Themelium tenuisectum (Blume) Parris
Themelium tenuisectum (Blume) Parris, Kew Bull. 52: 740. 1997; Parris, Fl. Pen. Malaysia, Ser. I, Ferns & Lycoph. 1: 194. 2010. – Polypodium tenuisectum Blume, Enum. Pl. Javae: 134. 1828. – Ctenopteris tenuisecta (Blume) J.Sm., Hist. Fil.: 185. 1875; Holttum, Rev. Fl. Malaya ed. 1, 2: 226, f. 123. 1955 [‘1954’]; Tagawa & K.Iwats., SouthE. Asian Stud. 5: 62. 1967; Tagawa & K.Iwats., Fl. Thailand 3: 590, f. 58.9–10. 1989; Boonkerd & Pollawatn, Pterid. Thailand: 241, 242, 291. 2000. – Type: Blume s.n., Java (holotype L).
Rhizome short creeping, about 2.5 mm diam., bearing closely spaced fronds, scaly; scales oblong-subtriangular, round to cordate at base, attenuate at apex, about 5 by 1.5 mm, entire at margin, brown. Stipes 0.9–3(–4.2) cm long, dark brown to castaneous, densely hirsute with setose, patent castaneous hairs up to 1.5 mm in length. Laminae narrowly ovate to elliptic, gradually narrowing downwards, acuminate at apex, 15–31 by 3–5.7 cm, deeply bipinnatifid to bipinnate; rachis narrowly winged, like stipes, densely hairy throughout; pinnae up to 64 pairs, narrowly oblong, 1.4–2.5(–3.3) cm by 4–6(–8) mm, the basal acroscopic lobes at junction between rachis and costa, the basal basiscopic lobes decurrent to rachis, lobed nearly to costa; lobes narrow, slightly falcate, oblique, 3 by 0.6 mm, rounded to moderately acute at apex, entire, each containing a veinlet; papyraceous. Sori one at base of each lobe, round , up to 1 mm diam.
Distribution in Thailand
PENINSULAR: Nakhon Si Thammarat.
Taiwan, Thailand, throughout Malesia (but not known in Sulawesi) to the Pacific Islands.
Epiphytic in dense evergreen forests at about 1500 m alt, on Khao Luang, known only on this mountain in Thailand.
Proposed IUCN Conservation Assessment
Least Concern (LC). This species is widespread outside of Thailand and not under any known threat. It is listed in the Flora of Peninsular Malaysia as Vulnerable.
Voucher specimens - Thailand
Van Beusekom & Phengkhlai 993, Nakhon Si Thammarat, Khao Luang (P).
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