2. Onychium tenuifrons Ching, Lingnan Sci. J. 8: 500. 1934.
蚀盖金粉蕨 shi gai jin fen jue
Onychium japonicum (Thunberg) Kunze var. delavayi Christ.
Rhizomes short, decumbent; scales light brown, narrowly lanceolate. Fronds slightly dimorphic (fertile fronds with narrower segments than sterile ones), closely spaced, often appearing clustered. Stipe straw-colored, sometimes slightly darkened at very base, 7-20 cm × ca. 2 mm (longer on fertile than sterile fronds). Lamina of sterile fronds ovate to narrowly ovate or elliptic-lanceolate, 3-pinnate-pinnatifid, thinly herbaceous. Lamina of fertile fronds elliptic-lanceolate, 15-25 × 5-10 cm, 3- or 4-pinnate, apex acuminate, firmly papery when dry, green, not farinose; lateral pinnae 8-10 pairs; longest pinnae lanceolate, stalks 4-10 mm. Ultimate pinnules (segments) of sterile lamina crowded but mostly not overlapping, obovate or oblong, with sharp teeth at apex, 1 veinlet per tooth, margins often slightly thickened or somewhat cartilaginous. Ultimate pinnules (segments) of fertile lamina not overlapping, oblong-linear or lanceolate, 1-6 × 0.4-0.9 mm, sessile or decurrent on costule, apex acuminate or acute. Sori 3-5 mm, glabrous. False indusia linear to narrowly oblong, not approaching midvein, with erose margins. 2n = 87.
Forest margins, under shrubs; 100-2700 m. W Guizhou, Sichuan, Yunnan [Bhutan, India, N Myanmar, Nepal, Philippines].
Onychium tenuifrons is similar to O. japonicum but differs in having clustered fronds, lighter and thinner rhizome scales, and false indusia with erose margins.