Weissia breutelii C. Müll., Syn. Musc. Frond. 1: 664. 1849.
Hymenostomum breutelii (C. Müll.) Kindb., Enum. Bryin. Exot. 91. 1889. Protologue: Virgin Islands. Ex insula antillarum St. Thomas dicta reculit Breutel.
Weissia senocarpa C. Müll., Syn. Musc. Frond. 2: 633. 1851. Gymnostomum senocarpum (C. Müll.) Jaeg., Ber. Thätigk. St. Gallischen Naturwiss. Ges. 1869–70: 280. 1870. Hymenostomum senocarpum (C. Müll.) Par., Index Bryol. 597. 1895. Protologue: Costa Rica. America centralis, Costa Rica, reg. montosa, inter 5000–8000 ped. elevationis, mens. Martii 1848, legit A. S. Oersted. (NY).
Plants small, dark-green to yellow-green above, brown below, in dense mats or tufts, 2.5–5 mm high. Stems red, sparsely and irregularly branched, hyalodermis weakly developed, central strand well-developed; rhizoids sparse red, smooth to roughened. Leaves 1.2–2.0 mm long, linear-lanceolate to lanceolate, ovate to oblong and weakly clasping at base, erect at base, crisped and spirally contorted above when dry, erect-flexuose to erect-spreading when wet; apices acuminate, mucronate; lamina unistratose, firm or occasionally fragile; margins entire, strongly involute above the base to the apex; costa stoutly excurrent, broad at base (50–60 μm), cells on ventral surface quadrate, guide cells and two stereid bands well-developed, ventral surface layer enlarged, bulging-mammillose or papillose; upper cells rounded to quadrate, 6–11 μm long, thick-walled, dorsal surface, plane to weakly bulging, smooth, ventral surface bulging-mammillose or pluripapillose with 4–6 bifid papillae, basal cells narrowly rectangular, thick- or thin-walled, yellow or hyaline, smooth, 20–50 x 6–10 μm, outer basal cells hyaline, thin-walled, not noticeably running up the margins in a v-shaped pattern. Autoicous (?). Intact sporophytes not seen in Central America. Setae long, straight, slender, yellow. Capsules symmetric, erect or somewhat inclined, ovate to ellipsoid; opercula long-rostrate; annuli lacking; peristome lacking, narrow mouth of capsule usually covered by fugacious membrane developed from columella. Calyptra cucullate, reaching middle of capsule (Crum & Steere 1957).