Tortrimosaica polypodivora Brown & Baixeras, new genus and new species, is described and illustrated from São Paulo, Brazil. We also describe and illustrate the last instar and pupa and provide notes on the life history. Larvae of the new species are gall inducers on the stems of Microgramma squamulosa (Kauf.) Sota (Polypodiaceae), an unusual behavior and host for a tortricid. Although placed provisionally in Hilarographini, tribal and subfamilial assignment of the new genus is extremely problematic owing to a mosaic of morphological characters, suggesting placement in a variety of different higher taxa. The larvae have a bisetose L-group on the prothorax, and the pupa has multiple rows of spines near the anterior edge of the dorsum of abdominal segments 3–8; both of these characters previously have been reported in the Tortricidae only in Thaumatographa (Hilarographini). Although the gall-inducing habit of the new species is not unique within Tortricidae, it is highly unusual within nonolethreutine lineages.