PT - JOURNAL ARTICLE AU - Aaron F. Pomerantz AU - Radwanul H. Siddique AU - Elizabeth I. Cash AU - Yuriko Kishi AU - Charline Pinna AU - Kasia Hammar AU - Doris Gomez AU - Marianne Elias AU - Nipam H. Patel TI - Developmental, cellular, and biochemical basis of transparency in the glasswing butterfly <em>Greta oto</em> AID - 10.1101/2020.07.02.183590 DP - 2020 Jan 01 TA - bioRxiv PG - 2020.07.02.183590 4099 - http://biorxiv.org/content/early/2020/07/06/2020.07.02.183590.short 4100 - http://biorxiv.org/content/early/2020/07/06/2020.07.02.183590.full AB - Numerous species of Lepidoptera have transparent wings, which often possess scales of altered morphology and reduced size, and the presence of membrane surface nanostructures that dramatically reduce reflection. Optical properties and anti-reflective nanostructures have been characterized for several ‘clearwing’ Lepidoptera, but the developmental basis of wing transparency is unknown. We apply confocal and electron microscopy to create a developmental time-series in the glasswing butterfly, Greta oto, comparing transparent and non-transparent wing regions. We find that scale precursor cell density is reduced in transparent regions, and cytoskeletal organization differs between flat scales in opaque regions, and thin, bristle-like scales in transparent regions. We also reveal that sub-wavelength nanopillars on the wing membrane are wax-based, derive from wing epithelial cells and their associated microvillar projections, and demonstrate their role in enhancing-anti-reflective properties. These findings provide insight into morphogenesis of naturally organized micro- and nanostructures and may provide bioinspiration for new anti-reflective materials.Competing Interest StatementThe authors have declared no competing interest.