Background: Due to its interesting life cycle, vulnerability and conservation importance, the butterfly Phengaris teleius is one of the most studied insects in Europe. It was discovered in Serbia only in 2012 and there were no data on its distribution from the south of Hungary.
New information: Phengaris teleius was recorded for the first time in four localities in Hungary and in additional locality in Serbia. This suggests that the local populations are more interconnected than previousely thought and that conservation efforts should be done in collaboration between the two countries. All localities are inside protected areas and management measures for preserving several target species already exist. This represents a solid base for the conservation of newly discovered populations of P. teleius.
Keywords: Natura 2000; Nature conservation; Scarce Large Blue butterfly; species distribution.