title: Variation in the circularly polarized light reflection of Lomaptera (Scarabaeidae) beetles.
abstract: An extended spectroscopic study on the left-through-left circularly polarized reflection spectra of a large number of beetles from the Australasian Scrabaeidae:Cetoniinae of the Lomaptera genus was undertaken. We have obtained a five-category spectral classification. The principal spectral features, which even within the genus range from blue to infrared, are related to structural chirality in the beetle shells. The detailed features of each spectral classification are related to different structural perturbations of the helix, including various pitch values and abrupt twist defects. These spectral characteristics and associated shell structures are confirmed on the basis of simple modelling. An important conclusion from our study is that the simple helical structure resulting in a single symmetric Bragg peak is not the dominant spectral type. Rather the reality is a rich tapestry of spectral types. One intriguing specimen is identified via a scanning electron micrograph to consist of a double interstitial helix leading to a particular double-peak spectrum.
authors.affiliation: The Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, UK ian.carter12@imperial.ac.uk.
authors.forename: I E
authors.initials: IE
authors.lastname: Carter
authors.affiliation: The Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, UK.
authors.forename: K
authors.initials: K
authors.lastname: Weir
authors.affiliation: The Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, UK.
authors.forename: M W
authors.initials: MW
authors.lastname: McCall
authors.affiliation: Department of Life Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, UK.
authors.forename: A R
authors.initials: AR
authors.lastname: Parker
mesh_terms: D000825:Animal Structures; D000818:Animals; D001517:Coleoptera; D008027:Light
keywords: birefringent; chiral; chitin; circular polarization; scarab beetle; structural colour