2. Calymperes erosum C. Müll., Linnaea. 21:182. 1848.
Calymperes fordii Besch., Ann. Sci. Nat. Bot., sér. 8, 1: 284. 1896. Type. China: Hong Kong (C. Ford, in herb. de Poli, no. 140) (isotypes FH–Fleischer, NY).
Plants blackish proximally, yellowish green distally, sometimes forked, in low dense turfs. Stems evident; rhizoids brown to glossy blackish red. Leaves essentially monomorphic, vegetative leaves grading into gemmiferous leaves, mostly little-contorted and appressed-secund when dry, bases conspicuous and with metallic hue, erect-spreading when wet, lanceolate to narrowly or broadly acuminate above broader base, to 4–5 mm long, axillary hairs inconspicuous; costa excurrent in gemmiferous leaves; median cells of upper laminae isodiametric, nearly smooth to sharply papillose abaxially, bulging to mammillose-papillose adaxially; margins more or less thickened and toothed distally; teniolae usually conspicuous; at least some (often most) distal cells of cancellinae distinctly mammillose, with mammillae pointing distally, adjacent green cells of upper laminae also mammillose. Gemmae common, in reddish spherical clusters borne all around on excurrent tip of costa. Sporophytes not seen.
Type. Suriname: Kegel s.n. (holotype GOET; isotype PC).
Chinese specimens examined: GUANGDONG: Zhao-qing Co., P.-J. Lin & Z.-H. Li 74 (IBSC, LAF, SYS). GUANGXI: Shang-si Co., P.-J. Lin et al. 1918 (IBSC, IFP, LAF). HAINAN: Chang-jiang Co., Redfearn et al. 35910 (IBSC, LAF, MO); Le-dong Co., P.-C. Chen et al. 740b (IBSC, LAF, PE); Ling-shui Co., Reese 17826 (IBSC, LAF, MO). HONG KONG: Victoria Peak, Iwatsuki et al. s.n. (HIRO, IBSC, LAF, NICH); Da-Mo Mt., P.-J. Lin et al. 308 (IBSC); Da-Po-Kau, P.-J. Lin et al. 1091 (IBSC).
Habitat: neither common nor abundant; at moderate elevations on tree trunks, rock, and rotted logs in forests, 70–1000 m; Distribution: pantropical.
Calymperes erosum is well marked by its reddish gemmae borne in a ball-like cluster all around on the tip of the excurrent costa and by the distinctive mammillose distal cells of its cancellinae. The latter alone will distinguish it easily even when gemmae are lacking, although then the excurrent costa from which gemmae have dehisced is still distinctive. The mammillose cells may be lacking at the very tips of the cancellinae but can be found along the sides of the cancellinae just proximal to their tips. The only other Chinese Calymperes with gemmae borne all around the tip of the excurrent costa is C. tenerum, which lacks teniolae and has plane distal cancellinae cells. The species most often confused with C. erosum is C. afzelii, but C. afzelii has the distal cells of its cancellinae plane and bears gemmae only on the adaxial surface of its costa tip, which is never excurrent. Some plants of C. erosum have the leaves all or mostly broad and nongemmiferous and may look very different from plants with the leaves all narrowly acuminate and gemmiferous. Calymperes erosum has previously been known in China under the name C. hampei Dozy & Molk., a synonym (cf. P.-J. Lin & Reese 1988).
Illustrations: Reese & P.-J. Lin 1991 (figs. 21–28).