Plants large, terrestrial, glabrous throughout. Rhizomes long creeping, dark brown, woody, including stipe bases with dense dark brown lanceolate scales. Fronds remote; stipes strong, glabrous above bases, without tuberculate aerophores; laminae pinnate-pinnatifid; terminal pinna of similar shape and size as proximal lateral ones, stalked; segments pointed at apices, proximal 2.5 pairs forming sharp triangular elongate and translucent membranes at sinuses, connivent at or just below sinuses, keels protruding (arching) on abaxial laminar surfaces. Laminae firmly papery when dry, dark brown, subglabrous on both surfaces. Sori orbicular, exindusiate, not close to costules; sporangia glabrous.

Thelypteridaceae author Alan R. Smith prefers to follow Holttum and treat the one species of Mesopteris within Amphineuron (here subsumed within Cyclosorus). The present authors note that from the recent molecular phylogeny (He Lijuan, Molec. Phylogen. Evol., ined.) Mesopteris is not clustered together with Amphineuron species or other genera. While it is clearly a member of Cyclosorus s.l., it should be recognized as a separate genus, just as Glaphyropteridopsis and Pseudocyclosorus are here treated as separate genera.

One species: China, N Vietnam.

(Authors: Lin Youxing (林尤兴); Kunio Iwatsuki)