Occurrence of Podocotyle Dujardin, 1845 (Opecoelidae, Podocotylinae) in three species of deep-sea macrourids from the Gulf of Mexico and Caribbean Sea with an updated key to species and host-parasite checklist.

Podocotyle pearsei Manter, 1934 is documented from the intestine of Vaillant's grenadier, Bathygadus melanobranchus Vaillant (Macrouridae: Bathygadinae), collected from the northeastern and western Gulf of Mexico from 783-841 m depth. The finding of P. pearsei in B. melanobranchus represents the first originally published report of this genus from this host and the fifth documented host species for P. pearsei. We report three unidentified species of Podocotyle, represented by one individual each, from the intestine of the western Atlantic grenadier, Nezumia atlantica (Parr) (Macrouridae: Macrourinae), and from Bathygadus favosus Goode Bean (Macrouridae: Bathygadinae) found at 637 m, 710 m and 1,143 m depths in the northeastern Gulf of Mexico off Florida and from the Caribbean Sea off Colombia. We provide a checklist of the parasites known from the three macrourid species relevant to this study, comment on the biogeography of the five species of Podocotyle now known from the deep sea and discuss the low host specificity observed across this genus. The high number of fish hosts for Podocotyle (i.e. type hosts include at least 22 piscine families) encompassing a wide phylogenetic diversity and diet makes it unlikely that members of a single genus could evolve such a broad array of life histories (i.e. utilize dissimilar intermediate hosts), and we predict in the future that Podocotyle will be taxonomically divided up. Morphological and especially molecular work is needed for Podocotyle as well as for other digenean genera known to inhabit the deep sea. Podocotyle sp. 1 2 represent the first originally published reports of this genus from N. atlantica while Podocotyle sp. 3 represents the first report of this genus from B. favosus. Podocotyle koshari Nagaty, 1973 is declared a species inquirenda, and a dichotomous key to the 27 species of Podocotyle we recognize is provided.

Podocotyle nimoyi n. sp. (Digenea: Opecoelidae: Plagioporinae) and a re-description of Podocotyle pearsei Manter, 1934 from five species of deep-sea macrourids from the Gulf of Mexico and Caribbean Sea.

Two rare species of Podocotyle Dujardin, 1845 (Digenea: Opecoelidae) parasitizing five macrourid species inhabiting the deep waters of the northeastern Gulf of Mexico and Caribbean Sea off Panama are described. Podocotyle nimoyi n. sp. was found in the intestine of the pugnose grenadier, Sphagemacrurus grenadae (Parr), and the common Atlantic grenadier, Nezumia aequalis (Günther) (Gadiformes: Macrouridae), at depths of 534-995 m in the Northeast Gulf of Mexico off Florida and represents the fifth species of Podocotyle endemic to the deep sea. Podocotyle pearsei Manter, 1934, was re-described from the intestine of the bullseye grenadier, Bathygadus macrops Goode & Bean, the doublethread grenadier, Gadomus arcuatus (Goode & Bean), and the western softhead grenadier, Malacocephalus occidentalis Goode & Bean (Gadiformes: Macrouridae), collected from 591-728 m depths in the Northeast Gulf of Mexico off Florida and the Caribbean Sea off Panama. The following new host records are established: P. nimoyi n. sp. is the third parasite species known from S. grenadae and the first digenean species reported from this host; P. nimoyi n. sp. is the first reported species of Podocotyle parasitizing N. aequalis; and this is the first report of P. pearsei or any representative of the genus Podocotyle infecting B. macrops, G. arcuatus and M. occidentalis. A listing of all digenean parasites previously reported from the five macrourid species examined herein is given and some observations are made about Podocotyle in the deep sea.

Macrourimegatrema gadoma n. sp. (Digenea: Opecoelidae) from the doublethread grenadier Gadomus arcuatus (Goode & Bean) (Macrouridae) in the Gulf of Mexico and Caribbean Sea.

Macrourimegatrema gadoma n. sp. (Digenea: Opecoelidae: Plagioporinae) is described from the pyloric caeca and intestine of the doublethread grenadier Gadomus arcuatus (Goode & Bean) (Macrouridae) collected from the northeastern Gulf of Mexico and off Venezuela. The new species differs from Macrourimegatrema brayi Blend, Dronen & Armstrong, 2004, the type and only species in the genus, in the distribution of the vitelline follicles and gonads, a larger body size, and the presence of highly-folded caeca with numerous outpocketings or pouches. It is suggested that species of Macrourimegatrema Blend, Dronen & Armstrong, 2004 probably infect their piscine hosts through the ingestion of a benthopelagic crustacean.