Unpublished Mediterranean and Black Sea records of marine alien, cryptogenic, and neonative species (III)

Abstract

To enhance regional knowledge of invasive alien species (IAS), cryptogenic, and neonative species, this study compiles previously unpublished records from the Mediterranean and Black Seas via contributions from 227 marine experts. The open-access dataset includes 7,422 records from 21 countries, representing 275 taxa: 222 Animalia, 44 Plantae, and 9 Chromista. Seventy-two percent of records were collected in 2021–2024 while most reports were from Lebanon, Greece, Cyprus, Italy, and Romania. The most frequently recorded species were Siganus luridus, S. rivulatus, Callinectes sapidus, Caulerpa cylindracea and Parupeneus forsskali. Several records are biogeographically notable: basin-level firsts include Dynoides amblysinus and Symplegma rubra, and the first confirmed occurrence of Malmgrenia mcintoshi. National firsts include Mesanthura cf. romulea, Mitrella psilla, and Syllis ergeni (Algeria); Exogone breviantennata, Jassa marmorata, Leodice antennata, and Syllis schulzi (Cyprus); Botrylloides niger and Polyandrocarpa zorritensis (Greece); Microcosmus exasperatus, Phallusia nigra, and Stypopodium schimperi (Italy); Chaetozone corona (Slovenia); Pseudodiaptomus marinus and Symplegma brakenhielmi (Spain); Aquilonastra burtoni, Siphonaria crenata, and Sphaeroma walkeri (Syria) and Distaplia bermudensis (Tunisia). In the Black Sea, Hydroides dianthus, Ferosagitta sp., and a zoea III of Palaemon macrodactylus are newly documented from Romanian waters. Beyond listing records, this compilation supports spatiotemporal analyses relevant to management. The sharp post-2021 increase reflects both species spread and intensified surveys, and habitat-labelled records include harbours/marinas and shellfish aquaculture settings, consistent with pathway hotspots. By revealing where and when detections concentrate—and which taxa dominate—these data can guide early detection, risk prioritization, and targeted biosecurity, while identifying under-reported coastlines.