Didymodon rubellus Bruch & Schimp. in B.S.G., Bryol. Eur. 2: 137., pl. 185 (fasc. 29–30. Monogr. 3.1). 1846, hom. illeg. Didymodon submicrostomus Dix., Rev. Bryol. Lichénol. 7: 106. 1934. Didymodon tenii (Herz.) Broth., Nat. Pflanzenfam. ed. 2, 11: 528. 1925. Erythrophyllum tenii Herz., Hedwigia 65: 153. 1925. Trichostomum subrubellum C. Müll., Nuovo Giorn. Bot. Ital., n. ser. 5: 176. 1898. Type. China: Shaanxi (Schen-si), in monte Thaepei-san, Aug. 1896, Giraldi s.n. (isotype H).

Plants small to medium-sized, 0.5–2.0(–3.0) cm high, dark green, yellowish green to brown, or reddish brown, in loose or dense tufts. Stems erect, simple or branched, with reddish rhizoids at the base of stems; central strand present. Leaves narrowly ovate-lanceolate, slightly curved-contorted when dry, erect-spreading when moist, gradually acuminate, narrowly acute at the apex; margins nearly recurved throughout, upper margins irregularly denticulate, lower margins entire; costa strong, percurrent; upper leaf cells quadrate to hexagonal, greenish, each cell with numerous rounded or C-shaped papillae; basal cells shortly rectangular, smooth, hyaline or reddish. Paroicous or synoicous. Setae 1.0–1.5 cm long, reddish brown; capsules erect, cylindrical; peristome teeth short, straight, reddish, densely papillose; opercula shortly rostrate. Spores greenish, papillose.

Type. Europe.

Chinese specimens examined: FUJIAN: Wuyi Shan (Mt.), D.-K. Li 9270 (HKAS, SHM). GANSU: Qi-lian Shan (Mt.), D.-Z. Zhuo 761 (PE); Xing-long Shan (Mt.), D.-Z. Zhuo 27 (PE). HEBEI: Dong-ling Shan (Mt.), L.-Q. Yu 11 (PE). HEILONGJIANG: Da-hai forest district, C. Gao 1140 (HKAS, IFSBH); Yu-chun City, X.-L. Zhu 122b (PE). HUNAN: Song-zhi Co., D.-K. Li 18378 (HKAS, SHM). JIANGXI: Jing-gang Shan (Mt.), D.-K. Li 16726 (HKAS, SHM). JILIN: An-tu Co, Koponen 36845 (H), C. Gao 1325 (IFSBH). NEI MONGOL: He-lan Shan (Mt.), Z.-G. Tong 1205 (PE). QINGHAI: Xing-hai Co., F.-G. Lu 16 (PE). SHAANXI: Qingling (Mt.), Giraldi 855, 1827 (H); Tai-bai Shan (Mt.), M.-X. Zhang 144 (HKAS). SHANDONG: Tai Shan (Mt.), Y.-T. Liang 37127 (HKAS). SHANXI: Ning-wu Co., Z.-R. Wang M6a (PE). SICHUAN: Dao-cheng Co., M.-Z. Wang 81–4010 (PE); Wen-chuan Co., J.-X. Luo 3525 (PE). XINJIANG: Bogeda Feng (Mt.), J.-C. Zhao 2835 (HKAS); Wen-saituo Feng (Mt.), S.-Y. Chen 770509 (PE). XIZANG: Lang Co., M. Zang 1752 (HKAS); Mo-tuo Co., Y.-G. Su 1626 (HKAS); Zhong-ba Co., D.-D. Tao 2087 (HKAS). YUNNAN: Da-yao Co., S. Ten 70 (H); Gong-shan Co., M. Zang 3359 (HKAS); Kun-ming City, Handel-Mazzetti 776 (H); Meng-la Co., L. Zhang 467 (HKAS). ZHEJIANG: Sheng-shan island, D.-K. Li 3940 (HKAS, SHM);Yan-tang Shan (Mt.), D.-K. Li 8301 (HKAS, SHM).

Habitat: on rocks in shade, or thin soil over rocks, sometimes on rotten trees; Distribution: China, Japan, Russia, Europe, North America, Australia, and northern Africa.

Illustrations: C. Gao (ed.) 1996 (Pl. 75, figs. 16–17).