4. Eurhynchium eustegium (Besch.) Dixon 尖叶美喙藓 jian ye mei hui xian
J. Bot. 75: 126. 1937. Eurhynchiadelphus eustegia (Besch.) Ignatov & Huttunen, Arctoa 11: 264. 2002[2003]. Brachythecium eustegium Besch., Ann. Sci. Nat., Bot., ser. 7, 17: 375. 1893. Type: Japan. Honshu, Pref. Aomori, Faurie 14.
Eurhynchium sinanense (Sakurai) Sakurai, Muscol. Jap. 142. 1954, nom. illeg. Rhynchostegium sinanense Sakurai, Bot. Mag. (Tokyo) 50: 621. 1936.
Plants large, yellowish green, dark green when old, slightly glossy, in loose mats. Stems prostrate, to 5–10 cm long, irregularly branched, densely foliate, with branches curved, attenuate at tips. Stem leaves sparse, oblong-ovate-lanceolate, 1.53–1.80 mm × 0.6–0.8 mm, long acuminate toward apex; margins serrulate throughout, incurved at base; costae ending ca. 2/3 the leaf length, projecting at tips; median leaf cells linear-rhomboidal to linear, 60–97 µm × 5–6 µm, thin-walled; alar cells quadrate to shortly rectangular; branch leaves narrowly ovate-lanceolate, 1.08–1.23 mm × 0.47–0.63 mm, somewhat plicate, shortly acuminate at apex, constricted at base. Dioicous? Perichaetial leaves lanceolate, ecostate. Setae 8–12 mm long, smooth; capsules inclined, ellipsoidal, necks developed; opercula long-rostrate; endostome segments shorter than exostome teeth. Spores not seen.