Ongoing Westward Expansion of the Carpathian Blue Slug Bielzia coerulans into Central Europe

Increasing traffic and trade, the modification of landscapes by humans, and climate change facilitate the dispersal of certain species that are adapted to anthropogenic habitats. When species’ natural dispersal limitations are overridden by human-mediated dispersal, the composition of communities can be determined by the prevailing climate, rather than reflecting biogeographic realms, as has been shown for terrestrial snails (Capinha et al., 2015). The size of a species’ native range affects the probability that it will become invasive (Pyšek et al., 2009). Thus, endemic species with small geographic ranges rarely become invasive. Here we report a new record of the Carpathian blue slug Bielzia coerulans (Bielz, 1851) (Gastropoda: Limacidae) from the Bavarian Forest in Germany, which together with other records might indicate an ongoing expansion of this characteristic representative of the Carpathian fauna westward. The discovery of Bielzia coerulans was a fortuitous result of entomological excursions in the Bavarian Forest in southern Germany. The identification of the species was based on the external morphology (Fig. 1) in accordance with characteristics given by Wiktor (1989) and Wiese & von Glasow (2013). A single adult specimen of the Carpathian blue slug Bielzia coerulans (Fig. 1) was discovered under a large stone in the nature reserve “Pfahl bei der Ruine Weißenstein” about 800 m southeast of Regen-Weißenstein (48°56’38.87”N, 13°09’29.16”E), at 710 m a.s.l., in the Bavarian Forest in Germany on 9 August 2017 by the second author. The specimen was immediately identified by its characteristic blue colour and recorded. Further searching did not result in the discovery of additional specimens. MALACOLOGIA, 2019, 62(2): 373–375