Expanding Insular Presence of the Giant Water Bug Lethocerus patruelis (Stål, 1854) Across the Aegean Islands: New Evidence of an Emerging Archipelagic Distribution

Lethocerus patruelis (Stål, 1854), the sole European belostomatid, is an apex invertebrate predator in Mediterranean freshwater systems and a species known for its strong flight capacity and growing range expansion record. While its continental distribution in Greece is increasingly well documented, its presence across the Aegean islands has remained poorly characterized, with historical records scattered and often unpublished or fragmentary. Here, we present new, photographically verified records that substantially refine the species’ insular distribution and provide the first coordinated synthesis of its emerging archipelagic footprint. These include the first confirmed live individual from Samothraki and a newly documented specimen from Naxos, recovered beside a nearly desiccated summer stream indicating a very recent arrival. When integrated with additional verified observations from Sifnos, Ikaria, Chios, Euboea, Tilos, and Crete, as well as earlier published records, a coherent spatial pattern emerges. Rather than isolated vagrants, the records align along three longitudinal dispersal axes spanning the northern, central, and southern Aegean. These axes reflect plausible biological and anthropogenic pathways influenced by regional winds, maritime transport, and the distribution of natural and artificial freshwater habitats. Collectively, the evidence indicates that L. patruelis is undergoing a sustained, multi-vector archipelagic expansion, underscoring the importance of integrating citizen-science observations with targeted field documentation to monitor freshwater biodiversity across Mediterranean islands.