Trichostomum portoricense Crum & Steere, Bryologist 59: 250. 1956.

Protologue: Puerto Rico. South of Arecibo at the Río Abajo Planting Project, W.C. Steere 6601, Feb. 22, 1940.

Trichostomum molariforme Zand., Bryologist 85: 126. 1982. Protologue: Haiti. Bois Contre near Morne la Selle, Orcutt 8479. 

Plants small, yellow-green above, brown below, in loose tufts or cushions, 10 mm high. Stems red, erect, irregularly branched, hyalodermis absent, central strand present; rhizoids sparse. Leaves 1.5–2.2 mm long, linear-lanceolate, erect or spreading at base, erect-incurved, somewhat contorted, keeled above when dry, spreading to spreading-recurved when wet; apices broadly acute to rounded, sharply mucronate; lamina unistratose, sometimes fragile; margins entire, plane, erect to weakly recurved; costa stoutly excurrent, guide cells and two stereid bands well-developed, ventral surface layer enlarged; upper cells quadrate, 7–9 μm wide, firm-walled, irregularly protuberant from both sides of the lamina, pluripapillose, the papillae fused into a thick cap, basal cells rectangular,  firm-walled, occasionally porose, 10–24 x 4–6 μm, outer basal cells not running up the margins in a v-shaped pattern. Dioicous. Setae 1 per perichaetium, 3 mm long, red-brown. Capsules cylindrical, erect, 1 mm long, sulcate when dry; opercula rostrate to long-conic, 0.7 mm long; annuli of vesiculose cells; peristome teeth 16, short, erect, yellow, smooth, basal membrane present. Spores 18–10 μm, smooth. Calyptra not seen.