Potential habitats of Phengaris teleius, containing the food plant of the butterfly (Sanguisorba officinalis L.) were identified using Google Earth satellite images and with the help of local rangers. In order to check whether P. teleius lives on the Hungarian side of the border, we visited four localities inside of the National Park Kiskunság on 6th of August 2015: 1. Rívó-erdő és semlyék, 2. Ásotthalmi láprét (Csodarét), 3. Csipak semlyék and 4. Domaszéki canal (north of Zákányszék). The distribution of P. teleius in Serbia has been studied since 2012 and here the results are summarised, wtih the addition of the recently discovered location.

The new records of Phengaris teleius in Hungary and Serbia shows that the local populations may be more interconnected than previously thought (Popović et al. 2014). This could have great conservation importance, knowing the small migration distances and sedentary character of this butterfly species (Nowicki et al. 2005). As maximal migrations reach up to 5 km, at least some exchange of individuals is possible between local populations (Nowicki et al. 2014, Nowicki et al. 2005).

The distribution of P. teleius in Serbia is probably limited only to the study area and is now well known due to the considerable research efforts made since its discovery in 2012. However, more detailed studies are required in south-eastern Hungary for mapping its range and habitats. These populations are on the southern border of the species distribution in Europe (Wynhoff 1998), thus more conservation importance and efforts is required for their conservation (Bourn and Thomas 2002).

On some sites hosting P. teleius, we also observed the Large Copper, Lycaena dispar (Haworth 1802), another Natura 2000 species that can be found in wetland habitats. This increases the conservation value of the remaining wet meadow fragments. Such meadows are now among the most important habitats for the survival of threatened butterflies in Europe and the persistence of P. teleius depends on their appropriate management, including mowing regimes (Settele et al. 2005). In addition, the survival of this butterfly is highly dependent on the presence of host plant and host ants, both being sensitive to management practice. Recent study has shown that the local populations in Serbia are still exceptionally numerous, although a few local extinctions are recorded on a small scale (Popović, unpublished data). There is a need for additional research on ecology of P. teleius in order to adapt habitat management to the local needs of present butterfly populations. For example, in similar habitats in Hungary, low grazing was indicated as adequate management practice (Batáry et al. 2007) and mowing regimes have been proven important for its conservation in Serbia (Popović et al. 2014).

The results of scientific studies should be applied in joint conservation plans for P. teleius in both Serbia and Hungary, especially because the species conservation status is known to be unfavourable. This is easy to achieve since the studied populations are located inside of the protected areas, where some active management practice already exsist. The present locations of the species should be urgently included into the official ecological network of the Republic of Serbia and planned for inclusion within the upcoming Natura 2000 areas. Special attention should be given to preserve current water regimes inside the protected areas, create better connection between isolated habitats and monitor remaining populations of P. teleius.