Plants small, 1–2 cm high, compact, yellowish green, in low dense sods or loosely gregarious. Stems evident, forked, rhizoids inconspicuous, glossy dark red. Leaves mostly ascending-flexuous when dry, ascending and often folded-falcate when wet, linear-acuminate above slightly broader base, mostly 3 mm long, upper laminae only 2 times length of lower, axillary hairs inconspicuous; cells of upper laminae pellucid, isodiametric, finely pluripapillose to bulging-pluripapillose abaxially, bulging-pluripapillose with tall divided papillae adaxially; margins of upper laminae bordered all around with elongate hyaline cells, entire except often toothed at apex and sometimes also at shoulders, teeth at shoulders mostly small, sharp, inconspicuous, rarely large and even cilia-like; cancellinae rounded to acute distally. Gemmae usually inconspicuous, adaxial on tip of costa. Sporophytes not seen.

Type. Japan: Tosa, J. M. Holzinger s.n. (isotype FH).

Chinese specimens examined: FUJIAN: Zhang-zhon-shi Shan (Mt.), Zang & Qin 383 (IBSC, KUN, LAF). GUANGDONG: Zhao-qing Co., P.-J. Lin & Z.-H. Li 71 (IBSC, LAF, SYS). GUANGXI: Long-sheng Co., P.-C. Wu et al. 1326 (IBSC, LAF, PE); Shang-si Co., P.-J. Lin et al. 2191 (IBSC, IFP, LAF); Xing-an Co., P.-J. Lin et al. 1200 (IBSC, IFP, LAF). HAINAN: Chang-jiang Co., Reese et al. 17613 (IBSC, LAF, MO); Le-dong Co., P.-C. Wu et al. 85191 (IBSC, H, LAF, PE, SYS), Reese 17747 (LAF, MO); Ling-shui Co., Reese et al. 17896 (IBSC, LAF, MO). HONG KONG: Da-Mo Shan (Mt.), P.-J. Lin et al. 313 (IBSC).

Habitat: common and often abundant on tree trunks and bases, soil, rock, humus, stumps, decaying logs in often more or less open forests at low to rather high elevations, 250–1300 m; Distribution: China and Japan.

This moss is weedy in parts of its range in China. It is readily recognized by its small size, bordered acuminate leaves, and pellucid, bulging-pluripapillose cells of the upper laminae. Most of the specimens have the margins entire at the leaf shoulders, but many collections include plants with some well-developed teeth at the shoulders. Similar taxa include S. prolifer var. prolifer and S. hainanensis (see comments in discussion under those names). Some of the Chinese specimens that we have classified under this name are similar to S. prolifer var. albidus (Thwaites & Mitt.) Orbán & Reese, but we were not able to apply the latter name with certainty to any of the collections we examined. The var. albidus differs from var. tosaensis in lacking teeth on the leaf shoulders and having generally larger leaf cells. See Orbán and Reese (1990) for a review of the S. prolifer complex.

Illustrations: Pl. 99, figs. 1–7.