Unpublished Mediterranean records of marine alien and cryptogenic species

Good datasets of geo-referenced records of alien species are a prerequisite forassessing the spatio-temporal dynamics of biological invasions, their invasivepotential, and the magnitude of their impacts. However, with the exception of firstrecords on a country level or wider regions, observations of species presence tendto remain unpublished, buried in scattered repositories or in the personal databasesof experts. Through an initiative to collect, harmonize and make such unpublisheddata for marine alien and cryptogenic species in the Mediterranean Sea available, alarge dataset comprising 5376 records was created. It includes records of 239 alienor cryptogenic taxa (192 Animalia, 24 Plantae, 23 Chromista) from 19 countriessurrounding the Mediterranean Sea. In terms of records, the most reported Phyla indescending order were Chordata, Mollusca, Chlorophyta, Arthropoda, and Rhodophyta.The most recorded species was Caulerpa cylindracea, followed by Siganus luridus,Magallana sp. (cf. gigas or angulata) and Pterois miles. The dataset includesrecords from 1972 to 2020, with the highest number of records observed in 2018.Among the records of the dataset, Dictyota acutiloba is a first record for theMediterranean Sea. Nine first country records are also included: the alga Caulerpataxifolia var. distichophylla, the cube boxfish Ostracion cubicus, and the cleanershrimp Urocaridella pulchella from Israel; the sponge Paraleucilla magna fromLibya and Slovenia; the lumpfish Cyclopterus lumpus from Cyprus; the bryozoanCelleporaria vermiformis and the polychaetes Prionospio depauperata andNotomastus aberans from Malta.