Hidden in the wrack: spider (Arachnida, Araneae) diversity and new records for Italy from <i>Posidonia</i> banquettes

Posidonia oceanica (L.) Delile beach wrack deposits (banquettes) are a characteristic coastal habitat of the Mediterranean Sea, yet their invertebrate communities remain poorly studied. Here we report the results of a survey from January to November 2024 of the spider fauna (Order Araneae) associated with Posidonia banquettes at Sant’Agostino beach (Civitavecchia, Latium, central Italy), using four complementary sampling methods (surface and underground pitfall traps, Berlese-Tullgren funnel extraction, and visual census). A total of 161 specimens were collected, with 17 species assigned to 11 families among adult individuals. The dominant families were Argyronetidae (39.4%), represented exclusively by Chaerea maritimus Simon, 1885, and Gnaphosidae (33.8%). Three species are recorded for the first time in Italy: Dysdera gamarrae Ferrández 1984, Gnaphosa jucunda Thorell, 1875, and Erigone dentosa O. Pickard-Cambridge, 1894. Additionally, C. maritimus represents a new record for the Latium region and the second record of this species in Italy. The results highlight the faunistic significance of Posidonia banquettes as coastal invertebrate habitat and underscore the importance of these deposits for Mediterranean biodiversity conservation.