三角叶凸轴蕨 san jiao ye tu zhou jue

Plants 23-55 cm tall. Rhizomes short, ascending, including stipe bases with grayish white acicular hairs and few brown linear-lanceolate small scales. Fronds approximate; stipes 10-30 cm, stramineous, subglabrous above bases; laminae ovate-triangular, 13-30 × 10-16 cm, broadest at bases, pinnate-pinnatifid, long acuminate and pinnatifid at apices; pinnae 10-14 pairs, spreading, proximal ones subopposite, distal ones alternate, proximal pinnae largest, bent distally, linear-lanceolate, 5-9.5 × 1.2-2.2 cm, bases truncate, sessile, pinnatifid and reaching narrow wings on both sides of costae, apices long acuminate; segments 12-20 pairs, 5-10 × 2-3 mm, entire, obtuse-pointed at apices. Veins evident abaxially, lateral veins simple or forked, 5 or 6 pairs per segment, not reaching margins. Laminae thinly herbaceous, when dry yellowish green, with grayish white short acicular hairs on both surfaces, hairs along rachises and costae denser. Sori small, orbicular, attached near ends of lateral veins, close to margins; indusia small, orbicular-reniform, thinly membranous, green, when dry grayish brown, with dense acicular hairs, persistent.

● Rock crevices at streamsides, streamsides in bamboo forests; 600-2200 m. Hunan, Yunnan.

The FRPS account of Metathelypteris misidentified material of M. deltoideofrons as M. decipiens (C. B. Clarke) Ching. Here, we follow Fraser-Jenkins (Taxon. Revis. Indian Subcontinental Pteridophytes, 592. 2008) and treat the latter as a synonym of species no. 11, M. flaccida.