Byrsopteris C. V. Morton; Leptorumohra (H. Itô) H. Itô; Lithostegia Ching; Phanerophlebiopsis Ching; Rumohra sect. Leptorumohra H. Itô.

Plants terrestrial, evergreen, medium-sized (or large). Rhizome long creeping to short and ascending, or rarely erect, densely scaly; scales filiform, subulate, lanceolate, or ovate, often attenuate toward apex, margin entire or with toothlike (rarely fimbriate) projections. Fronds few, remote or approximate; stipe equal in length to lamina or longer, base as densely scaly as rhizome, adaxially sulcate; lamina deltoid, ovate, pentagonal, or rarely lanceolate, usually 2-4(or 5)-pinnate, but simply pinnate in a few species, herbaceous, papery to leathery, glabrous or with a few narrow scales, rarely hairy; dissection anadromous throughout; rachis adaxially sulcate, grooves continuous with those on axes of higher order, scaly to glabrescent, or rarely with pale gray unicellular acicular hairs, scales entire (or with irregular projections on margin), sometimes with enlarged and denticulate base; pinnae a few to numerous pairs, usually shortly stalked, basal ones often with long basal basiscopic pinnules; upper divisions gradually reduced and ending in acuminate or caudate apices, or with a distinct terminal pinna; basiscopic pinnules often slightly longer than acroscopic ones; ultimate segments sessile, usually oblong to rhomboid, or rarely linear, often inequilateral, with an acroscopic auricle, margin sharply dentate to aristate; venation usually also anadromous, veins free, pinnate or forked, not quite reaching margin of ultimate segment, often ending in a hydathode. Sori orbicular, terminal or dorsal on acroscopic branches of veinlets; indusia orbicular-reniform, attached at a deep sinus, persistent or fugacious; sporangia numerous, long stalked, with an annulus of 13-16 thickened cells. Spores ellipsoid, often with broad rugate perispore. x = 41.

The following taxon is excluded from the present treatment, pending further research: Arachniodes heyuanensis Ching (Bull. Bot. Res., Harbin 6(3): 9. 1986), described from Guangdong.

About 60 species: tropical and subtropical regions worldwide, but mainly in E and SE Asia; 40 species (18 endemic) in China.

(Authors: He Hai (何海), Wu Sugong (武素功), Xiang Jianying (向建英); David S. Barrington)