Pomphorhynchus bosniacus Kiskarolj & Cankovic 1969 (Acanthocephala), intestinal parasite from the Sava River, Bosnia and Herzegovina: new insights on phylogeny, infection dynamics and histopathology

During 2017, a total of 142 specimens of three cyprinid fish from the Sava River, Bosnia and Herzegovina, were sampled and the presence of the intestinal parasite Pomphorhynchus bosniacus was assessed. Morphological and molecular determination, the latter inferred by sequence analysis of the COI gene and the ITS region, were performed. In addition, the prevalence and intensity of the infection, as well as the pathogenic effect on the host were analysed. Observed morphological features of P. bosniacus were different from P. laevis, whereas COI and ITS sequence analyses revealed none or minimal genetic variability between P. bosniacus and P. laevis from the same geographic area. Histological analysis indicated that the greatest negative effect on the host intestinal tissues was the region by the neck close to the site of parasite penetration. Our results suggest the need for further species revision, as P. bosniacus, a recently evolved sister species of P. laevis complex, shows distinct morphology but limited sequence divergence.