News from the western front: occurrence of Mediterranea depressa (Sterki, 1880) (Mollusca: Gastropoda: Oxychilidae) in the Vosges and Jura Mountains (north-eastern France)

We report here the first record of Mediterranea depressa (Sterki, 1880) in the north-eastern quarter of France, in the Vosges and Jura massifs. After the fortuitous discovery of some shells attributed to M. depressa in the southern Vosges Mts., an extensive sampling campaign was carried out both in the Vosges and in the Jura Mts. In total, about 20 shells and seven live specimens were found at eight localities, which, according to the present state of our knowledge, represent its north-western range limit. The species was found exclusively under stones of rocky slope screes on siliceous and calcareous substrates. Some of these habitats could be described as Mesovoid Shallow Substratum. It is not clear whether the rarity of the species is an effect of under-sampling or of its small size and unusual habitat or/and to intrinsic rarity due to isolated populations at the distribution limits of the species. The extreme north-eastern quarter of France constitutes an oceanic-continental transition zone where about thirty gastropod species from Central and Eastern Europe are currently documented at the western limit of their ranges.