A BioBlitz in the Viareggio Marina Area reveals that the North American Rhithropanopeus harrisii (A. A. Gould, 1841) (Decapoda: Xanthoidea: Panopeidae) is spreading further in Italy

BioBlitz surveys are important events aiming to record all the living species in an area within a limited time frame and an important tool to keep track of alien and invasive species. During a BioBlitz held in the Burlamacca Canal (Viareggio Мarina Area, northern Tyrrhenian Sea, Italy), 17 taxa were found, among which an “odd” crab species. Its taxonomic identification was confirmed through an integrative taxonomic approach as the invasive Harris mud crab Rhithropanopeus harrisii (A. A. Gould, 1841). Subsequently,a total of 33 specimens were collected along a 5 × 1 m transect, with a density of 6.6 individuals/m 2.As the sampled material included adults and ovigerous females, we suggest that the species has already established in the area. The pathway of arrival is uncertain, although secondary spreading amidst fouling communities may have played a major role, with specimens arriving from the nearby Livorno area. Future studies may explore relationships between the alien crab and the resident biota as well as whether the species has already colonised Lake Massaciuccoli and its wetlands.