Towards resolving the problematic status of the digenean genus Astiotrema Looss, 1900: Taxa excluded from Astiotrema (sensu stricto) with special reference to plagiorchioid genera closely related to the restricted concept of Astiotrema.

The restricted concept of Astiotrema Looss, 1900 has been revised to include only eight species and various representative synonyms. However, several remaining taxa of Astiotrema (sensu lato) still need more inspection and scrutiny to determine their correct taxonomic position. Following a comprehensive review, four new genera are erected to accommodate some taxa excluded from Astiotrema (sensu stricto), three of which are closely related to this restricted concept of Astiotrema.

A NEW SPECIES OF PROSOGONOTREMA (SCLERODISTOMIDAE: PROSOGONOTREMATINAE) FROM THE FLATHEAD GREY MULLET, MUGIL CEPHALUS LINNAEUS (MUGILIFORMES: MUGILIDAE), FROM THE ARABIAN GULF OFF IRAQ.

Prosogonotrema iraqiense n. sp. (Sclerodistomidae: Prosogonotrematinae) is described in the flathead grey mullet, Mugil cephalus Linnaeus (Mugiliformes: Mugilidae), collected from the Arabian Gulf off Iraq during June and October 2019.

Reconsideration of the species assigned to Faustula Poche, 1926 (Digenea: Microphalloidea) with the proposal of five new genera in the Faustulidae Poche, 1926.

The assignment of species to Faustula Poche, 1926 (Faustulidae Poche, 1926) is reconsidered with the proposal of Gangafaustula n. gen. to accommodate Gangafaustula makundai (Agarwal Verma, 1981) n.

Towards resolving the problematic status of the digenean genus Astiotrema Looss, 1900: An updated concept and revision of species composition for Astiotrema (sensu stricto).

Species of Astiotrema Looss, 1900 (sensu lato) infect a wide range of fishes, amphibians and reptilians. They also possess a considerably wide spectrum of morphological features. Several species were recognized for variable, confusing, overlapping and unspecialized morphological characters rather than for unique distinguishing features, causing continuing dispute around the validity of several species.

Unusual opecoelids from Red Sea triggerfishes with special reference to characteristic concepts of the Opistholebetinae Fukui, 1929 (Digenea: Opecoelidae).

Three digeneans belonging to the Opecoelidae are reported and described from triggerfishes (Tetraodontiformes: Balistidae) collected in the northern Red Sea off Egypt. Both Macvicaria longicirrata (Manter, 1963) Aken-Ova, Cribb Bray, 2008 and Neopycnadena tendu (Bray Justine, 2007) n. comb.

A new genus and species of Anchitrematidae Mehra, 1935 (Digenea: Gorgoderoidea) in a freshwater fish from the River Nile at Qena, Egypt with amendation of the family.

Museum specimens of a previously unknown species of the Anchitrematidae from a freshwater fish collected from the River Nile at Qena, Egypt were examined. This species is somewhat similar to species of Anchitrema, but was found to have a thick, continuous, shelf-like rim around the periphery of the ventral aspect of the distome, the lateral aspect of the forebody was composed of large internal patches of lightly vacuolated, somewhat glandular cells that formed pad-like structures (pelops-like structures), and it possessed a uterine seminal receptacle; characteristics that previously have not been found in any species in the family. Species currently assigned to Anchitrema or Mujibia (the only two genera in the family) are known only from reptiles and mammals and no species has previously been reported from a freshwater fish.

Gaharitrema droneni n. gen., n. sp. (Digenea: Zoogonidae) from the Pudgy Cuskeel, Spectrunculus grandis (Ophidiiformes: Ophidiidae), from Deep Waters Off Oregon, with Updated Keys to Zoogonid Subfamilies and Genera.

Gaharitrema droneni n. gen., n.

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.

Re-examination of the phylogenetic relationships within the Gyliauchenidae Fukui, 1929 (Digenea) based on morphological and molecular evidence with a proposal for Paragyliaucheninae n. subfam. and a description of Flagellotrema convolutum Ozaki, 1936.

Flagellotrema convolutum Ozaki, 1936 was found parasitising the intestine of two new host fish species, the Indian sail-fin surgeonfish, Zebrasoma desjardinii (Bennett) (Acanthuridae), and the Picasso triggerfish, Rhinecanthus assasi (Forsskål) (Balistidae), from the northern Red Sea off Egypt. Another description of this species is provided with detailed morphological observations made of the genital systems. Using newly acquired molecular data from the D1-D3 regions of 28S rDNA, the phylogenetic relationships of subfamilies and genera within the Gyliauchenidae Fukui, 1929 are elucidated with morphological support.

Revision of the Megaperidae Manter, 1934 n. comb. (Syn. Apocreadiidae Skrjabin, 1942) including a reorganization of the Schistorchiinae Yamaguti, 1942.

Modified and/or new keys to the four subfamilies now recognized within the Megaperidae Manter, 1934 n. comb. (Syn.

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.

Pelopscreadium aegyptense n. gen., n. sp. and Pelopscreadium spongiosum (Bray & Cribb, 1998) n. comb., (Digenea: Lepocreadiidae), each from disjunct populations of the Yellow boxfish, Ostracion cubicus Linnaeus (Ostraciidae).

