Heterocheilus floridensis sp. n. (Nematoda: Heterocheilidae) from the West Indian manatee Trichechus manatus (Trichechidae, Sirenia) in Florida, USA.

Morphological data are used to describe a new nematode species, Heterocheilus floridensis sp. n. (Heterocheilidae) from the digestive tract of the Florida manatee Trichechus manatus latirostris (Harlan) (Trichechidae, Sirenia) from Florida, USA. Examination by light and scanning electron microscopy revealed that the new species differs from the related Heterocheilus tunicatus Diesing, 1839 mainly by having dentigerous ridges on the inner surface of the lips, a median unpaired papilla located anterior to the cloaca, and a considerably larger body size. Sequence data for subunits I and II of mitochondrial cytochrome oxidase gene, 18S small subunit and 28S ribosomal RNA genes were provided for molecular characterisation of the new species. However, the current unavailability of homologous sequence data for congeneric specimens precluded a molecular assessment of the morphological species hypothesis, and ascaridoid phylogenetic hypotheses could not be advanced. Specimens of Heterocheilus sp. collected from the Antillean manatee Trichechus manatus manatus Linnaeus in Puerto Rico, on loan from the US National Museum of Natural History, were morphologically consistent with the new species, so apparently all congeneric nematodes reported from both subspecies of the West Indian manatee Trichechus manatus Linnaeus and previously identified as H. tunicatus belong rather to H. floridensis sp. n. Heterocheilus hagenbecki (Khalil et Vogelsang, 1932) Sprent 1980 is here considered to be a species inquirenda. A key to valid species of Heterocheilus Diesing, 1839 is provided.

Some trematodes including three new species from freshwater fishes of Venezuela.

The present paper comprises a systematic survey of trematodes found in 13 species of freshwater fishes in Venezuela collected in 1992, 1996 and 2001. The following 15 trematode species were recorded: Adults: Genarchella venezuelaensis sp. n., Thometrema dissimilis sp. n., Megacoelium spinicavum Thatcher et Varella, 1981, Doradamphistoma bacuense Thatcher, 1999, Crassicutis cichlasomae Manter, 1936, Parspina carapo Ostrowski de Núñez, Arredonto et Gil de Pertierra, 2011, Phyllodistomoides hoplerythrini sp. n. Larvae (metacercariae): Clinostomatopsis sorbens (Braun, 1899), Clinostomum marginatum (Rudolphi, 1819), C. detruncatum Braun, 1899, Ithyoclinostomum dimorphum (Diesing, 1850), Odhneriotrema microcephala (Travassos, 1922), Tylodelphys sp., Posthodiplostomum sp., Sphincterodiplostomum sp. All these parasites are reported from Venezuela for the first time and many of these findings represent new host records. The new species G. venezuelaensis sp. n., T. dissimilis sp. n. and P. hoplerythrini sp. n. were collected from the accessory respiratory organ of Loricariichthys brunneus (Hancock) (Loricariidae), from the stomach of Hoplerythrinus unitaeniatus (Spix et Agassiz) (Erythrinidae) and from the intestine of H. unitaeniatus, respectively. All parasites are briefly described and illustrated and problems concerning their morphology, taxonomy, hosts and geographical distribution are discussed. Megacoelium spinispecum Thatcher et Varella, 1981 is considered a junior synonym of M. spinicavum Thatcher et Varella, 1981, and Crassicutis opisthoseminis Bravo-Hollis et Arroyo, 1962 as a junior synonym of C. cichlasomae Manter, 1936.

Three new species of Ascarophis van Beneden, 1871 (Nematoda: Cystidicolidae) from deep-sea hydrothermal vent fishes of the Pacific Ocean.

Examinations of some deep-sea hydrothermal vent fishes from the western and eastern regions of the Pacific Ocean revealed the presence of three new species of Ascarophis van Beneden, 1871 (Nematoda: Cystidicolidae), all gastrointestinal parasites, namely: A. justinei n. sp. from Thermarces cerberus Rosenblatt & Cohen (type host) and Thermichthys hollisi Cohen, Rosemblatt & Moser (both Zoarcidae, Perciformes) and A. globuligera n. sp. from T. cerberus from the Northern East Pacific Rise, and A. monofilamentosa n. sp. from Pyrolicus manusanus Machida & Hashimoto (Zoarcidae, Perciformes) from the Manus Basin near Papua New Guinea. Specimens are described and illustrated based on light and scanning electron microscopical examinations. In addition to other morphological differences, all the three new species differ from each other by the structure of eggs: eggs bearing a lateral superficial swelling (A. globuligera n. sp.), eggs with one conspicuously long filament on one pole (A. monofilamentosa n. sp.) and eggs smooth, without any filaments or swellings (A. justinei n. sp.). The egg morphology of the two first-named species is unique within all species of Ascarophis, which indicates that all the three newly described species of Ascarophis are probably endemic to the respective hydrothermal vents as their fish hosts.

