Hermann’s tortoise in Calabria: filling key knowledge gaps in a Western Mediterranean evolutionary hotspot

Abstract The Hermann’s tortoise Testudo hermanni Gmelin, 1789 is one of Europe’s most endangered terrestrial chelonians, with highly fragmented populations across its range, particularly in the western part. Calabria (southern Italy) hosts populations of exceptional conservation value, recently identified as a hotspot of genetic diversity for the species. However, ecological, distributional, and morphological data for these populations remain scarce. In this study, we combined intensive field surveys, morphometric analyses, and information derived from local ecological knowledge to provide the most comprehensive assessment to date of the Hermann’s tortoise in Calabria. Our results substantially expand the known regional distribution, documenting its presence in 49 grid cells compared to the 16 previously reported. A total of 172 adult individuals were measured, revealing clear sexual dimorphism and significant morphological differences between the northern and southern populations, with tortoises from Aspromonte being larger. Habitat analyses indicate that the species occupies a wide range of Mediterranean environments, from lowland scrub to high altitudes in the Aspromonte massif, with a preference for open, thermophilic habitats on loose soils. Due to its ecological plasticity, most populations occur outside protected areas and are threatened by habitat loss, fragmentation, and poaching. Local ecological knowledge, despite some limitations, proved valuable for extending distribution knowledge in poorly studied areas. This study provides an updated and integrated overview of the morphological, ecological, and distributional features of T. h. hermanni in Calabria, supporting conservation planning for one of the most genetically diverse populations in the Western Mediterranean.