The present volume is the ninth of the series Guide to the Butterflies of the Palearctic Region, and the third on the family Lycaenidae. The series, including the present volume, has dealt with over 500 species, more than 200 belonging to the family Lycaenidae. The authors of this volume, Lycaenidae Part 3, have covered respectively the following subjects: Z. Weidenhoffer the tribes Tomarini and Aphnaeini and G. C. Bozano the tribe Theclini (partim). As in the previous issues of the series, the availability of specimens from remote and little known areas, the study of most of the available literature and the access to museums collections have allowed to clarify many taxonomic problems. All the taxonomic changes established in the present volume are listed after the introduction chapter. In the treatment of the tribe Aphnaeini the author has adopted a very wide interpretation of the boundaries of the Palearctic region, in order to give to the reader the largest possible overview of the existing species.