Sexual Dichromatism of the Damselfly Calopteryx japonica Caused by a Melanin-Chitin Multilayer in the Male Wing Veins
Figure 5
Wing refractive index as a function of wavelength for the damselfly Calopteryx japonica and the Black-tailed Skimmer dragonfly, Orthetrum cancellatum.
A Real part of the refractive index, noR, of the wings derived from the Jamin-Lebedeff measurements (Figure 6B) for the mature male (MM), mature female (MF), immature male (IM) and the dragonfly (Oc) (symbols). The black curve represents the chitin dispersion function derived from the glass scale of the butterfly Graphium sarpedon [22]. The other curves are obtained by adding a constant proportional to the melanin concentration derived from the absorbance spectra (Figure 4A). B Imaginary part of the refractive index, noI, of the wings of three damselfly cases, derived from the absorbance curves together with estimates of the wing membrane thickness.