3. Taxiphyllum arcuatum (Bosch & Sande Lac.) S. He 钝头鳞叶藓 dun tou lin ye xian
J. Hattori Bot. Lab. 81: 37. 1997. Homalia arcuata Bosch & Sande Lac., Bryol. Jav. 2: 56. Pl. 176: B. 1862. Type: Indonesia. Moluccarum insula Halmaheira, Vriese s.n. (lectotype L); Sumatra Padang, Wilterns s.n. (syntype L).
Isopterygium subarcuatum (Broth.) Nog., J. Jap. Bot. 20: 148. 1944. Taxiphyllum subarcuatum (Broth.) Iwats., J. Hattori Bot. Lab. 26: 67. 1963. Homalia subarcuata Broth., Hedwigia 38: 229. 1899. Type: Japan. Kiushiu Nagasaki an Baumrinde, Wichura 1483a (holotype H).
Plants small, complanate, to 3 cm long; leafy stems 1–2 mm wide, glossy, yellowish green or pale yellow. Primary stems prostrate; secondary stems in soft, flattened mats, irregularly or subpinnately branched, branches short and patent, bifarious and complanate; pseudoparaphyllia filamentous, of 1–2(–3) rows of cells at base; rhizoids smooth, brownish; central strand absent, epidermis and cortex undifferentiated, outer cortex with 3–4 layers of small, thick-walled cells, inner cortex of larger, slightly thick-walled cells. Stem leaves and branch leaves similar, 0.65–1.15 mm × 0.30–0.50 mm, oblong-ligulate, often arcuate above, obtuse to rounded or obtusely pointed at apex; leaf margins faintly serrulate to crenulate above, entire or subentire below, often inflexed on one side at base; costae short, double or obsolete; leaf cells thin to moderately thick-walled, often prorate, apical leaf cells oblong-rhombic to rhomboidal, 12–17 µm × 5–7 µm, median leaf cells linear, 55–100 µm × 4.5–5.5 µm, basal juxtacostal cells oblong-linear, 25–45 µm × 5–7 µm, 1–2 rows of quadrate to oblong-quadrate cells at leaf base, alar cells not or slightly differentiated. Autoicous. Perigonia and perichaetia on secondary stems and branches, perigonial leaves smaller, ovate at base, abruptly narrowed to a short acumen; perichaetial leaves ovate and somewhat sheathing at base, gradually narrowed to a lanceolate acumen. Setae elongate, 8–10 mm long, yellowish; capsules oblong-ovoid to cylindrical, 1.0–1.3 mm × 0.6–0.7 mm in diameter, slightly asymmetric, suberect, sometimes horizontal or inclined; annuli well developed, with a layer of larger, fragmenting cells; opercula short rostrate from a conic base, 0.6–0.7 mm long; stomata superficial, at the neck of urns; peristome double, exostome teeth 16, lanceolate, 0.35–0.40 mm long, dorsal plates densely cross-striolate below, papillose above, distinctly wider than ventral plates throughout, the ventral plates smooth; endostome segments 16, lanceo-subulate, 0.30–0.35 mm long, keeled, perforate, clearly papillose; basal membrane 0.10–0.13 mm high, papillose; cilia 1–3, papillose, nodulose-appendiculate. Calyptrae cucullate. Spores 10–14 µm in diameter, faintly papillose.