Redescriptions of Spinitectus acipenseri and S. micracanthus (Nematoda, Cystidicolidae), with notes on the taxonomy of Spinitectus-like nematodes parasitising North American fishes.

Based on light microscopical and scanning electron microscopical (SEM) examinations, two North American species of Spinitectus Fourment, 1884, S. acipenseri Choudhury & Dick, 1992 and S. micracanthus Christian, 1972 (Nematoda, Cystidicolidae) are redescribed from museum voucher specimens (S. acipenseri) and those newly collected from centrarchid and some other fishes in the Upper San Marcos River in Texas and the Santee River in South Carolina, USA. The first use of SEM to study S. acipenseri, a parasite of lake sturgeon Acipenser fulvescens Rafinesque (Acipenseridae) in Canada, made it possible to describe dorsal and ventral lips, amphids and sublabia, and the presence of a dorsal barb on the right spicule, which was confirmed to be the most characteristic feature of this species. The SEM study of S. micracanthus, a parasite mainly of centrarchids, enabled us to correctly determine the location of the excretory pore in relation to rings of cuticular spines in the male, and to describe the exact structure of the tip of the male tail, sublabia, phasmids and the presence of a median ventral protuberance on the male tail. Some taxonomic problems of North American species of Spinitectus are discussed. Filaria serrata Linton, 1901 is considered a junior synonym of S. oviflagellis Fourment, 1884. To date, there are 13 valid species of Spinitectus parasitising fishes in North America. Keys to species of Spinitectus-like nematodes from fishes in North American waters are provided.

Title: Redescriptions de Spinitectus acipenseri et S. micracanthus (Nematoda, Cystidicolidae), et notes sur la taxonomie des nématodes de type Spinitectus parasitant les poissons nord-américains. Abstract: Deux espèces nord-américaines de Spinitectus Fourment, 1884, S. acipenseri Choudhury & Dick, 1992 et S. micracanthus Christian, 1972 (Nematoda, Cystidicolidae) sont redécrites à partir de spécimens de musée et d'autres nouvellement collectés aux USA dans les rivières Upper San Marcos (Texas) and Santee (Caroline du Sud), avec l'aide de la microscopie optique et électronique à balayage (MEB). L'utilisation pour la première fois du MEB pour étudier S. acipenseri, un parasite de l'esturgeon Acipenser fulvescens Rafinesque (Acipenseridae) au Canada, a permis de décrire les lèvres dorsales and ventrales, les amphides et sublabia, ainsi que la barbe dorsale sur le spicule droit que nous confirmons être le critère le plus caractéristique de cette espèce. L'étude au MEB de S. micracanthus, un parasite principalement de centrarchides, nous a permis de déterminer correctement la place du pore excréteur en relation avec les couronnes d'épines cuticulaires chez le mâle, ainsi que de décrire la structure exacte de l'extrémité caudale du mâle, des sublabia, des phasmides et la présence d'une protubérance médiane et ventrale sur la queue du mâle. Des problèmes taxonomiques sur les espèces nord-américaines de Spinitectus sont discutés. Filaria serrata Linton, 1901 est considéré synonyme plus récent de S. oviflagellis Fourment, 1884. À ce jour, il y a 13 espèces valides de Spinitectus parasites de poissons en Amérique du Nord. Des clés des espèces des nématodes de type Spinitectus provenant des poissons des eaux nord-américaines sont fournies.

Two new species of Dichelyne Jägerskiöld, 1902 (Nematoda: Cucullanidae) parasitising marine fishes in Iraq.

