Microstructures and nanostructures of high Andean Penaincisalia lycaenid butterfly scales (Lepidoptera: Lycaenidae): descriptions and interpretations

Abstract

The scales of one high Andean eumaeine lycaenid butterfly species with pale dorsal coloration and four species with vivid dorsal colour were investigated using field emission scanning electron microscopy. The micro‐ and nanostructures are illustrated, described, measured, and interpreted. The vivid colours in the species are caused by a pepper‐pot nanostructure of Urania‐type scales. This nanostructure is a three‐dimensional lattice within the body of the individual scale. The scales of the non‐vivid orange species are lacking this nanostructure and the surfaces of their scales show high microstructure irregularities. This absence of vivid colour may be correlated with thermal regulation. The irregularity of the scale microstructures suggests a heavy environmental pressure on the populations sampled. Previously unknown structural variations of Urania‐type scales are also described. The existence of closed scale microcell structures, explained as an apomorphic character in the tribe Eumaeini, most probably evolved independently several times. It is hypothesized that scale micro‐ and nanostructure modifications develop syntopically within a population, which in turn can lead to rapid diversification.

Keywords:

• Andes
• discoloration
• Eumaeini
• irregularity
• Lycaenidae
• monomorphy
• Penaincisalia
• scale microstructure
• scale nanostructure
• South America
• sympatric speciation
• Thecloxurina
• thermal regulation

Acknowledgements

The present paper is written in the frame of the theme “Comparative physiomorphological and thermodynamical investigations in Lycaenidae” supported by the Hungarian Scientific Research Fund (OTKA, grant no. 42972). A part of this work was carried out under a Royal Society Fellowship awarded to the first author in 2003, who thanks Mr Phillip R. Ackery (The Natural History Museum, London) for hosting collection studies and for his support. The work was also supported in part by EU6 BIOPHOT/NEST grant. We express jointly our thanks to Dr Naomi Pierce (USA), Mr Alan Heath (UK) and Dr Kurt Johnson (USA) for linguistically editing and reviewing the manuscript, pointing out some weaknesses, not all of which were linguistic.

Dedication

The present paper is dedicated to the memory of John Nevill Eliot (died in 2003), who elaborated the higher classification of Lycaenidae (Eliot 1973). J. N. Eliot was a friendly colleague of Zs. Bálint, who visited him on 16 August 2000 at his home. During that visit J. N. Eliot showed him a manuscript that he had produced at that very advanced age in his life. The work was impressive, and was actually another significant step in lycaenid systematics. This paper was his last opus: Tilley and Eliot 2002. An offprint of this paper reached Zs. Bálint on 26 August 2002 with the dedication: “Zsolt: Best wishes. John”.