Barbula perobtusa (Broth.) P.-C. Chen, Hedwigia 80: 194. 1941. Didymodon rigidulus Hedw. var. perobtusus (Broth.) Redfearn & B. C. Tan, Trop. Bryol. 10: 66. 1995. Barbula rigidula (Hedw.) Mitt. var. perobtusa Broth., Symb. Sin. 4: 41. 1929. Type. China: Yunnan, between Nujiang and Lancangjiang, Handel-Mazzetti 8441 (holotype H).

Plants small, slender, ca. 5 mm high, yellowish green to somewhat dark green, in dense tufts. Stems erect, usually branched. Leaves imbricate, appressed when dry, erect-spreading when moist, broadly ovate at the base, abruptly narrowed to a short and blunt apex; margins entire, revolute; costa stout, subpercurrent; upper leaf cells quadrate, somewhat thick-walled, sparsely unipapillose or smooth; basal cells short-rectangular, smooth, hyaline.

Type. Mongolia: Kossogol, Novyn Chore, A. Elenkin s.n.

Chinese specimens examined: HUBEI: Wu-feng Shan (Mt.), X.-W. Wu 81 (HKAS). SHAANXI: Qin-ling (Mt.), Q. Huang 19 (PE); Tai-bai Shan (Mt.), Z.-P. Wei 5083 (HKAS, WUG). XIZANG: Ban-ge Co., K.-Y. Lang 1275 (HKAS); Nie-la-mu (Nyalam) Co., J.-W. Zhang M7510 (HKAS); Ri-gaze Co., W.-H. Li 850 (HKAS); Ya-dong Co., M. Zang 634 (HKAS).

Habitat: on calcareous rocks, rocks in high mountains, or on soil walls; Distribution: China and Mongolia.

Illustrations: Pl. 120, figs. 1–6.