, 6–8 μm wide, firm-walled, densely pluripapillose, basal cells rectangular, smooth, lax-walled or firm-walled, 8–20 x 6–8 μm, outer basal cells weakly or not running up the margins in a v-shaped pattern. Dioicous. Setae 1 per perichaetium, 4 mm long, yellow. Capsules cylindrical, erect, 1 mm long, smooth when dry; opercula rostrate, 0.6 mm long; annuli revoluble, of 1–2 rows of vesiculose cells; peristome teeth 16 reddish yellow, erect, divided nearly to the base into filiform, spicuose segments, basal member short, yellow. Spores 8–10 μm, smooth. Calyptra not seen.