1. Pterygoneurum ovatum (Hedw.) Dix., Rev. Bryol. Lichenol. 6:96. 1934; Gymnostomum ovatum Hedw., Sp. Musc. Frond. 31. 2 f. 1–3. 1801.
Plants 1–2 mm high, green or yellowish green, bulbiform, in thin tufts. Stems very short, erect, simple or branched at the base. Leaves appressed when dry, weakly spreading when moist, ovate to triangularly ovate, broadly concave, 1.0–1.7 mm long with the awn; margins plane or weakly incurved; costa ending in a smooth long awn, shorter than or nearly as long as the leaf base; with 2–4 rows of green lamellae on the ventral side of costa; upper leaf cells rounded quadrate to irregularly hexagonal, 10–14 µm in diameter, thin- to weakly thick-walled at the corners, smooth or occasionally with minute C-shaped papillae; basal cells rectangular, 26–67 µm x 10–24 µm, thin-walled, smooth. Setae 1.5–3.0 mm long; capsules shortly exserted, shortly cylindrical, 1.0–1.5 mm long, dark brown, wrinkled-plicate; annuli none; opercula conic-rostrate, with a short, oblique beak; peristome teeth absent. Calyptrae cucullate, smooth. Spores 20–30 µm in diameter, brownish, finely papillose.
Type. Germany: Leipzig.
Chinese specimens examined: NEI MONGOL: He-lan Shan (Mt.), Z.-G. Tong 1844 (PE). XINJIANG: Altai Mt., Burgin Co., Whittemore & R.-L. Zhu 4651 (MO).
Habitat: on dry soil over rocks; Distribution: China, Mongolia, Russia, North America, and northern Africa.
Illustrations: X.-L. Bai 1997 (Pl. 60, figs. 13–16).