1. Arctoa fulvella (Dicks.) Bruch & Schimp. in B.S.G. 极地藓 ji-di xian
Bryol. Eur. 1: 156. (fasc. 33/36 Mon. 4, 1). 1846. Bryum fulvellum Dicks., Pl. Crypt. Brit. Fasc. 4: 10. 1801. Type. Scotland.
Plants small, 1–2(–3) cm high, yellowish green, brown or black, in dense tufts. Stems simple or forked, radiculose at base. Leaves 2–3(–4) mm long, erect-patent or somewhat secund, from a lanceolate base narrowed to a long, roughed, slender subula; margins entire or serrulate at the apex; costa slender, ca. 1/5 the leaf base width, filling most of the subula and long excurrent; upper cells rectangular to oblong-rectangular, 2–5:1; lower cells becoming longer; alar cells differentiated, quadrate, brownish to yellowish brown. Perigonia relatively large, terminal on very short branches, or sessile, somewhat below the perichaetia. Perichaetial leaves up to 5 mm long, sheathing at the base. Setae 2–5 mm long, yellowish, thick; capsules erect, shortly obovoid, slightly asymmetric; annuli in 2–3 rows of cells, persistent; opercula stoutly short-rostrate; peristome teeth reddish brown, wide-spreading when dry, irregularly divided halfway down or less, sometimes undivided and perforate near the middle, vertically striate near to the tips. Spores green, spherical, 14–20(–24) µm in diameter, finely papillose.