Recent examinations of some marine fishes from off the southern coast of Iraq revealed the presence of two new species of Dichelyne (Dichelyne) Jägerskiöld, 1902 (Nematoda: Cucullanidae), both intestinal parasites, namely: D. (D.) lethrini n. sp. from the smalltooth emperor Lethrinus microdon Valenciennes (Lethrinidae, Acanthuriformes) and D. (D.) iraqiensis n. sp. from the humphead snapper Lutjanus sanguineus (Cuvier) (Lutjanidae, Acanthuriformes). Specimens are described and illustrated based on light and scanning electron microscopical examinations. Dichelyne (D.) lethrini n. sp. is mainly characterised by the length of spicules (522 µm), presence of a dorsal caecum, location of deirids at the level of the posterior end of oesophagus and the post-oesophageal position of the excretory pore, number (10 pairs) and distribution of caudal papillae in the male, and the presence of two minute terminal spines on the female tail tip. Dichelyne (D.) iraqiensis n. sp. differs from the species of the subgenus Dichelyne mainly based on the absence of caudal spines, the presence of a dorsal caecum, the length of spicules (789-884 µm), the location of deirids and the excretory pore approximately at the same level, and the size of eggs (72-78 × 42-51 µm). These new species infecting marine fishes in Iraq represent new geographic records of cucullanids of the subgenus Dichelyne from fishes in marine waters off Iraq.

Two new and one newly recorded gonad-infecting species of Philometra Costa, 1845 (Nematoda: Philometridae) parasitising marine fishes in Iraq.

Specimens of two undescribed and one known gonad-infecting species of Philometra Costa, 1845 (Nematoda: Philometridae) were collected in some marine fishes from off the southern coast of Iraq. Based on light and scanning electron microscopy, the following new species are described: Philometra tayeni n. sp. (males and nongravid females) from ovaries of the purple-spotted bigeye Priacanthus tayenus Richardson (Priacanthidae, Acanthuriformes), and Philometra nibeae n. sp. (males and gravid female) from the ovary of the blotched croaker Nibea maculata (Bloch et Schneider) (Sciaenidae, Acanthuriformes). Philometra tayeni is mainly characterised by a pair of postanal papillae and a V-shaped caudal mound in males and by their body lengths (2.42-2.99 mm), whereas P. nibeae differs from its gonad-infecting congeners parasitising scienids mainly based on the body length of males (2.29-2.49 mm) and their spicules (96-117 µm), absence of a pair of postanal papillae and shape of caudal mound consisting of two parts. Philometra piscaria Moravec & Justine, 2014 (males and nongravid females), a parasite of the orange-spotted grouper Epinephelus coioides (Hamilton) (Epinephelidae, Perciformes), is recorded from the Arabian (= Persian) Gulf for the first time; previously unknown females of this species are described.

Description of Ichthyascaris grandis sp. n., redescription of Raphidascaroides halieutaeae Yin, 1983 and new records of some other raphidascaridid and philometrid nematodes from marine fishes off Java, Indonesia.

Examinations of nematodes collected from some marine fishes off the southwestern coast of Java, Indonesia in 2000 and 2001 revealed the presence of the following six species: ascaridoids Ichthyascaris grandis sp. n. from the intestine of Lophiomus setigerus (Vahl), I. cf. longispicula Li, Liu, Liu et Zhang, 2012 from the intestine of Conger cinereus Rüppel, Ichthyascaris sp. from the body cavity of Lobotes surinamensis (Bloch), and Raphidascaroides halieutaeae Yin, 1983 from the intestine of Halieutaea stellata (Vahl), and philometrids Philometra ivaschkini Parukhin, 1976 from the stomach wall of Trichiurus lepturus Linnaeus and P. psettoditis Moravec, Walter et Yuniar, 2012 from the body cavity (liver) of Psettodes erumei (Bloch et Schneider). Descriptions of these nematodes based on light and scanning electron microscopical studies are provided. The new species I. grandis sp. n. is mainly characterised by large body measurements (males and females up to 41.8 mm and 73.6 mm long, respectively), the length of spicules (0.99-1.05 mm), the tail tip usually without rudimentary spines and by the presence of 44-53 pairs of caudal papillae, eight to twelve of which being postanals. In addition to new data on the morphology of R. halieutaeae and other nematodes recorded, the 11 species of Raphidascaroides Yamaguti, 1941 poorly described from marine fishes in South Asia and reviewed in the monograph of Sood (2017) are considered species inquirendae and incertae sedis.

Description of Pseudocapillaria (Discocapillaria) trilobularis n. sp. (Capillariidae) and redescription of Heliconema alatum (Majumdar, 1965) (Physalopteridae), two nematodes parasitising synbranchiform fishes in India.

