2. Tetraphis pellucida Hedw. 四齿藓 si-chi xian
Sp. Musc. Frond. 43. pl. 7, f. 1: a–f. 1801. Georgia pellucida (Hedw.) Rabenh., Deutschl. Krypt.-Fl. 2(3): 231. 1848. Type. Europe.
Tetraphis cuspidata (Kindb.) Par., Index Bryol. Suppl. 318. 1900. Georgia cuspidata Kindb., Rev. Bryol. 20: 93. 1893.
Plants small to medium-sized, 10–18(–23) mm high, green above, rusty-brownish below, in solitary dense tufts. Stems erect, simple, often leafless below. Leaves small, ovate, distant on lower stem, larger and crowded on upper stems, appressed when dry, erect-spreading when moist, ovate to oblong-ovate, 1.5–2.2 mm × 0.5–1.0 mm, acute to acuminate at apex; margins entire, plane or broadly reflexed; costa thick, ending somewhat below leaf apex to subpercurrent, convex on the back; upper and median leaf cells irregularly rounded-hexagonal, ca. 12–16 µm wide, incrassate at corners, smooth; lower cells elongate, irregularly rectangular. Autoicous. Perichaetial leaves lanceolate, longer than stem leaves. Setae ca. 10–16 mm long, straight, somewhat twisted when dry, smooth; capsules narrowly cylindrical, ca. 3–4 mm × 0.4–0.5 mm, erect or sometimes slightly curved, symmetric, thickened at mouth; opercula long-conic, ca. 1 mm long; annuli absent; peristome teeth brownish, narrowly triangular, ca. 0.6–0.8 mm long. Calyptrae brownish, ca. 2.0–2.5 mm long, roughened above, smooth below, plicate, lobed at base. Spores ca. 10–12 µm in diameter, smooth.