— Morphological studies and molecular phylogenetic analyses were carried out to examine the taxonomic position of Hymenophyllum caudiculatum , a species with disjunct distributions in South America. This species is found in tropical and subtropical forest of Brazil and in temperate forest of southern Argentina and Chile. Based on results obtained from morphological, molecular, and species delimitation analyses, Hymenophyllum caudatum , from the Valdivian forest of southern Chile and Argentina, is proposed as a species separate from H. caudiculatum , endemic of Brazil. Their diagnostic characters are respectively: nonalate stipe 1–5 cm long (vs. nonalate stipe 0.3–1 cm long in H. cuadiculatum ); stipe wings gradually ending (vs. stipe wings abruptly ending very near to the rhizome); margin entire to somewhat undulate (vs. margin undulate to crispate); soriferous segment alate, angostate or null (vs. soriferous segment with laminar constriction in the apex); widely obovoid receptacle with sessile sporangia (vs. flattened obovoid or globose receptacle with shortly pedunculated sporangia). A key to identify both species herein recognized, and a map containing geographical distribution of them are provided, together with nomenclatural revision, description, illustration and conservation status of the two recognized species.