纤细狗牙藓

Didymodon gracilescens (Web. & Mohr) Mitt., J. Linn. Soc. Bot. Suppl. 1: 23. 1859.

Plants slender, 1–3 cm high, bluish green to yellowish green, in compact tufts. Stems erect, simple or branched, radiculose below. Leaves 2.5–4.0 mm long, lanceolate, keeled, gradually tapered from a rather broad, somewhat sheathing base to narrowly acuminate apex; margins slightly involute here and there, serrulate from the middle; costa percurrent, papillose on the back nearly throughout to the base; upper cells oval-quadrate, highly long spinose on both surfaces; lower cells oblong-rectangular, 70–80 µm × 20–25 µm, hyaline and smooth, becoming shorter and narrower toward the margins; alar cells not differentiated. Autoicous. Perigonia sessile. Inner perichaetial leaves shorter and more strongly sheathing, oblong. Setae ca. 1 cm long, straight when dry, rather cygneous when moist, yellowish brown; capsules erect, narrowly ellipsoid, ca. 1.6 mm × 1.0 mm, not strumose, but nodding, deeply ribbed when dry; opercula long conic-rostrate; annuli developed, in 2 rows; peristome teeth reddish brown, short, divided about halfway down. Spores 14–18 µm in diameter, brownish.

Type. Germany.

Chinese specimens examined: HEILONGJIANG: Bei-an Co., C. Gao 13299 (IFSBH, MO); Xiao Xing An Ling (Lesser Khingan Mt.), Y. Wu & C. Gao 8175, 11728 (IFSBH, MO). HUBEI: Shen-nong-jia Distr., P.-C. Wu 257 (MO). JILIN: An-tu Co., C. Gao 966 (IFSBH); Changbai Shan (Mt.), C. Gao 7354 (IFSBH), 7651 (MO). SICHUAN: Liang Shan (Mt.), G.-C. Zhang 21374 (MO); Mu-li Co., C. Gao 20255 (IFSBH, MO); Nan-chuan Co., M.-Z. Wang 860944 (MO); Tian-quan Co., C. Gao 17878 (IFSBH, MO); Ya-jiang Co., S. He 31888b, 31954b (MO). XIZANG: Ya-dong Co., M. Zang 678c (KUN), S.-K. Chen 362 (KUN). YUNNAN: Li-jiang Co., W.-X. Xu 0181 (YUKU).

Habitat: on moist soil over rocks or humic soil, rarely on bases of trees; Distribution: China, Korea, Japan, Russia, Europe, and North America.

This species is characterized by having spinose leaf cells and rather cygneous setae.

Illustrations: C. Gao (ed.) 1994 (Pl. 93, figs. 1–6).