Hymenophyllum Sm.

Involucre bivalvate (deeply or to the base) or bivalvate in the upper portion but obconic at the base Hymenophyllum
Margin of the lamina and the axes not clothed with branched hairs
Margin of the lamina entire
Lamina simple, once or rarely thrice forked. Involucre and/or the lamina with a black thickened margin Tiny mat-forming ferns. Rhizome wiry, sparsely clothed with a few undivided hairs. Stipes 0.3–7 mm long, filiform. Lamina simple, once or more rarely twice forked, thin, light green, linear to narrowly oblong, 4–35 mm long, 1–2.5 mm broad, glabrous; margins entire, glabrous, composed of 1–2 rows of black cells. Midrib black, glossy, without any lateral branchlets, clothed with a few, reddish, tubular hairs. Sori solitary at the apex of the frond or its lobes. Involucre oval or orbicular, 2-valved to the base, 0.8–1.5 mm long, light green, with a glossy black border 2–3 cells in width. Spores tetrahedral-globose or globose. Widespread but uncommon. RF, often near waterfalls, on rocks, logs or wet cliff-faces Hymenophyllum marginatum
Lamina pinnately divided. Involucre and lamina without a black thickened margin