Living in Deep Mountain Gullies: Distribution and Habitat Patterns of the Hygrophilous Beetle Carabus variolosus in Western Carpathians

We investigated the regional distribution, microhabitat preferences, and associated carabid assemblages of the EU-protected species Carabus variolosus (Coleoptera: Carabidae) within the flysch-dominated Outer Western Carpathians (catchment of Vsetínská Bečva River, Beskid Mts., Czech Republic). Utilizing data from a comprehensive 168-trap pitfall campaign spanning 14 valleys across the entire season, we modeled spatial dependencies alongside multiple environmental and vegetation-derived variables. C. variolosus was highly frequent, representing the sixth most abundant carabid species captured. Regression and redundancy analyses demonstrated an affinity for tufa seepages, rocky stream bottoms, and mesic mountain forest flora, while revealing avoidance of hyper-humid, muddy, or heavily waterlogged sites dominated by tall nitrophilous forbs. Strong spatial effects, explicable to the streams’ network, weakened several habitat associations. Ordination analysis revealed that several hygrophilous and stenotopic forest carabids (Pterostichus unctulatus, Cychrus caraboides) were positively associated with C. variolosus, whereas several widespread montane forest species showed the opposite association. We conclude that while C. variolosus remains locally common in unmanaged headwaters, its formal protection provides an ecological umbrella for unregulated streams and forest wetlands across the wider Carpathian landscape.