AbstractPodocotyle bathyhelminthos n. sp. (Opecoelidae: Plagioporinae) is described from the cusk-eel, Luciobrotula corethromycter Cohen, 1964 (Ophidiiformes: Ophidiidae), collected at depths of 622-1,280 m in the northern Gulf of Mexico and Caribbean Sea off Colombia. The new species is distinguished by possessing a combination of the following features: an elongate oval body shape, a sucker width ratio of 1:1.4-1.9, deeply lobed and irregularly-shaped testes, a cirrus-sac that extends just in to the hindbody, a trilobed ovary and vitellarium that extend to the ventral sucker level. Several unique features in P. bathyhelminthos n. sp. were not present in all, or almost all, recognized species of Podocotyle including a conspicuous deep cleft at the posterior end of the worm, a small transverse ridge on the ventral surface immediately anterior to the ventral sucker, uterine loops extending ventral to the caeca and, at times, lateral to the caeca, a thick-walled metraterm extending 1/3 to 1/2 the length of the cirrus-sac and P. bathyhelminthos n. sp. parasitizes a deep water piscine host. Podocotyle etheostomae Aliff, 1973 is declared a nomen nudum. A brief discussion of Podocotyle Dujardin, 1845 in deep waters is presented, and a gastropod, caridean shrimp and cusk-eel are hypothesized as hosts in the life cycle of P. bathyhelminthos n. sp. in the deep sea.
Nectonemertes mirabilis (Nemertea: Hoplonemertea: Pelagica) from deep waters of the Gulf of Mexico, first sighting of a pelagic nemertean in the gulf
