Polyphlebium angustatum is a species of fern in the family Hymenophyllaceae. It is found in South America and on a number of Atlantic islands, including Tristan da Cunha. The genus Polyphlebium is accepted in the Pteridophyte Phylogeny Group classification of 2016 (PPG I), but not by other sources. , Plants of the World Online sank the genus into a broadly defined Trichomanes, treating this species as Trichomanes angustatum.