Barbula acuta (Brid.) Brid., Muscol. Recent. Suppl. 4: 96. 1919. Didymodon icmadophila auct. non (Schimp. ex C. Müll.) Saito, J. Hattori Bot. Lab. 39: 519. 1975.

Plants small, ca. 5–10 mm high, greenish to brown, in dense tufts. Stems usually erect, simple; central strand well developed. Leaves tightly appressed when dry, erect-spreading when moist, broadly ovate-lanceolate, 1.3–1.7 mm x 0.60–0.65 mm; margins nearly revolute throughout; costa stout, excurrent in a short awn; upper leaf cells rounded or rounded-quadrate, ca. 6–10 µm wide, rather thin-walled, with 2–4 blunt papillae in each cell; basal cells enlarged, oblong-ovate, thin-walled, smooth, hyaline, yellowish green. Setae erect, 6–11 mm long; capsules shortly cylindrical, 1.2–1.6 mm long; annuli developed, narrow, persistent; opercula obliquely conic-rostrate; peristome erect, irregularly bifid, fragile, pale-reddish. Calyptrae cucullate, smooth. Spores 10–15 µm in diameter, pale brownish green, smooth to finely granulate.

Type. Europe.

Chinese specimens examined: GUANGXI: Rong-shui Co., X.-L. He 5506 (PE). HEBEI: Wei Co., Xiao Wu-tai Shan, Y.-S. Zhao 46309 (HKAS, PE). HUBEI: Sheng-nong-jia, P.-C. Wu 76268b (PE).

Habitat: on rocks or thin soil over rocks; Distribution: China, Japan, Mongolia, Central Asia, Europe, North America, and northern Africa.

Illustrations: Saito 1975 (Fig. 56, 1–14).