15. Didymodon rivicolus (Broth.) Zand. in Kop., C. Gao, J.-S. Lou & Jarvinen, Annales Botanici Fennici. 20:222. 1983; Barbula rivicola Broth., Symb. Sin. 4: 41. 1929.
Didymodon mamillosus Dix. in C.-Y. Yang, Sci. Rep. Natl. Tsing Hua Univ., ser. B, Biol. Sci. 2: 116. 1936, nom. nud.
Plants medium-sized to rather large, to 40 mm high, yellowish green, in dense tufts. Stems erect, branched. Leaves appressed when dry, erect-spreading when moist, oblong-ovate, narrowly acute toward the apex; margins entire, revolute; costa stout, subpercurrent or ending just a few cells below the apex; upper leaf cells rounded quadrate to rounded hexagonal, thick-walled, each cell with a large papilla; basal cells irregularly rectangular, smooth, occasionally papillose. Perichaetial leaves inflated, sheathing at the base. Setae straight, ca. 1.5 cm long, reddish; capsules erect, cylindrical, yellowish brown; peristome teeth straight, linear lanceolate, irregularly divided to the middle, densely papillose; opercula conic-rostrate, with a short beak.
Type. China: Yunnan, Li-jiang, Handel-Mazzetti 6838 (holotype H).
Specimens examined: GANSU: He-lan Shan (Mt.), Z.-G. Tong 1353 (PE). GUIZHOU: Gui-yang City, B.-G. Zhong 117 (PE). HEBEI: C.-Y. Yang 271 (PE). JILIN: An-tu Co., Koponen 36732, 36902 (H). SHAANXI: Hu Co., M. Wang 532, 578 (HKAS). SICHUAN: Dao-cheng Co., M.-Z. Wang 814069 (PE); Lu-ding Co., Y. Xuan 17832 (HKAS); Wen-chuan Co., J.-X. Luo 3621 (PE); Xiang-cheng Co., X.-J. Li 81–2005 (HKAS); Yan-yuan Co., K.-K. Chen 527 (HKAS). XINJIANG: Urumqi Co., S. He 951082 (MO). XIZANG: Long-zi Co., M. Zang 1085, 1144 (HKAS); San-an Qu-lin, M. Zang 1366 (HKAS). YUNNAN: De-qin Co., M. Zang 8623 (HKAS); Jade Dragon Snow Mountain, Croat 77626 (MO); Kun-ming City, Croat 75962 (MO); Zhong-dian Co., J.-S. Yang 3821 (HKAS).
Habitat: on soil under bushes or in forests in alpine regions, or on rotten trees; Distribution: endemic to China.
Illustrations: Pl. 120, figs. 7–13.
