1. Tetrodontium brownianum (Dicks.) Schwaegr. 小四齿藓 xiao si-chi xian
Sp. Musc. Frond., Suppl. 2, 1(2): 102. 1824. Bryum brownianum Dicks., Fasc. Pl. Crypt. Brit. 4: 7. pl. 10, f. 16. 1801. Type. England: near Edinburgh, Brown s.n.
Plants minute, budlike, dark green or brownish, gregarious or in scattered tufts. Stems erect, simple, ca. 1.5–2.0 mm long, with few scale-like leaves. Leaves erect, narrowly ovate to oblong-ovate, somewhat concave, bluntly acute at apex; margins entire or irregularly serrulate near the apex; costa very slender, ending well below the apex; upper and median leaf cells irregularly rhomboidal or irregularly hexagonal, firm-walled, smooth; lower cells narrowly rectangular. Protonematal flaps present, numerous, often forming large patches on the rock surface. Autoicous. Setae elongate, straight or slightly curved, 7–15 mm long, smooth; capsules shortly cylindrical, 1.6–2.0 mm × 0.4–0.5 mm; opercula low-conic, 0.5–0.6 mm high; annuli absent; peristome teeth narrowly triangular, 0.4–0.5 mm long. Calyptrae long-conic, 2–3 mm long, deeply split, yellowish brown. Spores 10–12 µm in diameter, green, smooth.