4. Cyrto-hypnum gratum (P. Beauv.) Buck & Crum 密毛细羽藓 mi-mao xi-yu xian
Contr. Univ. Michigan Herb. 17: 65. 1990. Thuidium gratum (P. Beauv.) Jaeg., Ber. Thätigk. St. Gallischen Naturwiss. Ges. 1876–77: 256. 1878. Hypnum gratum P. Beauv., Prodr. Aethéogam. 64. 1805. Type. West Africa: Benin.
Cyrto-hypnum pelekinoides (P.-C. Chen) Buck & Crum, Contr. Univ. Michigan Herb. 17: 67. 1990. Thuidium pelekinoides P.-C. Chen, Sunyatsenia 6: 190. f. 23. 1941. Types. China: Hainan, Pepu (Bei-bo), C. Ho 1130b, 1131 (syntypes PE).
Plants delicate, medium-sized, up to 4 cm long, grayish green to yellowish green or dark green, becoming brownish when old, in small patches. Stems creeping, bipinnately branched; cortical cells 3–5 layers, central strand present; paraphyllia densely growing on stems and the base of branches, filamentous, rarely foliose, simple or branched, up to 8 cells long, apical cell truncate, pluripapillose. Stem leaves remote, suddenly narrowed from an ovate or triangular base to a lanceolate or narrowly lanceolate apex, 0.8–1.0 mm × ca. 0.6 mm; margins revolute or recurved, serrate or cellulose; costa single, consisting of 3–4 rows of narrow and thick-walled cells, papillose on back; leaf cells 7.5–10.0 µm, hexagonal to irregularly rectangular, with single acute or 2–4 fine papillae, walls equally thickened; branch leaves dense, appressed when dry, widely cordate to ovate-triangular, with a short, obtuse apex, rarely acute; marginal cells projected, round-toothed, finely papillose; costa reaching 2/3–4/5 the leaf length, papillose on back. Autoicous. Female inflorescences on stems, with 7–8 perichaetial leaves; inner perichaetial leaves oblong-ovate; costa broad, excurrent into a long awn; margins remotely crenulated, sometimes with 8–10 single celled, hyaline, cilia above. Setae ca. 1.0–1.5 cm long, lightly brownish, reddish when old, densely granulate; capsules ovoid to shortly cylindrical, ca. 0.5–1.2 mm long, horizontal or inclined; opercula 1 mm long; peristome teeth well developed, cilia 1–3, isolated or connected, sometimes rudimentary. Calyptrae cucullate, coarse at the apex. Spores 10–20 µm in diameter.