One new and one already known species of nematodes are described based on specimens collected from synbranchiform fishes of the River Ganga, India, in 2021 and 2022. Pseudocapillaria (Discocapillaria) trilobularis n. sp. (Capillariidae) from the intestine of cuchia Monopterus cuchia (Hamilton) (Synbranchidae) is mainly characterised by the presence of the large ventral postcloacal lobe in the male, the spicule length 351 µm, eggs size 60-69 × 30-36 µm (with protruding polar plugs) and by the body length (male 10.50 mm, females 11.02-12.44 mm). It is the fourth species of this genus recorded from fishes in India. The species Heliconema alatum (Majumdar, 1965) (Physalopteridae) is resurrected. This nematode is redescribed from specimens collected from the intestine of zig-zag eel Mastacembelus armatus (Lacepède) (Mastacembelidae). The examination by SEM revealed some previously not reported morphological features in this nematode species, e.g., the presence of cephalic papillae or a lateroterminal depression and two inner flat dorsoventral teeth on each pseudolabium. Based on these findings, H. monopteri Moravec, Chaudhary & Singh, 2019 is considered a junior synonym of H. alatum.

Huffmanela cf. huffmani (Nematoda: Trichosomoididae) infecting swim bladder, peritoneum, and gonad of variable platyfish, Xiphophorus variatus (Cyprinodontiformes: Poeciliidae) and eastern mosquitofish, Gambusia holbrooki (Poeciliidae) in Florida; taxonomy, phylogenetic analysis, and pathological changes.

Variable platyfish, Xiphophorus variatus (Meek, 1904) (Cyprinodontiformes: Poeciliidae) and eastern mosquitofish, Gambusia holbrooki Girard, 1859 (Poeciliidae) from earthen ponds in west central Florida were examined for parasitic infections. At necropsy, we observed myriad nematodes (adults and eggs), which we identified as Huffmanela cf. huffmani, infecting the swim bladder, gonad, and visceral peritoneum. Nucleotide sequences (small subunit ribosomal DNA, 18S) of H. cf. huffmani from variable platyfish and eastern mosquitofish were identical; likewise for newly obtained 18S sequences of Huffmanela huffmani Moravec, 1987 from the swim bladder of red breast sunfish, Lepomis auritus (Linnaeus, 1758) (Centrarchiformes: Centrarchidae) and warmouth, Lepomis gulosus (Cuvier, 1829) from the San Marcos River (type locality for Huffmanela huffmani Moravec, 1987), Texas. The sequences of H. huffmani and H. cf. huffmani differed by 7 (1%) nucleotides. Pathological changes comprised proliferation of the tunica externa of the swim bladder in low-intensity infections in addition to inflammation, proliferation, and tissue necrosis of swim bladder, peritoneum, and gonad in high-intensity infections. The lesion was severe, affecting the cellular constituents of the swim bladder wall and reducing the size of the swim bladder lumen; potentially reducing swim bladder physiological efficiency. The present study is the first record of a freshwater species of Huffmanela Moravec, 1987 from beyond the San Marcos River, first record of a species of Huffmanela from a livebearer, first nucleotide sequences and phylogenetic analysis for Huffmanela, and first evidence that an infection by a species of Huffmanela causes pathological changes that could impact organ function.

New data on the morphology and taxonomy of some spiruridan nematodes (Spirurida) parasitising fishes in Jammu and Kashmir, India.

Adult specimens of five little-known species of spiruridan nematodes (Spirurida) were collected during occasional examinations of some fishes from the Poonch River in Jammu and Kashmir, India: Procamallanus (Spirocamallanus) bilaspurensis Gupta et Duggal, 1973 in Mastacembelus armatus (Lacépède) (Mastacembelidae, Synbranchiformes), Rhabdochona (Rhabdochona) indica Moravec, Scholz, Ash et Kar, 2010 in Crossocheilus latius (Hamilton) (Cyprinidae, Cypriniformes), Rhabdochona (Rhabdochona) turkestanica (Skryabin, 1917) in Schizothorax richardsonii (Gray) (Cyprinidae, Cypriniformes) and both Rhabdochona (Rhabdochona) hospeti Thapar, 1950 and Rhabdochona (Globochona) cf. chodukini Osmanov, 1957 in Tor putitora (Hamilton) (Cyprinidae, Cypriniformes); besides these, unidentifiable physalopterid larvae were recorded from M. armatus and T. putitora. Their detailed light and electron microscopical studies revealed some taxonomically important, previously not observed features and made possible their redescription. Fourth-stage larvae of P. (S.) bilaspurensis and R. (R.) turkestanica are described for the first time. The latter is resurrected as an independent species. The following are considered to be species inquirendae: a total of nine poorly described species of Rhabdochona Railliet, 1916 from T. putitora in Balochistan, Pakistan, all listed in the monograph of Kakar et al. (2011), plus an additional 15 species of the genus reported from cyprinids and a catfish in the same region (Balochistan) by the same authors. Also three congeneric species from India (R. nemacheili Rautela et Malhotra, 1982, R. putitora Kaur et Khera, 1991 and R. tori Gupta et Srivastava, 1982) and one from Pakistan (R. charsaddiensis Siddiqi et Khattak, 1984) should be considered as species inquirendae due to their poor descriptions. The names of Rhabdochona putitori Anjum, 2013, R. indusi Soofi, Birmani et Dharejo, 2017 and R. sindhicus Soofi, Birmani, Dharejo, Abbasi et Ghachal, 2020 are invalid according to the International Code of Zoological Nomenclature.

