“…Second, the European P. fuscus consists of independent Balkan (fuscus) and Black Sea (vespertinus) ecomorphologically similar lineages of Plio-Pleistocene origin that now meet in the Eastern European plains (Borkin et al, 2003;Crottini et al, 2007;Litvinchuk et al, 2013;Suriadna, Mikitinets, Rozanov, Yu, & Litvinchuk, 2016) and hybridize along a narrow transition zone (Litvinchuk et al, 2013). Third, P. syriacus features cryptic Asian (P. s. syriacus) and European (P. s. balcanicus) subspecies, supported by divergent mitochondrial and nuclear haplotypes, as well as allozyme variation, perhaps as old as the Pliocene (Ehl, Vences, & Veith, 2019;Litvinchuk et al, 2013;Veith, Fromhage, Kosuch, & Vences, 2006). So far, no phylogeographic work has focused on P. syriacus, and its diversity, distribution and the potential reproductive isolation between lineages remain unknown.…”