A late Cretaceous leaf miner, Leucopteropsa spiralae (Lepidoptera: Lyonetiidae), is the first fossil evidence of the Cemiostominae

A recently described fossil leaf mine ichnogenus and species, Leucopteropsa spiralae (Lepidoptera: Lyonetiidae), from the Upper Cretaceous Kaiparowits Formation in Utah, USA, is the earliest record (75.6 ± 0.18Ma) and singular fossil evidence of a lyonetiid-like leaf-mining moth, as well as one of the oldest known fossils within the Yponomeutoidea-Gracillarioidea clade. The blotch-style mine consists of a central oviposition site with a spiral trail packed with fecal pellets that concentrically spirals outwards. The morphology of the fossil mine is indicative of the subfamily Cemiostominae and is most similar to mines produced by extant members of the genus Leucoptera, such as the mountain ash bentwing moth, Leucoptera malifoliella. The leaf-mining moth responsible for L. spiralae may be an early member of the genus Leucoptera or other Cemiostominae genera. Despite our phylogenetic analysis of 15 lyonetiids, there is a need for further phylogenetic work within the Lepidoptera, in particular the placement of the family Lyonetiidae and the subfamily Cemiostominae within the larger Yponomeutoidea-Gracillarioidea phylogeny. This fossil discovery provides an important Late Cretaceous calibration point for lepidopteran phylogeny and serves as an indicator for the antiquity of the most diverse lepidopteran group, Ditrysia.