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.