Plants small, ca. 1 cm high, dark green distally, brownish proximally, in low often rust-colored sods or gregarious. Stems short; rhizoids dark glossy red. Leaves curled-involute and often secund when dry, involute and spreading when wet, ligulate to ligulate-acuminate above slightly broader base, 2–3 mm long; axillary hairs inconspicuous; cells of upper laminae isodiametric, pluripapillose abaxially, bulging pluripapillose adaxially; margins of upper laminae more or less involute, bordered with hyaline cells, border narrow, weak or lacking toward leaf apex, sometimes difficult to see due to involution of leaf margins, margins of lower laminae toothed to weakly ciliate at shoulders, the teeth often weak or more or less lacking; cancellinae rounded distally. Gemmae frequent, adaxial on costa tip. Sporophytes not seen.

Type. Singapore: Gaudichaud s.n. (isotypes BM, NY, S).

Chinese specimens examined: GUANGDONG: Zhao-qing Co., G.-L. Shi 11693 (NICH). HAINAN: Le-dong Co., P.-C. Chen et al. 128 (IBSC, LAF, PE); Ling-shui Co., Reese et al. 17848 (IBSC, LAF, MO). HONG KONG: Da Po Kau, P.-J. Lin et al. 1102; Mt. Kadoorie, P.-J. Lin et al. 83 (IBSC). TAIWAN: Nan-tou Co., C.-C. Chuang & Schofield 663 (UBC).

Habitat: very rare; on tree trunks and bases, decaying logs, in humid forests at 680–800 m; Distribution: China, Japan, Sri Lanka, Andamans, Malaysia, Australia, and western Oceania.

Syrrhopodon trachyphyllus, formerly known in China as S. semperi C. Müll. (a synonym), is easy to recognize by its small stature, brownish color, toothed-ciliate leaf shoulders, and pluripapillose leaf cells. In habit, habitat, and general aspect, S. trachyphyllus appears to be almost identical to S. armatus, from which it differs most obviously in having pluripapillose leaf cells, in contrast to the unipapillose cells of S. armatus. The two species are often confused. They sometimes grow together in the same habitat and on the same substrate, as in Chen et al. 262b, from Jianfengling Mt., Hainan Island (IBSC, LAF, PE). In such cases the two species cannot be told apart except under the microscope. Syrrhopodon hainanensis is also similar in a general way, but the plants are much larger, glaucous-green rather than rust-colored, and have large delicate cilia, among other differences.

Illustrations: Reese & P.-J. Lin 1991 (figs. 109–115).