The nomenclature follows the 2011 edition of Fauna Europaea with some modifications.
This species was recently separated from L. reali Reissinger, 1989 based on molecular studies (Dinca et al. 2011a). The Balkan populations, previously identified as L. reali, belong to L. juvernica (Shtinkov et al. 2016).
There seem to be no morphological characters allowing reliable separation from P. napi (Coutsis and Ghavalás, 2001; Kolev, 2009). Reports of this species from Bulgaria need reexamination (Kolev, 2009). In this situation, I believe it is most expedient to treat this taxon as a subspecies of P. napi following Geiger and Scholl (1985).
P. eroides has been treated as a subspecies of P. eros (Ochsenheimer, 1808) by Vodolazhsky and Stradomsky (2008) based on the small genetic differences between the two taxa. Both have been reported for Bulgaria, but no reliable records of nominotypical P. eros exist (Kolev, 2009). To avoid confusion, for now I retain the name P. eroides for this taxon.
Kolev (2005) has convincingly demonstrated that P. andronicus is a distinct species from P. icarus (Rottemburg, 1775) based on well pronounced morphological and ecological differences between the two taxa. They have been recently synonimized based on DNA results (Wiemers et al., 2010). One must remember though that as an identification tool, DNA barcoding has its limitations (Dinca et al., 2011b); it should be regarded as complementing other taxonomic techniques rather than superseding them. The established genetic similarity between P. andronicus and P. icarus does not refute the evidence for their specific distinctness; rather, it should motivate further research into the two taxa. I therefore consider them distinct species.
The correct name for the species previously reported from Bulgaria as Melitaea telona or M. punica is in fact M. ornata (Tóth & Varga, 2011).
The following species, which have been reported from Bulgaria based on questionable data or for which no reliable records exist (Kolev, 2002; 2009), have been excluded from the list: Muschampia proto (Ochsenheimer, 1808), Archon apollinus (Herbst, 1798), Leptidea morsei (Fenton, [1882]), Colias chrysotheme (Esper, [1781]), Polyommatus eros (Ochsenheimer, 1808), Pseudochazara graeca (Staudinger, 1870), Pseudochazara geyeri (Herrich-Schäffer, [1846]), and Boloria titania (Esper, [1793]).
Two species previously reported from Bulgaria have in fact never been found in the country: Colias myrmidone and Polyommatus aroaniensis. More information can be found in the Butterflies of Bulgaria Android App.
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Wiemers M., B. V. Stradomsky, and D. I. Vodolazhsky, 2010. A molecular phylogeny of Polyommatus s. str. and Plebicula based on mitochondrial COI and nuclear ITS2 sequences (Lepidoptera: Lycaenidae). Eur. J. Entomol. 107: 325–336.