Family

Thelypteridaceae

Nomenclature

Cyclosorus evolutus (C.B.Clarke & Baker) Ching, Bull. Fan Mem. Inst. Biol. 8: 219. 1938. – Nephrodium amboinense var. evolutum C.B.Clarke & Baker, J. Linn. Soc. 24: 417. 1888. – Thelypteris evoluta (C.B.Clarke & Baker) Tagawa & K.Iwats., Acta Phytotax. Geobot. 22: 101. 1967; SouthE. Asian Stud. 5: 66. 1967; Tagawa & K.Iwats., Fl. Thailand 3: 430. 1988. – Christella evoluta (C.B.Clarke & Baker) Holttum in B.K.Nayar & S.Kaur, Companion Handb. Ferns Brit. India: 208. 1974; Holttum, Kew Bull. 31: 330. 1976; Boonkerd & Pollawatn, Pterid. Thailand: 220. 2000. – Lectotype (by Ching, 1938?): G.Mann, Assam, Khasya Hills, 1400 m (K).

Description

Rhizome short creeping; stipe 20–50 cm long, pale, hairy in groove only. Laminae once-pinnate, 47–112 cm long; pinnae widely spaced, to 15 pairs; lower 2–5 pairs gradually or abruptly reduced, strongly auricled, lowest 1.5 cm long. Largest pinnae 12–25 x 2.8–4 cm, not auricled, sessile, short-acuminate, lobed about 1/5 way towards costa; lobes slightly falcate, rounded but with a very short forward-pointing tip; costules 6–6.5 mm apart; veins 8–10 pairs, prominent, slender and pale, 2.5 pairs anastomosing, 1.5 pairs to sinus-membrane; lower surfaces throughout bearing minute hairs to glabrous verrucose; upper surface hairy only on rachis and costae. Sori medial, lower ones divergent; indusia bearing minute hairs as lamina .

Distribution in Thailand

NORTHERN: Chiang Rai, Tak; NORTH-EASTERN: Loei.

Wider Distribution

India (Assam).

Ecology

On humus-rich slopes in evergreen forests at medium altitudes.

Proposed IUCN Conservation Assessment

Least Concern (LC). This species is fairly widespread and not under any known threat.