Caucasian/Pontic–Mediterranean disjunction and recolonization of Europe by <i>Pomatias</i> (<i>Hyrcania</i>) species (Caenogastropoda, Pomatiidae)

Abstract Lehmann, H., Neiber, M. T., &amp; Hausdorf, B. (2025) Caucasian/Pontic–Mediterranean disjunction and recolonization of Europe by Pomatias ( Hyrcania ) species (Caenogastropoda, Pomatiidae)—Zoologica Scripta, 54, 352‐364. We studied the phylogeny and phylogeography of Pomatias ( Hyrcania ) species (Caenogastropoda: Pomatiidae) to investigate refugia and the causes of disjunctions in Asia anterior and in southeastern Europe. There is a Caucasian/Pontic–Mediterranean disjunction between the ranges of the sister species P. rivularis from the Caucasus region, the Pontic Mountains and southeastern Europe and P. hyrcanus from the coastal region of the southern Caspian Sea in the north and that of P. glaucus along the Mediterranean coast in the south. The disjunct ranges of the Pomatias ( Hyrcania ) species are probably relics of a previously more continuous distribution across Anatolia. They became disjunct as a result of the successive aridification of the Anatolian Plateau, which intensified in the late Pliocene following the uplift of the Anatolian Plateau, as has also been shown for several other taxa. The mitochondrial and nuclear genetic diversity of P. rivularis , the most widespread Pomatias ( Hyrcania ) species, is highest in the populations from the southern Greater Caucasus and the adjacent eastern Pontic Mountains. The southern Greater Caucasus and the coastal regions along the Caspian Sea and the Eastern Mediterranean acted as refugia for the Pomatias ( Hyrcania ) species after the aridification of the Anatolian Plateau. The low genetic diversity of P. rivularis in Eastern Europe and Ciscaucasia suggests that Miocene and Pliocene fossils identified as P. rivularis from these areas cannot be attributed to this species, that the Pomatias ( Hyrcania ) populations became extinct there by the Pleistocene, and that P. rivularis recolonized these areas later, probably only in the Holocene.