Pyrrosia porosa (C.Presl) Hovenkamp var. tonkinensis (Giesenh.) Hovenkamp
Pyrrosia porosa (C.Presl) Hovenkamp var. tonkinensis (Giesenh.) Hovenkamp, Blumea 30: 208. 1984; Hovenkamp, Leiden Bot. Ser. 9: 29. 1986. – Niphobolus tonkinensis Giesenh., Nipholobus: 144. 1901. – Pyrrosia tonkinensis (Giesenh.) Ching, Bull. Chin. Bot. Soc. 1: 55. 1935; Tardieu & C.Chr. in Fl. Indo-Chine 7(2): 506. 1941; Tagawa & K.Iwats., SouthE. Asian Stud. 5: 48. 1967; Tagawa & K.Iwats., Fl. Thailand 3: 501, f. 50.6. 1989; Boonkerd & Pollawatn, Pterid. Thailand: 288. 2000; Newman et al., Checkl. Vasc. Pl. Lao PDR: 30. 2007.
Rhizome creeping, about 2 mm diam., bearing fronds rather closely spaced, densely scaly except in older portion; scales oblong-subulate, long-tailed at apex, up to 4 by 1 mm, dark brown to nearly black in central portion, brown in other parts, thin, ciliate to dentate. Fronds simple. Stipes not distinct with wings decurrent from laminae. Laminae linear, up to 30 cm long, commonly up to 7 mm but rarely up to 21 mm broad, gradually narrowing towards both apex and base; midrib grooved or planate on upper surface, raised beneath, glabrescent; fleshy, rather leathery, veins invisible, upper surface stellate hairy or glabrescent, lower surface covered with two kinds of hairs, the lower grey appressed hairs and the upper pale stellate hairs with short stalks. Sori on the whole lower surface of upper half of fronds, covered with stellate hairs when young.
Distribution in Thailand
NORTHERN: Mae Hong Son, Chiang Mai, Chiang Rai, Lamphun; NORTH-EASTERN: Loei; EASTERN: Chaiyaphum, Nakhon Ratchasima; SOUTH-WESTERN: Kanchanaburi.
Distribution in Laos
From India to Japan, Taiwan, Indochina and the Philippines.
On mossy tree trunks or on rocks usually in mountain forests at high altitudes (600–1600 m), rather rare.
Proposed IUCN Conservation Assessment
Least Concern (LC). This variety is widespread and not under any known threat.
Voucher specimens - Thailand
Middleton et al. 4959, Mae Hong Son, Ban Mae Yom Noi (E); Middleton et al. 5008 & 5009, Chiang Mai, Doi Chiang Dao Wildlife Sanctuary (E).
Rhizome and stipes
Upper surface of frond with hydathodes
Midrib on lower surface of frond
Lower surface of frond with sori
Lower surface of frond with mature sori
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