Syngramma minima Holttum
Pteridaceae, subfamily Pteridoideae
Syngramma minima Holttum, Gard. Bull. Straits Settlem. 4: 56. 1927; Holttum, Rev. Fl. Malaya 2: 585, fig. 345. 1955 ['1954']; Wai et al., Thai For. Bull. (Bot.) 39: 28. 2012 ['2011']. – Type: Peninsular Malaysia, Gunong Panti, 14 Feb. 1926, Holttum [SFN] 17498 (Lectotype : BM (Barcode: BM000066405); isolectotypes: BM (Barcode: BM000066788), K, SING, US).
Lithophyte (but also recorded, possibly mistakenly, as terrestrial). Rhizome short, creeping, 1.5-3 mm diam. when fresh, 1-1.5 mm diam. when dry, bearing crowded fronds, densely covered with bristles; bristles stiff, multicellular, 0.5-1.5 mm long, dark brown but slightly translucent and very shiny. Fronds monomorphic, simple. Stipes not articulate to rhizome, 1-3 cm long, narrowly and shallowly grooved above, very narrowly winged, green or sometimes purplish brown, densely covered with bristles (like those on the rhizome) at the base. Laminae coriaceous, rigid, narrowly oblong to linear-oblong or spatulate, 2-11 by 0.35-1 cm, olive green, glabrous, apex rounded, base attenuate, margin cartilaginous, lateral margins varying from almost entire to strongly denticulate, apical margin always crenate or denticulate; midrib slightly raised above, strongly raised below, narrowly and shallowly grooved above when fresh but grooves indistinct when dry, green or sometimes purplish brown; veins simple or once forked, all (except sometimes the most basal ones) joining an intramarginal vein, slightly raised on the upper surface, sometimes inconspicuous especially in old fronds. Fertile fronds soriferous for their entire length. Sori exindusiate, linear along the veins, extending from about half way to near the apical part of veins, 0.5-2 mm long; soral paraphyses present and conspicuous, terminal cells enlarged, reddish brown or red, translucent and shiny; sporangia subsessile (but at lower magnifications appearing sessile), 0.15- 0.2 mm diam., glabrous; annulus vertical, interrupted by the sporangial stalk. Spores trilete, tetrahedral, subglobular, 35-40 µm diam., rough, irregularly tuberculate , pale yellow.
Distribution in Thailand
PENINSULAR: Yala, Narathiwat.
Wai 984 was collected on cliffs in shady areas near the top of quartzitic phyllite ridges at an altitude of 650 m. Niyomdham 4845 is reported to have been terrestrial at 665 m but with no other habitat information. The type material (Holttum [SFN] 17498) was found growing among liverworts on a vertical rock face at approximately 488 m ("1600 ft") but the precise nature of this rock is uncertain, having been described first as "sandstone" (Holttum, 1927) then later as "quartzite" (Holttum, 1955).
Proposed IUCN Conservation Assessment
Data Deficient (DD). The species is known from very few collections which are quite widely separated and its precise distribution is unclear. The few collections suggest it is rarely encountered but the lack of good distribution data leaves us to conclude it must be given a DD status.
Until its discovery in Thailand Syngramma minima Holttum was known only from the type locality in Peninsular Malaysia.
Voucher specimens - Thailand
Wai 984, Yala, Betong (PSU); Niyomdham 4845, Narathiwat (BKF).
Upper surface of lamina
Lower surface of lamina with sori
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