On the Neoechinorhynchus agilis (Acanthocephala: Neoechinorhynchidae) complex, with a description of Neoechinorhynchus ponticus n. sp. from Chelon auratus in the Black Sea

We recognize four species in the Neoechinorhynchus agilis complex. We studied specimens of Neoechinorhynchus (Hebesoma) personatus Tkach, Sarabeev & Shvetsova, 2014 from Mugil cephalus in the Mediterranean Sea off Tunisia and in the Black Sea, and also specimens of Neoechinorhynchus ponticus n. sp. from Chelon auratus Risso in the Black Sea. Specimens from M. cephalus at both locations were similar. All structures of N. ponticus n. sp. were considerably smaller than those of N. personatus. Two other species of the N. agilis complex are recognized: Neoechinorhynchus agilis (Rudolphi, 1819) sensu stricto from various hosts in the Atlantic and the Mediterranean, and Neoechinorhynchus yamagutii Tkach, Sarabeev & Shvetsova, 2014 from M. cephalus and Planiliza haematocheila in the Pacific, especially the Sea of Japan. Neoechinorhynchus dimorphospinus Amin & Sey, 1996 from marine fish in the Persian Gulf and the Pacific Ocean off Vietnam may be a candidate for membership in the N. agilis complex. X-ray scans of gallium cut and intact hooks of N. personatus and N. ponticus showed differences in the mineral content of hooks with higher sulfur levels in smaller hooks and in hooks from specimens in the Black Sea compared to specimens from the Mediterranean. The relatively high genetic differences between N. ponticus n. sp. and other species of Neoechinorhynchus using a partial 18S rDNA dataset support its independent status. Neoechinorhynchus ponticus n. sp. and N. personatus have a common ancestor with species of Neoechinorhynchus collected from saltwater fish.