An update of the known distribution and status of Cherax spp. in Italy (Crustacea, Parastacidae)

To date, only two Cherax species have been reported to occur in Italy, i.e., C. destructor Clark, 1936 and C. quadricarinatus (von Martens, 1868), both in the wild and in aquaculture farms. Therefore, we aimed to update their current status and distribution in Italian mainland and Sicily. In addition, we investigated the origin of their known populations, and their possible routes of invasion. In order to genetically characterize the Cherax populations occurring in Italian inland waters and aquaculture facilities, the barcode region of the mtDNA gene cytochrome oxidase subunit I was sequenced in the available specimens originating from an aquaculture facility and a museum collection. The sampling campaigns conducted in 2021 did not lead to the collection of any Cherax individuals in the sites where the species was formerly reported to occur. The recent failures to detect Cherax spp. from Italian inland waters might be due to the inability of the species to cope with the Italian climate, which is likely for C. quadricarinatus but less so for C. destructor, to the possible impact of the alien red swamp crayfish Procambarus clarkii (as well as its indirect impact i.e., the spread of the crayfish plague for which yabby is susceptible), which occurs in both the sites where C. destructor was reported in Italy, or to the burrowing habits of the species, which might lead to overlook their presence when present at low densities. In the light of the well-known impact of invasive crayfish and considering the scant knowledge about the current distribution and status of Cherax species in Italy, a regular monitoring of their possible presence is recommended.