From accidental citizen-science observations to genetic confirmation: How to spot new hidden invaders

The crested porcupine Hystrix cristata is the largest rodent in Italy, where it is strictly protected according to national and international laws. The species is almost exclusively nocturnal and quite elusive: its presence may be yet recorded through the detection of quills lost on the ground. In the last 40 years, the crested porcupine showed a remarkable range expansion in Italy. In 2013, in the framework of the www.naturaesocialmapping.it recording site, a web page devoted to H. cristata was set up. The aim of the project was to give people the opportunity to contribute to a continuous updating of the distributional map of this rodent. Lost quills were also collected by citizen-observers, as being easily available sources of DNA. This web page allowed us to detect the first evidence of the presence of another species of porcupine free-ranging in Italy (photos and quills): the Indian porcupine H. indica. Species identification was carried out through DNA barcoding analysis, since it cannot be performed only through quill morphology. We increased the international genetic database with sequences of both species, so to allow a rapid identification of samples through molecular analyses. Both species were introduced to Italy by humans. Our findings also support the relevance of citizen science contribution in the process of updating species’ distribution range and the potential of spotting new invasive species.