Hypotheses for the historical biogeography of B. variegata in the Balkan Peninsula in respect to paleo-mountain ranges and the time-calibrated phylogeny (Fig. 2). A The initial divergence separated the Carpathian (ancestral variegata, red) from the southern (ancestral scabra, green) populations, potentially as early as the Late Miocene. B The Apennine population (pachypus, yellow) subsequently originated from the latter. C During the Pleistocene, the southern population diversified into scabra (green) and rhodopensis subsp. nov. (purple); variegata (red) captured scabra mtDNA in the northern Dinarides and spread it across northwestern Europe during the post-glacial colonization. TMM: Thrace-Macedonian massif, including Rila (Ri), Pirin (P) and Rhodope (Rh). Layout map modified from Jablonski (2017a) based on Popov et al. (2004).