Pseudopecoelus mccauleyi n. sp. and Podocotyle sp. (Digenea: Opecoelidae) from the deep waters off Oregon and British Columbia with an updated key to the species of Pseudopecoelus von Wicklen, 1946 and checklist of parasites from Lycodes cortezianus (Perciformes: Zoarcidae)

Pseudopecoelus mccauleyi n. sp. (Opecoelidae: Opecoelinae) is described from the intestine of the bigfin eelpout, Lycodes cortezianus (Gilbert, 1890) (Perciformes: Zoarcidae), collected at 200–800 m depths in the Northeastern Pacific Ocean off Oregon and Vancouver Island, British Columbia. The new species is distinguished by possessing a unique combination of the following diagnostic characters: vitelline fields that extend to the posterior margin of the ventral sucker; a slender, tubular and sinuous seminal vesicle that extends some distance into the hindbody; an unspecialized, protuberant ventral sucker; a genital pore at pharynx level; lobed to deeply multi-lobed testes; a lobed ovary; and an egg size of 68–80 μm × 30–46 μm. A single specimen of Podocotyle Dujardin, 1845 (Digenea: Plagioporinae) is also described from the intestine of an individual Coryphaenoides sp. (Gadiformes: Macrouridae) collected at 2,800 m depth off Oregon. A listing of parasites from the bigfin eelpout as well as observations of parasite diversity within relevant hosts are offered, new host and locality records are noted, and a brief discussion of Pseudopecoelus von Wicklen, 1946 in the deep sea is presented taking note of the low level of host specificity recorded (i.e. spp. of Pseudopecoelus are now known to parasitize deep-water fish from at least 20 piscine families). A new dichotomous key to the 39 recognized species of Pseudopecoelus is introduced.