1. Cyrto-hypnum bonianum (Besch.) Buck & Crum 纤枝细羽藓 qian-zhi xi-yu xian
Contr. Univ. Michigan Herb. 17: 65. 1990. Thuidium bonianum Besch., Bull. Soc. Bot. France 34: 98. 1887. Type. Vietnam: Ha-noi, Nam-cong, R. P. Bon 2413.
Thuidium lejeuneoides Nog., J. Jap. Bot. 13: 88. 1937. Type. China: Taiwan, Tai-pei Co., Urai, Suzuki 495.
Plants minute, yellowish green, dark green when old, in loose patches. Stems creeping, ca. 2–3 cm long, irregularly bipinnately branched; branches ca. 3 mm long; central strand undifferentiated; paraphyllia densely growing on stems, filiform, 3–6 cells long, rarely branched, papillose, truncate or rarely acute at apex; pseudoparaphyllia lanceolate or foliose, margins papillose, often present at the base of branches. Stem leaves slightly concave, appressed when dry, erect-spreading when moist, oblong-ovate at base, suddenly narrowed to a shortly lanceolate apex, ca. 0.3–0.4 mm long; margins serrate; costa vanishing at 3/4 the leaf length, minutely papillose at the back; median leaf cells hexagonal or rounded hexagonal, ca. 5–15 µm long, thin-walled, with a single, small papilla; apical leaf cells oblong or hexagonal, smooth; branch leaves concave, imbricate, usually ovate, with a short apex, arranged in two ranks. Autoicous. Inner perichaetial leaves with several flexuous cilia above, irregularly serrate along lower margins. Setae very slender, reddish brown, ca. 1 cm long, densely papillose; exothecial cells inconspicuously mammillose; peristome similar to that of Cyrto-hypnum pygmaeum (Schimp.) Buck & Crum; cilia 1. Spores smooth.