Genus Hymenophyllum Sm. (Smith 1793)

This pantropical genus (in addition to numerous species in wet temperate areas, especially in southern hemisphere) regroups more than 300 epiphytic (more rarely lithophytic), dwarf to large species with mostly long-creeping filiform rhizomes bearing sparsely distributed roots and pending dissected fronds in addition to sori without developed tubular base (at least for species of the region; Fig. 2A, F). In the Comoros, species belong to three subgenera following Ebihara et al. (2006): Hymenophyllum, Sphaerocionium (C.Presl) C.Chr. and Mecodium C.Presl ex Copel.