Plants small to medium-sized, pale glossy, whitish green, very compact, in dense turfs. Stems elongate, much-forked, rhizoids bright-red, sometimes conspicuous. Leaves straight and appressed wet and dry, 1.5–1.8 mm long, involute, lance-acuminate, composed mostly of cancellinae, with only small areas of green cells distally on both sides of costa, axillary hairs inconspicuous; green cells of upper laminae isodiametric, smooth abaxially, bulging to unipapillose adaxially; margins bordered all around with elongate hyaline cells, entire, more or less revolute distally along the green cells; cancellinae acute distally. Gemmae infrequent, inconspicuous, adaxial on tip of costa. Sporophytes frequent. Setae 5–7 mm long; capsules short-cylindric to somewhat urceolate, sulcate with age, 0.8–1.0 mm long, with few stomata at base; opercula long rostrate; peristome of low, blunt, imperfect teeth, to 60 µm tall, teeth narrowly segmented, irregularly patterned-papillose inside and outside in distal segments. Calyptrae 1.8 mm long, papillose-roughened distally. Spores green, 19–24 µm in diameter, finely papillose.

Type. Indonesia: “In insulae Rauwack Moluccensi,” Gaudichaud s.n. (holotype G; isotype BM).

Chinese specimens examined: HAINAN: Le-dong Co., P.-C. Chen 756a (IBSC, LAF, MO, PE).

Habitat: very rare; on tree trunks in forests at moderate elevations, 570 m; Distribution: very widespread in the Palaeotropics; China, India, throughout Malaysia, Australia, Oceania, and tropical Africa.

This species stands distinct from all other Chinese Syrrhopodon species in its peculiar leaves, in which there is only a small area of green cells toward the leaf apex, most of the leaf being composed of the large highly conspicuous cancellinae. Syrrhopodon involutus is common and often abundant in most of its distributed range, but it is rare in China. This species has been reported from China previously as S. borneensis (Hampe) Jaeg. and S. revolutus Dozy & Molk. (Lin & Reese 1988); both names were considered to be synonyms of S. involutus by Reese et al. (1986).

Illustrations: Reese & P.-J. Lin 1991 (figs. 82–88).