Unveiling Shortfalls in Biodiversity Knowledge of Brazilian Butterflies

Three biodiversity knowledge gaps, known as the Linnaean, Wallacean, and Darwinian shortfalls, limit our ability to model biodiversity, assess extinction risk, and understand evolutionary patterns. These shortfalls are particularly severe for insects, which remain comparatively overlooked in science and conservation relative to plants and vertebrates. Here, we investigated the patterns of these knowledge gaps for 3567 Brazilian butterfly species. Our models suggest that Brazilian butterfly diversity may reach approximately 4200 species, indicating that more than 600 species likely remain undescribed and that, at current description rates, documenting this diversity could take several decades. Spatial analyses showed high bias in occurrence records, with large portions of the country lacking occurrence records and most sampled communities with low sampling completeness. Model predictions revealed high estimated richness in the south-eastern Atlantic Forest, western Amazon Rainforest, and parts of the Cerrado. In addition, more than half of all species lack publicly available genetic data, potentially limiting their inclusion in phylogenetic studies. Our results reveal that substantial knowledge gaps persist even for one of the most intensively studied insect groups and highlight key priorities for future taxonomic, sampling, and molecular efforts aimed at improving our understanding and conservation of Brazilian butterfly diversity.