Morphological and molecular characterization of a new species of the genus Echinorhynchus Zoega in Mller, 1776 (Acanthocephala: Echinorhynchidae) parasitizing the rock greenling Hexagrammos lagocephalus (Pallas) (Scorpaeniformes: Hexagrammidae) from eastern Hokkaido, Japan

A new species of marine-fish-parasitizing echinorhynchid palaeacanthocephalan, Echinorhynchus sasakiaesp. nov., is described based on material from the intestine of the rock greenling Hexagrammos lagocephalus (Pallas) obtained in two localities (Akkeshi and Nemuro) in Hokkaido, northern Japan. Echinorhynchus sasakiaesp. nov. can be distinguished from other congeners by having an oval-shaped proboscis covered with hooks arranged in 14-15 rows, each consisting of 7-10 hooks that are anteriorly short and curved, but posteriorly long and weakly curved. The phylogenetic position of Echinorhynchus sasakiaesp. nov. is inferred based on three gene markers (cytochrome c oxidase subunit I, 18S rRNA, and 28S rRNA) along with relevant sequences from ten congeners available in public databases. Echinorhynchus sasakiaesp. nov. represents the 54th member of the genus and the ninth marine congener known from Japan.