Morphological and molecular characterization of the marine-teleost parasitizing acanthocephalan Echinorhynchus hexagrammi (Syndermata: Palaeacanthocephala) from a new host, Liparis sp. (Actinopterygii: Scorpaeniformes).

ABSTRACT

Originally described from the masked greenling Hexagrammos octogrammus (Pallas, 1814), the palaeacanthocephalan Echinorhynchus hexagrammi Baeva, 1965 has so far been known from seven species in six families of marine teleosts distributed in the Sea of Okhotsk off Sakhalin and in the Northwestern Pacific off Hokkaido, Japan. In this study, we examined the phylogenetic position of E. hexagrammi based on material obtained from the intestine of an unidentified snailfish, Liparis sp., dredged in Akkeshi Bay, Hokkaido, Japan. We performed an analysis using two gene markers, the mitochondrial cytochrome c oxidase subunit I and the nuclear 28S rRNA, along with other sequences available in public databases. In the resulting tree, E. hexagrammi was more closely related to two species complexes, the E. bothniensis Zdzitowiecki and Valtonen, 1987 complex and the E. gadi Zoega in Müller, 1776 complex, rather than to E. brayi Wayland, Sommerville, and Gibson, 1999, E. cinctulus (Porta, 1905), E. salmonis Müller, 1784, and E. truttae Schrank, 1788. The morphology of the examined material herein identified as E. hexagrammi is briefly described. This study represents the first host record of E. hexagrammi from the snailfish family Liparidae.