Based on a collection from north-central Peru, a new tuberous species of Polypodiaceae is recognized and described as Microgramma fosteri. It differs from other coenosoric species by the presence of laminar scales intermixed among the sori and slender paraphyses with elongate apical cells possessing clear lumina and thin walls. A key for species identification in subgenus Solanopteris, to which the new species belongs, is provided. In addition, a new combination is made for a species previously recognized in the genus Solanopteris.