The Balkan Peninsula represents one of the hottest biodiversity spots in Europe. However, the invertebrate fauna of this region is still insufficiently investigated, even in respect of such well-studied organisms as Lepidoptera. Here we use a combination of chromosomal, molecular and morphological markers to rearrange the group of so-called anomalous blue butterflies (also known as ‘brown complex’ of the subgenus Agrodiaetus Hübner, [1822] and as the Polyommatus (Agrodiaetus) admetus (Esper, 1783) species group) and to reveal its cryptic taxonomic structure. We demonstrate that Polyommatus
aroaniensis (Brown, 1976) is not as widespread in the Balkans as was previously thought. In fact, it has a dot-like distribution range restricted to the Peloponnese Peninsula in South Greece. Polyommatus
orphicus Kolev, 2005 is not as closely related to the Turkish species Polyommatus
dantchenkoi (Lukhtanov & Wiemers, 2003) as was supposed earlier. Instead, it is a Balkan endemic represented by two subspecies: Polyommatus
orphicus
orphicus (Bulgaria) and Polyommatus
orphicus
eleniae Coutsis & De Prins, 2005 (Northern Greece). Polyommatus
ripartii (Freyer, 1830) is represented in the Balkans by an endemic subspecies Polyommatus
ripartii
pelopi. The traditionally recognized Polyommatus
admetus (Esper, 1783) is shown to be a heterogeneous complex and is divided into Polyommatus
admetus sensu stricto (the Balkans and west Turkey) and Polyommatus
yeranyani (Dantchenko & Lukhtanov, 2005) (east Turkey, Armenia, Azerbaijan and Iran). Polyommatus
nephohiptamenos (Brown & Coutsis, 1978) is confirmed to be a species with a dot-like distribution range in Northern Greece. Finally, from Central Greece (Timfristos and Parnassos mountains) we describe Polyommatus
timfristos Lukhtanov, Vishnevskaya & Shapoval, sp. n. which differs by its haploid chromosome number (n=38) from the closely related and morphologically similar Polyommatus
aroaniensis (n=47-48) and Polyommatus
orphicus (n=41-42). We provide chromosomal evidence for three separate south Balkan Pleistocene refugia (Peloponnesse, Central Greece and Northern Greece/South Bulgaria) and stress the biogeographic importance of Central Greece as a place of diversification. Then we argue that the data obtained have direct implications for butterfly karyology, taxonomy, biogeography and conservation.