Abacopteris nudata

Abacopteris nudata is a fern species in the family Thelypteridaceae, with the specific epithet nudata derived from the Latin nudatus meaning naked or bare, likely indicating that this species produces fronds or sori that are distinctly lacking in indusia (the protective flaps covering the sori) or that the fronds are notably devoid of the hairs and scales typical of many Thelypteridaceae species. The absence or reduction of indusia is taxonomically significant within Thelypteridaceae, as indusium presence and morphology are key diagnostic features distinguishing genera and species within the family. Abacopteris nudata grows as a terrestrial fern in humid tropical and subtropical forests, producing fronds from a rhizome that creeps along the surface of moist, organic forest soils. The fronds are pinnate to bipinnate in structure, with a blade divided into lance-shaped pinnae bearing lobed margins and visible venation on their lower surfaces. The sori are arranged in rows along the veins on the lower pinnule surfaces, and in this species they may be exposed or exindusiate, consistent with the implication of the epithet. The stipe and rachis may be smooth to only slightly scaly or hairy, in keeping with the general bare appearance suggested by the name. Like all ferns, Abacopteris nudata reproduces via spores, undergoing an alternation of generations with a free-living prothallus gametophyte that is fertilized in moist conditions. The species is likely distributed in the humid tropics of Asia or Africa, where it grows in the shaded understory of lowland to lower montane forest.