The potential importance of the mainstream for genetic dispersal on the endemic Salamandrina perspicillata Savi, 1821 (Amphibia, Salamandridae) within Val Borbera Valley (appennin chain, NW Italy).

A particularly interesting finding from studies conducted in the Borbera/Agnellasca drainage, in Alta Val Borbera Natural Park (AL), is the observation of multiple recurrent reproductive sites of Salamandrina perspicillata along the borders of the mainstream. These sites were found in an environmental context that is notably different from, and more dynamic than, those typically described in the literature. This observation is a novelty for the reproductive behaviour of this species, as until now it was thought to reproduce exclusively in small and extremely stable environments, such as springs, fountains and high tributary. The recurrent discovery of eggs and larvae of Salamandrina perspicillata in areas of the main shaft suggests that the reproduction in such environment is not a sporadic or random fact, but it can play an important role in the natural and ecological history of the populations and in the survival of the species. The mainstream could therefore represent a biological corridor that allows the contact and the genetic exchange between populations present in the hydrographic network. Preliminary evaluations were also conducted on the genetic spectrum of the recently discovered population outside its known range, in the Savona area, SIC IT1324011 “Monte Ravinet – Rocca Barbena”, and the population in the ZSC/ZPS IT1180026 “Capanne di Marcarolo”. Therefore, another objective of this work was to update the distribution range of Salamandrina perspicillata within the protected areas managed by the Appennino Piemontese park. The sampling campaigns took place between 2022 and 2023, actively searching for egg clutches, larvae, and adults. Tissue samples were taken from larvae and adults by clipping the tip of the tail, while embryos were collected from egg clutches. All samples were preserved in ethanol (95%) to allow genetic analyses conducted by Nurhayat Özdemir. Six microsatellite loci were characterized, and the cluster assignment of each subpopulation was determined. The analyses show an increase in genetic diversity from west to east and a high FST value in the Savonese population, probably indicating a genetic distance. Regarding Val Borbera, the data confirm the hypothesis of biological corridor, as it possessed the highest number of alleles, private alleles, and the greatest allelic richness. Additionally, it did not show significant differences from surrounding populations and exhibited similar genetic patterns, especially with neighbouring populations. These results bring more attention to the management and conservation of the species in the Val Borbera area for the use of a new environment, while in the future more in-depth analyzes may be carried out on the Savonese population to better understand its taxonomic identity.