Prevalence and sequence comparison of Phyllodistomum folium from zebra mussel and from freshwater fish in the Ebro River.

We utilised DNA analysis to detect the presence of the digenean Phyllodistomum folium in three cyprinid species, Scardinius erythrophthalmus, Cyprinus carpio and Rutilus rutilus. DNA sequencing of the region containing the genes ITS1-5.8S-ITS2 revealed 100% sequence identity between DNA from the sporocysts found in zebra mussels and DNA from adults located in the urinary system of 29 cyprinid fish. A second genetically different (variation=1.6%) sequence was observed in two samples from R. rutilus. In our opinion, the existence of a complex of species reported as P. folium is supported by recent genetic studies, including our own results. The overall prevalence of P. folium in mussels from the Ebro River was 4.67% in 2006, although during the summer months the rates frequently exceeded 10%.