1. Ptychomitrium dentatum (Mitt.) Jaeg., Ber. Thätigk. St. Gallischen Naturwiss. Ges. 1872–73:102. 1874; Glyphomitirum dentatum Mitt., J. Proc. Linn. Soc., Bot. 8: 149. 1864.
Plants medium-sized, 2–3 cm high, green or yellowish green above, blackish green to black below, in loose tufts. Stems erect or ascending, sparsely branched; central strand well developed. Leaves 3.0–4.5 mm long, incurved when dry, spreading when moist, oblong-ovate to broadly lanceolate with an oblong, sometimes sheathing base, somewhat keeled above, broadly acute at the apex; margins plane, strongly toothed above, each tooth consisting of several cells; costa single, strong, ending just below the apex or subpercurrent; upper leaf cells often obscure, rounded-quadrate to subquadrate, 8–10 µm wide, slightly thick-walled; basal cells rectangular to short-rectangular, 26–39 µm x 8–10 µm, somewhat hyaline, thin-walled. Autoicous. Perichaetial leaves similar to upper stem leaves. Setae straight, yellowish brown, ca. 5.0 mm long; capsules erect, oblong-ellipsoid, ca. 2.0 mm long; peristome teeth reddish brown, linear-lanceolate, bifid nearly to the base, densely or finely papillose; annuli undifferentiated; opercula with short, erect beak. Calyptrae mitrate, reaching middle of capsule, longitudinally plicate, lobed at the base. Spores yellowish green, 10–14 µm in diameter, finely papillose.
Type. Japan: “Nagasaki, on rocks, oldham” (lectotype NY); China: “Sam-sa Bay, Alexander 20” (syntype NY).
Chinese specimens examined: FUJIAN: Nan-ping Co., C. Gao & Z.-W. Aur 25511 (IFSBH). HAINAN: Ling-shui Co., Reese 17928 (MO). QINGHAI: Xun-hua, J.-W. Zhang 5554 (PE). SHAANXI: Nan-wu-tai Shan (Mt.), C. Gao et al. 16570 (IFSBH). SICHUAN: Ba-kang Co., Allen et al. 6872 (MO); Kang-ding Co., S.-D. Zhao & Z.-F. Fang 1305 (IFSBH); Li Co., Allen et al. 6753 (MO); Mao-wen Co., Redfearn 35560a (as Ptychomitrium mariei, NY, SMS); Song-pan Co., Allen et al. 7159 (MO); between Wen-chuan Co. and Guan Co., Redfearn 35577 (as P. mariei, NY, SMS). YUNNAN: Lan-chang-jiang (River), D.-C. Zhang 1 (HKAS).
Habitat: on rocks or thin soil over rocks; Distribution: China, Korea, and Japan.
Ptychomitrium dentatum differs from P. wilsonii, by having oblong-ovate or broadly lanceolate leaves with narrowly oblong bases, relatively long, oblong-ellipsoid capsules, and bifid, linear-lanceolate peristome teeth.
Illustrations: Pl. 138, figs. 1–10.