Tracking the Transmission Pathway of Rhadinorhynchus lintoni (Echinorhynchida: Rhadinorhynchidae) in Temperate NE Atlantic

Rhadinorhynchus is a parasitic genus within the order Echinorhynchida (family Rhadinorhynchidae), comprising over 50 species found in marine ecosystems. The life cycle of Rhadinorhynchus species generally includes marine fish as definitive hosts and zooplankton as intermediate hosts. During a routine marine parasitological survey carried out in temperate waters off the NE Atlantic, we recorded adults (from fish) and cystacanths (from mesozooplankton) of an acanthocephalan morphologically corresponding to the genus Rhadinorhynchus. Species identification as R. lintoni was confirmed based on morphological features. Additionally, new genetic data were added for this species based on several molecular markers, including 18S-ITS1-5.8S-ITS2-28S region of the rRNA gene and cytochrome c oxidase subunit 1 gene. Molecular data also provide evidence of a key trophic transmission involving the primary intermediate host—the euphausiid Nyctiphanes couchii—and higher-level consumers (definitive hosts), including the pelagic fish Sardina pilchardus, Scomber scombrus, and Trachurus trachurus. Genetic matching of different life cycle stages of R. lintoni across these host–parasite assemblages underscores the complexity of transmission dynamics within this ecoregion. These findings are discussed in relation to the growing interest of integrating genetic profiles of host–parasite assemblages to understand the life-cycle of marine parasites, especially for those having seafood security and safety concerns.