Lights in the Mediterranean night: firefly distribution in Italian islands revealed through citizen-science and scientific field-work

Islands represent living laboratories for investigating biodiversity and animal colonization patterns. Despite this, many insect groups remain poorly investigated in these systems, particularly within the Mediterranean Basin. Fireflies (Coleoptera, Lampyridae), besides their ecological, cultural, and conservation relevance, are no exception. Here, we present the first comprehensive synthesis of firefly occurrence across major and minor Italian islands, integrating standardised nocturnal surveys conducted within the L.U.C.E. (“Lighting up the understudied charismatic fireflies of Europe”) project with validated citizen-science records derived from the iNaturalist platform. This integrative approach enabled a complete assessment of species occurrence, spatial patterns, and the complementary value of structured fieldwork and citizen-generated records. Surveys were conducted in Italy between 2023 and 2025 across two major islands (Sardinia and Sicily) and thirteen small islands. Occurrence data were analysed to quantify taxonomic richness, island occupancy, and the relative contributions of each data source across islands. Overall, we recorded 10 taxa (including species and subspecies) on Italian islands, representing 50% of the firefly species currently recognised at the national level. Species richness and record abundance were significantly higher on larger islands. In contrast, small islands generally hosted one or two taxa, reflecting classic island biogeography patterns and limited dispersal abilities linked to firefly life-history traits. Comparison between data sources revealed a strong complementarity. Citizen-science records provided broad spatial coverage, particularly on easily accessible and frequently visited islands, but often lacked fine taxonomic resolution. Conversely, targeted surveys yielded fewer records overall but were essential for detecting poorly known populations, achieving accurate species-level identification, and documenting rare or previously unrecorded taxa. Notably, the detection of Lampyris pallida on Linosa, confirmed through DNA barcoding, represents the first record of this species for Italy.