Description from Flora of China
Adiantum acrocarpon Christ; A. nanum Ching.
Plants epilithic, small, 2-3 cm tall. Rhizomes erect, short, scales black-brown, lanceolate, margins entire. Fronds clustered; stipe dark castaneous, ca. 1 cm, as slender as silk; lamina 1-pinnate, ovate in outline, ca. 2 × 1 cm, costae and stalks same color as stipe; pinnules 1-3 pairs, subopposite, easily deciduous when dry; stalk 1-2 mm, articulate; blade obliquely spreading, orbicular or subovate-orbicular, 2.5-4 × 2.5-4 mm, papery, abaxially slightly pale blue-grayish, glabrous, adaxially brown-green and glossy, base rounded or rounded-cuneate, lateral margins entire or slightly undulate, upper margin rounded and with indistinct sinuses in middle; veins undivided, 4 forked veinlets running from base to margin, visible on both surfaces. Sori 1 per pinnule; false indusia brown, orbicular, upper margins flat and straight, slightly depressed, persistent.
● Usually gregarious on wet limestone cliffs; ca. 200 m. Guangxi, Guizhou, Hubei, Sichuan.