Five species of Philometra Costa, 1845 (Nematoda: Philometridae) newly recorded from marine fishes in Iraq, including the description of P. arabiensis sp. n. from the ovary of the shrimp scad Alepes djedaba (Carangidae).

Recent examinations of some marine fishes from off the southern coast of Iraq revealed the presence of five species of Philometra Costa, 1845 (Nematoda: Philometridae): Philometra arabiensis sp. n. (males and females) from the ovary of the shrimp scad Alepes djedaba (Forsskål) (Carangidae, Carangiformes), Philometra psettoditis Moravec, Walter et Yuniar, 2012 (females) from the body cavity of the Indian halibut Psettodes erumei (Bloch et Schneider) (Psettodidae, Pleuronectiformes), Philometra terapontis Moravec, Gopalakrishnan, Rajkumar, Saravanakumar et Kaliyamoorthy, 2011 (female) from the ovary of the jarbua terapon Terapon jarbua (Forsskål) (Terapontidae, Centrarchiformes), Philometra sp. (females) from the ovary of the Arabian blackspot threadfin Polydactylus mullani (Hora) (Polynemidae, Carangariformes) and Philometra sp. 2 of Moravec et al. (2016a) (females) from the ovary and body cavity of the bartail flathead Platycephalus indicus (Linnaeus) (Platycephalidae, Perciformes). Philometra arabiensis sp. n. is mainly characterised by the length of spicules (198-243 µm) and gubernaculum (75-99 µm), the gubernaculum/spicule length ratio (1 : 2.33-2.79), the structure of the gubernaculum distal portion and the male caudal end, and the body length of males (1.86-2.73 mm). The present findings of P. psettoditis and P. terapontis in fishes of the Arabian Gulf represent new geographical records for these parasites.

Phylogenetic relationships of philometrid nematodes (Philometridae Baylis & Daubney, 1926) inferred from 18S rRNA, with molecular characterisation of recently described species.

Nematodes of the family Philometridae Baylis & Daubney, 1926 (Dracunculoidea Stiles, 1907) are generally poorly known, and there are many taxonomic issues within the family. Philometrids are parasites of fish and are found in various locations throughout the host, including within the subcutaneous tissues and musculature, the abdominal cavity and gonads; vast sexual dimorphism often means the males are not collected, leading to many species being described solely on female characteristics. Although there have been a number of studies utilising molecular data, the vast majority of species are yet to be sequenced. This study undertook genetic sequencing of 15 recently described species of philometrids across 4 genera, many of which were from specimens collected from waters off Australia. All of the sequences obtained were closely related with representatives of the family Philometridae. Species were found to be distributed in the phylogenetic trees within 4 clades based on a combination of site of infection within the host and host habitat. Family of host and geographical location was not as important for position within the trees. Clade A contained philometrids collected from the abdominal cavities and head tissues of South American freshwater fish. Clade B contained philometrids primarily from the abdominal cavities of freshwater European cyprinids. Clade C contained philometrids primarily from the ovaries of marine fish. Clade D contained philometrids from the body tissues of marine and freshwater fish. The potential co-evolutionary patterns between philometrids and their fish hosts are highlighted as an area of future research. This research also highlighted the importance of correct identification of any sequenced specimen.

Echinocephalus inserratus sp. n. (Nematoda: Gnathostomatidae) from the stingray Pastinachus ater (Dasyatidae) and new records of congeneric and some other nematode larvae from teleost fishes off New Caledonia.

