Abstract
Müllerian mimicry is a positive interspecific interaction, whereby co-occurring defended prey species share a common aposematic signal that advertises their defences to predators. In Lepidoptera, aposematic species typically harbour conspicuous opaque wing colour pattern, which have convergent optical properties, as perceived by predators. Surprisingly, some aposematic mimetic species have partially or totally transparent wings, which raises the question of whether optical properties of such transparent areas are also under selection for convergence. To answer this question and to investigate how transparency is achieved in the first place, we conducted a comparative study of optics and structures of transparent wings in neotropical mimetic clearwing Lepidoptera. We quantified transparency by spectrophotometry and characterised clearwing microstructures and nanostructures by microscopy imaging. We show that transparency is convergent among co-mimics in the eyes of predators, despite a large diversity of underlying micro-and nanostructures. Notably, we reveal that nanostructure density