The elevation of a unique population of (Acanthocephala: Polymorphidae) from the Caspian seal, , in the Caspian Sea to n. sp.

An isolated population of 700 specimens initially described as (Rudolphi, 1802) Lühe, 1904 and currently reassigned to n. sp. was collected from one young male Caspian seal, (Gmelin) in the southern land-locked Caspian Sea in April 2009. Collected worms were morphologically unique compared with those reported by other observers in open waters, especially in shape and distribution of proboscis hooks and trunk spines, dorso-ventral differences in proboscis hooks and their organization, the baldness of anterior proboscis, consistently smaller size of trunk and testes, larger eggs, the rough egg topography, epidermal micropores, and variations in the female gonopore. Molecular data from the internal transcribed spacer region of rDNA and the mitochondrial cox1 gene was also provided to supplement the morphological study of the new species.