Based on light and electron microscopical studies, a new nematode parasite, Echinocephalus inserratus sp. n. (Spirurida: Gnathostomatidae), is described from the spiral valve of the broad cowtail stingray Pastinachus ater (Macleay) (Dasyatidae, Myliobatiformes) from off New Caledonia. The new species is morphologically and biometrically most similar to Echinocephalus overstreeti Deardorff et Ko, 1983, differing from it mainly in the absence of serrations on the posterior parts of pseudolabia and on interlabia, and in having a longer gubernaculum (150-299 µm long). Morphologically unidentifiable, mostly encapsulated larvae of Echinocephalus spp. were recorded from the following six species of teleost fishes collected in New Caledonian waters, serving as paratenic hosts: Perciformes: Acanthopagrus berda (Forsskål) (Sparidae) and Nemipterus furcosus (Valenciennes) (Nemipteridae); Tetraodontiformes: Abalistes stellatus (Anonymous), Pseudobalistes fuscus (Bloch et Schneider) (both Balistidae), Lagocephalus sceleratus (Gmelin) (Tetraodontidae) and Aluterus monoceros (Linnaeus) (Monacanthidae). Co-parasitising larvae of Ascarophis sp. and Hysterothylacium sp. were also collected from P. fuscus. All these findings represent new host and geographical records. A key to valid species of Echinocephalus Molin, 1858 is provided.

Records of two gonad-infecting species of Philometra (Nematoda: Philometridae) from marine fishes off Iraq, including the description of Philometra parabrevicollis n. sp. from the bigeye snapper Lutjanus lutjanus Bloch (Pisces, Lutjanidae).

Recent examinations of some marine fishes from off the southern coast of Iraq revealed the presence of two species of Philometra Costa, 1845 (Nematoda: Philometridae): P. parabrevicollis n. sp. (males and subgravid and nongravid females) from the ovary of the bigeye snapper Lutjanus lutjanus Bloch (Perciformes, Lutjanidae) and Philometra sp. (subgravid females) from the ovary of the bartail flathead Platycephalus indicus (Linnaeus) (Perciformes, Platycephalidae). Specimens of species are described and illustrated based on light and scanning electron microscopical examinations. Philometra parabrevicollis n. sp. is mainly characterised by the length of spicules (267-285 µm) and gubernaculum (159-168 µm), the gubernaculum/spicule length ratio (1:1.64-1.76), the structure of the gubernaculum distal tip and of the male caudal end, and the body length of males (4.03-4.90 mm). The description of this new species again confirms a high degree of host specificity of gonad-infecting species of Philometra in congeneric lutjanid hosts. Although Philometra sp. parasitising P. indicus in Iraqi waters was previously recorded, its subgravid females are described for the first time. A key to gonad-infecting species of Philometra parasitic in fishes of the family Lutjanidae is provided.

Two species of philometrid nematodes (Philometridae) newly recorded from marine fishes off South Australia, including Philometra inconveniens n. sp. from Hyporhamphus melanochir (Valenciennes) (Hemiramphidae).

Recent examinations of some marine fishes from off the coast of South Australia revealed the presence of two species of Philometra Costa, 1845 (Nematoda: Philometridae): P. inconveniens n. sp. from the ovary (males) and body cavity (subgravid female) of the southern garfish Hyporhamphus melanochir (Valenciennes) (Beloniformes, Hemiramphidae) and Philometra sp. (gravid and subgravid females) from the body cavity of the Australian barracuda Sphyraena novaehollandiae Günther (Perciformes, Sphyraenidae) (new host and geographical records). Specimens of species are described and illustrated based on light and scanning electron microscopical examinations. Philometra inconveniens n. sp. differs from the most similar species P. longa Moravec, Barton & Shamsi, 2021, a parasite of the body cavity of the congeneric host off eastern Australia, mainly by a different structure of the gubernaculum (absence of dorsal barbs and presence of lateral extensions on its distal portion). This indicates a high degree of host specificity of these nematodes in co-occuring congeneric hosts.

Morphological and genetic description of two new species of philometrid nematodes (Philometridae) parasitic in needlefishes (Belonidae) from estuaries of Florida, USA.

