Abstract
The structural scales that give rise to the characteristically vivid green, blue or violet iridescent colours of some 47 species of Lycaenidae and 7 species of Riodinidae have been examined by optical and scanning electron microscopy. Most species of Lycaenidae examined produce iridescent colours via a multilayer elaboration within the lumen of the scale into a Urania-type microstructure. The multilayers were found to be perforated and possess a characteristically complex and typical microstructure, referred to as a pepper-pot structure. In addition, colour production by a Morpho-type structure was unexpectedly found in some species of the subfamily Lycaeninae. This microstructure results from an elaboration of flutes on the ridges and is quite distinct from Morpho-type scales found in the Riodinidae, which are derived from scutes. The phylogenetic and taxonomic usefulness of scale microstructure is considered and it is speculated that within Lycaeninae Morpho-type scales may have evolved by transition from Urania-type scales.
