UV-reflectivity of parafocal eyespot elements on butterfly wings in normal and abnormal specimens

Mouyu Yang, Ahti Pyörnilä, V Benno, Meyer-Rochow Yang, A Meyer, Mouyu Yang, V Benno Meyer-Rochow
Rochow, V. B. 2004: UV-reflectivity of para-focal eyespot elements on butterfly wings in normal and abnormal specimens.-Entomol. Fennica 15: 34-40. An unusual specimen of Aglais urticae, lacking characteristic UV-reflecting parafocal eyespot elements along the margins of both fore and hind wings, is compared with normal, wild-type specimens. Wing scales, responsible for generating structural coloration, are missing in the abnormal individual and have been replaced with a type that is typical of
more » ... pigment-based colours. Other modifications seen in the abnormal specimen include firstly, a distal expansion of a uniformly brown region, that otherwise occupies a proximal position on the hind wings of the wild type, and secondly, the lack of a characteristic orange cross-vein band that runs proximal to the parafocal eyespot elements on the hind wing. The differences in coloration between abnormal and wild type are seen as evidence of a proximal-distal developmental axis (originally proposed by Nijhout 1991) and support a view recently aired by Beldade and Brakefield (2003). It is now clear that studies on butterfly eyespot development must consider not only pigment-containing scales, but also the structurally modified scales responsible for physical colours, i.e. UV reflectivity.