Hymenophyllum denticulatum Sw.
Hymenophyllum denticulatum Sw., Schrad. J. Bot. 1800(2): 100. 1801; Bedd., Handb. Ferns Brit. India: 34. 1883; Copel., Philipp. J. Sci. 64: 41, pl. 15. 1937; Tardieu & C.Chr., Fl. Indo-Chine 7(2): 57. 1939; Holttum, Rev Fl. Malaya ed. 1, 2: 79. 1955 [‘1954’]; Tagawa & K.Iwats., Fl. Thailand 3: 612. 1989; Boonkerd & Pollawatn, Pterid. Thailand: 73. 2000. – Meringium denticulatum (Sw.) Copel., Philipp. J. Sci. 67: 42. 1938; Ching, Fl. Reipubl. Popularis Sin. 2: 150. 1959; Tagawa & K.Iwats., SouthE. Asian Stud. 5: 37. 1967; Tagawa & K.Iwats., Acta Phytotax. Geobot. 23: 51. 1968; Tagawa & K.Iwats., Fl. Thailand 3: 77. 1979.
Rhizome slender, bearing stiff, brownish hairs. Stipes narrowly winged almost to the base, hairy when young, 1–3 cm long. Laminae bipinnate to tripinnatifid, oblong-lanceolate to oblong-subdeltoid, acute at apex, narrowly cuneate (usually in larger fronds) to subtruncate (in smaller ones) at base, 3–8 cm long, 2–3 cm wide; pinnae oblong-ovate to lanceolate, round at apex, unequally cuneate at base, usually with less than 10 segments; ultimate segments linear-oblong, round to obtuse at apex, sharply toothed at margin, decurrent at base to form wings of axes, to 5 mm long, 1.3 mm broad; the wings of rachis and costae (sometimes the ultimate segments also) toothed and crisped to varying degree; cell walls rather thick, coarsely pitted. Sori apical on short acroscopic segments, usually near rachis in the upper part of fronds; involucre obconic, tubular with bilabiate mouth, with accessory wings, the lips round to moderately acute, serrate at margin .
Distribution in Thailand
PENINSULAR: Ranong, Nakhon Si Thammarat, Yala, Narathiwat.
Sri Lanka and N India through Malesia to Fiji, north to the Ryukyus.
On mossy tree trunks in dense tropical evergreen forest.
Hymenophyllum acanthoides (Bosch) Rosenst.
Proposed IUCN Conservation Assessment
Least Concern (LC). This species is common and widespread and not under any immediate known threat.
Voucher specimens - Thailand
Middleton et al. 3650, Yala, Hala-Bala Wildlife Sanctuary (E).
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