The Carpathians are one of the most extensive mountain ranges of the European Alpine System (Ozenda 1985) and a widely recognised mountain biodiversity hotspot in Europe (Schmitt 2009; Bálint et al. 2011; Mráz and Ronikier 2016). Additionally, although well-delimited from geomorphological point of view, the Carpathian Region (with its subunits, i.e. the Western, Eastern and Southern Carpathians, the Apuseni Mountains and the Transylvanian Basin) is closely linked through its shared biotic components with the neighbouring mountainous regions of the Alps, the Hercynian Massif, and the Balkan Peninsula (Stevanović 1996; Coldea 2003; Aeschimann et al. 2004; Puşcaş and Choler 2012; Jablonski et al. 2016).