Two new species of philometrid nematodes (Philometridae) from needlefishes (Belonidae) in Florida are described based on morphological and genetic characteristics: Philometra aequispiculata sp. n. (males and females) collected from the ovary of Strongylura marina (Walbaum) (type host) and Strongylura notata (Poey), and Philometra notatae sp. n. (females) from the swimbladder of S. notata. Both species are described and illustrated based on light and scanning electron microscopical examinations. Morphologically, P. aequispiculata sp. n. differs from all congeners mainly in the unique structure of the distal tip of the gubernaculum, whereas P. notatae sp. n. is mainly characterised by the presence of eight markedly large cephalic papillae of the outer circle in gravid and subgravid females, the body length of the gravid female (54 mm) and by the absence of caudal projections. Molecular characterisation of the new species was assessed from phylogenetic analysis of mitochondrial cytochrome c oxidase I (COI) and SSU rRNA small-subunit ribosomal RNA (SSU) sequences among closely related philometrids by way of Bayesian inference. Phylogenetic reconstructions based on COI and SSU sequences show each of the new species comprise discrete ancestor-descendent lineages.

Philometra longa n. sp. (Nematoda: Philometridae), a new parasite from the abdominal cavity of the eastern sea garfish Hyporhamphus australis (Hemiramphidae, Beloniformes) off Australia.

A new nematode species, Philometra longa n. sp. (Philometridae), is described from male and female specimens collected from the body cavity of the marine fish, Hyporhamphus australis (Steindachner) (Hemirhamphidae, Beloniformes) from off the south-eastern coast of Australia. Based on examination by light and scanning electron microscopy, the new species differs from those parasitising other beloniform hosts mainly in the body length (4.69 mm), the length of spicules (141 µm) and the structure of the caudal end and the distal tip of gubernaculum in the male, and in the conspicuously long body (455-560 mm) of the gravid female. Philometra longa n. sp. is the first species of philometrids described from fishes of the family Hemiramphidae. It is the 26th nominal species of philometrids and the 19th species of Philometra so far recorded from Australian marine and brackish waters. Re-examined museum specimens of Philometra sp. from Hyporhamphus melanochir (Valenciennes) off Tasmania, as well as those previously reported from the same host species off the Australian coast, were found to be identical with P. longa sp. n.

Redescription of Ascarophis distorta Fusco et Overstreet, 1978 (Nematoda, Cystidicolidae) from the stomach of some butterflyfishes off New Caledonia.

PURPOSE: The nematode Ascarophis distorta Fusco et Overstreet, 1978 (Cystidicolidae), originally described from the butterflyfish Chaetodon paucifasciatus Ahl (Perciformes, Chaetodontidae) in the Red Sea, was established based solely on the light microscopical (LM) examination of specimens. However, the present taxonomy of cystidicolid nematodes is mostly based on details of the cephalic structures properly visible only with the use of scanning electron microscopy (SEM). METHODS: Helminthological examinations of some marine fishes from coral reefs off New Caledonia, South Pacific, carried out in the years 2003-2007, revealed the presence of A. distorta in two Chaetodon spp. and thus enabled its redescription. The nematode specimens were studied with the use of both LM and SEM. RESULTS: The specimens of A. distorta were obtained from the stomach of the threadfin butterflyfish Chaetodon auriga Forsskål and the vagabond butterflyfish Chaetodon vagabundus Linnaeus. This is just the second record of this parasite since its description 43 years ago. SEM, used in this species for the first time, revealed some taxonomically important, previously unreported or insufficiently described morphological features, such as details in the cephalic structure, the shape of deirids, structure of the distal tip of the left spicule, or the exact number and distribution of male caudal papillae. The finding of A. distorta in C. auriga and C. vagabundus off New Caledonia represents new host and geographical records. The examination of 39 specimens of butterflyfishes from off New Caledonia, belonging to 14 Chaetodon spp. and 3 Heniochus spp., revealed that the nematode was only present in the 2 fish species listed above. CONCLUSIONS: This parasite seems to be host-specific to only certain species of butterflyfishes (Chaetodon spp.), and is probably widespread in the Indo-Pacific region, as well as its hosts.

Some Spirurid Nematodes (Spirurida) from Freshwater and Brackish-Water Fishes in Okinawa Prefecture, Japan, with Descriptions of Two New Species.

