1. Hydrogonium anceps (Card.) Herz. & Nog. 扁叶石灰藓 bian-ye shi-hui xian
J. Hattori Bot. Lab. 14: 60. 1955. Barbula anceps Card., Beih. Bot. Centralbl. 19(2): 102, f. 7. 1905. Type. China: Taiwan, Tai-pei Co., Kushaku 130 (holotype PC).
Plants medium-sized to rather large, 30–40 mm high, green to yellowish brown, in dense tufts. Stems erect, branched. Leaves erectopatent, flat, ovate-lanceolate, 2.0–2.3 mm × 0.6–0.8 mm, gradually acuminate at the apex; margins entire, weakly revolute; costa stout, percurrent; upper leaf cells quadrate or shortly rounded rectangular, thick-walled, minutely papillose; basal cells irregularly narrow-rectangular, thin-walled, smooth. Perichaetial leaves ovate-lanceolate, concave, gradually acuminate at the apex. Sporophytes not seen.