14. Plagiothecium shevockii S. He 石氏棉藓 shi shi mian xian
Novon 18: 344. 2008. Type: China. Taiwan: Miaoli Co., Shei-Pa Nat. Park, on metamorphic rock underhang, 3600 m, 26 Apr. 1999, Shevock 18109 (holotype MO; isotypes CAS, PE, TAIE, UC).
Plants medium-sized, soft, yellowish green, glossy, in loose mats. Main stems prostrate, to 30 mm long, 4–6 mm wide when wet, secondary stems prostrate or slightly ascending, mostly simple, sometimes shortly branched, with strongly contorted leaves when dry; in cross section outermost layer of stem cells large, thin-walled, central strand weakly differentiated. Stem and branch leaves similar, contorted when dry, distantly spaced, spreading, symmetric, broadly ovate to orbicular at base, 2.8–3.1 mm × 1.8–1.9 mm, abruptly narrowed to a slenderly acute apex; margins plane, often dentate at apex; costae double or forked, ca. 1/3 to 1/2 the leaf length, occasionally appearing single; median leaf cells elongate-rhomboidal, 90–125 µm × 15–18 µm, thin-walled, smooth; apical cells significantly shorter than adjacent cells, 20–30 µm × 12–14 µm, thin-walled, hyaline, often bearing rhizoids on the abaxial surface; basal juxtacostal cells shorter and broader than median cells; alar regions markedly differentiated, with somewhat enlarged, thin-walled, rectangular cells, strongly decurrent with long, narrow stripes along stem in 2–4 rows and 12 cells long. Dioicous? Perichaetial leaves shortly ovate-lanceolate. Sporophytes not seen.