PURPOSE: Despite the fact that Okinawa Prefecture represents a very interesting subtropical region of Japan, its fauna of nematodes parasitizing fishes is still little-known. Therefore, new data are needed to recognize the species composition of these parasites in this zoogeographically remarkable region. METHODS: Helminthological examinations of some freshwater and brackish-water fishes in Okinawa Prefecture carried out in the years 2010, 2016 and 2018, revealed two new and four insufficiently known species of spirurid nematodes (Spirurida), all gastrointestinal parasites. These were studied with the use of light and scanning electron microscopy. RESULTS: All nematode species recorded are described: Rhabdochonidae: Rhabdochona honshuensis Moravec et Nagasawa, 1989 from Glossogobius celebius (Valenciennes) (Gobiidae, Perciformes) (new host), Rhabdochona iriomotensis sp. nov. from Ophieleotris sp. (Eleotridae, Perciformes) and Rhabdochona sp. (only females) from Eleotris acanthopoma Bleeker and E. fusca (Forster) (both Eleotridae, Perciformes); Cystidicolidae: Spinitectus mirabilis sp. nov. from Kuhlia rupestris (Lacepède) (Kuhliidae, Perciformes) and Spinitectus sp. larvae from E. acanthopoma; and Camallanidae: Procamallanus (Spirocamallanus) sp. (fourth-stage larva) from Yongeichthys criniger (Valenciennes) (Gobiidae, Perciformes). Rhabdochona iriomotensis sp. nov. is very similar to R. honshuensis, but differs from it in the presence of well-developed ventral precloacal ridges. Spinitectus mirabilis sp. nov. differs from its congeners and all other cystidicolids in having eggs provided with both lateral swellings and polar filaments. CONCLUSIONS: In addition to the discovery of two new nematode species, Rhabdochona iriomotensis sp. nov. and Spinitectus mirabilis sp. nov., the findings of all other species represent new host and geographical records. Rhabdochona denudata honshuensis Moravec et Nagasawa, 1989 is elevated to the level of an independent species R. honshuensis.

Description of Raphidascaris (Ichthyascaris) multipapillata sp. nov., Redescription of Hysterothylacium simile Li et al., 2013 and New Records of Some Other Ascaridoid and Seuratoid Nematodes from Marine Fishes in Japan.

PURPOSE: Many nematode species parasitizing marine fishes were reported from Japanese waters. However, considering the wealth of fish species in this zoogeographically interesting region and the host specificity of nematodes, the number of hitherto recorded fish nematodes probably represents only a very small part of the potential Japanese fauna of these organisms. Therefore, new data are needed to recognise the species composition of these parasites in this region. METHODS: Helminthological examinations of some marine fishes from off Japan, carried out in the years 2005-2017, revealed one new and five insufficiently known species of ascaridoid and seuratoid nematodes. These were studied with the use of light and scanning electron microscopy. RESULTS: All six nematode species recorded are described: Anisakidae: Raphidascaris (Ichthyascaris) multipapillata sp. nov. (male and females) from the intestine of Labracoglossa argenteiventris Peters (Kyphosidae) in the Sea of Japan, Raphidascaris (Ichthyascaris) sp. (third-stage larvae) probably from the digestive tract of Seriola dumerili (Risso) and S. rivoliana Valenciennes (both Carangidae) in the western North Pacific Ocean off Ishigaki-jima Island, Okinawa Prefecture, Hysterothylacium simile Li et al., 2013 (males and females) from the stomach of Lateolabrax japonicus (Cuvier) (Lateolabracidae) in the Sea of Japan, Hysterothylacium sp. 1 (female) from the pyloric caeca of Jaydia lineata (Temminck et Schlegel) (Apogonidae) in the Seto Inland Sea, Hysterothylacium sp. 2 (third- and fourth-stage larvae) from the intestine and mesentery of Etelis coruscans Valenciennes (Lutjanidae) and Pseudorhombus pentophthalmus Günther (Paralichthyidae) in the western North Pacific Ocean off Ishigaki-jima Island, Okinawa Prefecture and the Seto Inland Sea, respectively; and Cucullanidae: Cucullanus sp. (female) from the intestine of Semicossyphus reticulatus (Valenciennes) (Labridae) in the Seto Inland Sea. Raphidascaris (I.) multipapillata sp. n. differs from congeners mainly in the high number (79) of pairs of caudal papillae, spicules 402 µm long and in the structure of the male and female tail tips. Hysterothylacium simile is redescribed, being recorded from off Japan for the first time. CONCLUSIONS: In addition to the discovery of the new nematode species R. (I.) multipapillata sp. nov. and a redescription of H. simile providing some new morphological data of this parasite, the findings of all other species represent new host and geographical records. The present study extends the knowledge of the species composition and host-parasite relationships of nematodes parasitizing marine fishes.