Deepest digenean parasite: Molecular evidence of infection in a lower abyssal gastropod at 6,200 m

Abstract

Little is known about the diversity and ecology of digenean parasites in the abyssal ocean (3500–6500 m deep) with previous occurrence records down only to 4877 m. Here, we report a 28S rDNA sequence of the fish digenean genus Lepidapedon (Lepidapedidae), amplified from DNA extract of a velutinid gastropod collected at 6185–6221 m in the Kuril–Kamchatka Trench, Northwest Pacific. This represents the deepest record for the platyhelminth class Digenea and, to our knowledge, for any group of fish parasites. Our finding also verifies for the first time that abyssal lepidapedids exploit benthic snails as intermediate hosts. The present species of Lepidapedon presumably accomplishes its life cycle in the lowermost abyssal zone with macrourid fish as the definitive host.