The diversity of tapeworms (Cestoda: Caryophyllidea) of barbels (Cyprinidae: Barbinae) in the western Palearctic: the existence of vicariant lineages and the description of a new species from the Iberian Peninsula.

The caryophyllidean tapeworm has long been regarded as an exceptionally widespread species within its genus, notable for its significant morphological variability. However, with the accumulation of molecular data from different fish hosts, was suspected to represent a species complex. To clarify the true identity of these parasites, a comprehensive morphological and molecular study (using 18S, 28S and ITS2 ribosomal regions) of tapeworms from barbels (Barbinae) across the Iberian Peninsula and the Middle East has been conducted. The results revealed two genetically distinct lineages within the complex. The first lineage, found in and in Iraq and Iran, is genetically congruent with (Cholodkovsky, 1915), originally described from the Sevan khramulya () in Armenia. The second lineage, identified in (type host), and from Portugal and Spain, is described as n. sp. In addition to clear molecular divergence, can be distinguished from by notable morphological differences, including variations in the shape, structure and size of the ovary, the anterior extension of the vitelline follicles, the testes and several morphometric parameters.