Scardinius hesperidicus

Alexander, Timothy & Seehausen, Ole, 2021, Diversity, distribution and community composition of fish in perialpine lakes – “ Projet Lac ” synthesis report, Eawag: Swiss Federal Institute of Aquatic Science and Technology : 124

The presence of S. hesperidicus (southern rudd) north of the Alps was first revealed by Projet Lac in the first lake sampled by the project (Lake Morat). In the course of the further surveys, the southern species was recorded in a total of 12 northern perialpine lakes, as well as in Lake Sils ( Table 16). It was also reported to us with photographic documentation from Lake Poschiavo (Marcel Michel, personal communication). In most lakes, the presence of S. hesperidicus was evident from the phenotype, including by the distinct colouration of the fins in adult fish. However, there were also two northern lakes (Thun and Zurich) where the presence of the southern species was revealed only by barcoding of the mitochondrial gene COI. Mismatches between phenotype and barcode were observed in several lakes suggesting some level of hybridization and backcrossing.