Bianium spongiosum Bray & Cribb, 1998 (Lepocreadiidae), described from the yellow boxfish, Ostracion cubicus Linnaeus (Ostraciidae), off Lizard Island, Queensland, Australia, possesses a combination of the following three morphological features which distinguishes it from all the other species currently assigned to the genus: (1) large internal patches of large cells forming sponge-like pads we have termed "pelops"("pelop" sing.) laterally in the forebody extending from near the anterior extremity to about the level of the intestinal bifurcation rather than possessing a scoop; (2) ceca that reach to near the posterior extremity where they end blindly without ani; and (3) a vitellarium which is present laterally but not dorsal to the ceca. Based on this we propose the erection of Pelopscreadium n.

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.

Updated keys to the genera in the subfamilies of Cyclocoelidae Stossich, 1902, including a reconsideration of species assignments, species keys and the proposal of a new genus in Szidatitreminae Dronen, 2007.

Keys to the six subfamilies, 22 genera within subfamilies and 128 species recognized within the Cyclocoelidae are provided. Lists of species in each genus are provided, along with taxonomic summaries that include type host, type locality, additional hosts, additional localities, previously proposed synonyms, and remarks for each species. The following synonymies are proposed: Cyclocoelum mutabile (Zeder, 1800)-Syn.

Re-evaluation of Tellervotrema katadara (Kuramochi, 2001) Kuramochi, 2009 (Opecoelidae: Plagioporinae) and supplementary morphological data for T. beringi (Mamaev, 1965) Gibson & Bray, 1982 with new host and locality.

The trematode genus Tellervotrema Gibson & Bray, 1982 was erected for Podocotyle-like species that parasitize archybenthal macrourid fishes (also known as grenadiers or rattails) and that possess no vitelline follicles dorsal to the ceca but do have a symmetrical pair of isolated groups of vitelline follicles in the posterior forebody. Tellervotrema katadara (Kuramochi, 2001) Kuramochi, 2009 is resurrected as a valid species based on an examination and re-description of holotype and paratype specimens collected from the intestine of the bathygadine macrourid Gadomus colletti Jordan & Gilbert from 518-582 m depth in Tosa Bay, off the Pacific coast of southern Japan. Tellervotrema beringi (Mamaev, 1965) Gibson & Bray, 1982 is re-described from specimens originally identified as T.

Description of a new species of Podocotyle Dujardin, 1845 (Digenea: Opecoelidae: Plagioporinae) from the cusk-eel, Luciobrotula corethromycter Cohen, 1964 (Ophidiiformes: Ophidiidae), from the Gulf of Mexico and Caribbean Sea.

Podocotyle 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.

Keys to the species of Neolebouria Gibson, 1976 (Digenea: Opecoelidae: Plagioporinae), with a redescription of Neolebouria truncata (Linton, 1940).

Three keys to the species of Neolebouria Gibson, 1976, representing three body types, are provided based on the location of the genital pore relative to the intestinal bifurcation. These are: the lanceolata body type, where the genital pore is clearly prebifurcal; the diacopae body type, where the genital pore is located at or near the level of the intestinal bifurcation; and the maorum body type, where the genital pore is clearly postbifurcal. Fifteen species were assigned to the lanceolata body type; eight species to the diacopae body type; and four species to the maorum body type.

A new species of Neolebouria Gibson, 1976 (Opecoelidae: Plagioporinae) from the whitecheek monocle bream, Scolopsis vosmeri (Perciformes: Nemipteridae), from the Panjim coast at Goa, with a checklist of parasites previously reported from this fish.

Neolebouria capoori n. sp. (Opecoelidae: Plagioporinae) is described from the whitecheek monocle bream, Scolopsis vosmeri (Bloch) (Perciformes: Nemipteridae) from the Panjim coast on the central west coast of India at Goa.

New species of Prodistomum Linton, 1910 (Digenea: Lepocreadiidae) from the longtail bass, Hemanthias leptus (Ginsburg, 1952) in the Bay of Campeche, Gulf of Mexico.

Prodistomum lichtenfelsi n. sp. (Digenea: Lepocreadiidae) is described; it was obtained from the intestine of the longtail bass, Hemanthias leptus (Ginsburg), collected from the Bay of Campeche in the Gulf of Mexico.

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.

Karyakartia egyptensis n. sp. (Digenea: Lepocreadiidae) from the Jarbua terapon, Terapon jarbua (Forsskål) (Perciformes: Terapontidae), from the Red Sea and emendation of Karyakartia.

Karyakartia egyptensis n. sp. (Digenea: Lepocreadiidae: Lepocreadiinae) is described from the intestine of the Jarbua terapon, Terapon jarbua (Forsskål), collected from the Red Sea off the coast of Hurghada, Egypt.

A new genus and species of cyclocoelid from the black-necked stilt, Himantopus mexicanus (Recurvirostridae), from Galveston, Texas.

Two black-necked stilts, Himantopus mexicanus (Recurvirostridae), from the Texas Gulf coast, died while in the care of bird rehabilitators and were found to be infected with Neoallopyge americanensis n. gen., n.

Clestobothrium gibsoni n. sp. (Cestoda: Bothriocephalidae) from the bullseye grenadier Bathygadus macrops Goode & Bean (Macrouridae) in the Gulf of Mexico.

Clestobothrium gibsoni n. sp. is described from the intestine of the bullseye grenadier Bathygadus macrops (Macrouridae) collected in the northeastern Gulf of Mexico.