2. Archidium yunnanense T. Arts & R. Magill 云南无轴藓 yun-nan wu-zhou xian
J. Bryol. 18: 63. 1994. Type. China: Yunnan, Xishuangbanna, Meng-la Co., at km marker 637 along Menglun-Mengbang road, north facing wooded slope, R. Magill, P. Redfearn & M. Crosby 7704, 22 December 1986 (holotype MO; isotypes KUN, PC).
Plants ca. 5 mm high, dull green, in small dense tufts. Stems erect, not or scarcely branched, ca. 0.10–0.15 mm in diameter, pale green, cells in cross section thin-walled throughout, medulla cells 20–25 mm in diameter, epidermal cell layer smaller, ca. 10–15 mm in diameter. Leaves densely placed around stems, erect-patent, long-triangular, 0.7–1.1 mm ´ 0.15–0.17 mm, gradually tapering from the base into a sharp angled apex; leaf margins smooth, plane; costa percurrent to shortly excurrent, 50–60 mm wide at the base, in cross section flattened, only 20–25 mm thick, stereids absent; leaf cells rather uniform, mid-leaf cells rectangular to hexagonal, ca. 40–60 mm ´ 7–9 mm, marginal cells not differentiated from the mid-leaf cells, basal cells shorter and wider, 15–35 mm ´ 12–15 mm. Rhizoids up to 50 mm wide, smooth, pale grayish brown; rhizoidal tubers present at the end of the main rhizoid branches, consisting of a uniseriate row of inflated cells, 0.5–2.0 mm ´ 100–200 mm; tuber cells isodiametric, subspherical. Sporophytes unknown. (Description of the species is mainly adopted from Arts & Magill 1994.)