Molecular phylogenetic relationship between Philometroides tahieli (Nematoda, Philometridae) and other philometrids from South America.

In South America, the family Philometridae is represented by several genera and species. In particular, Philometra and Philometroides are the most speciose genera. In Argentina, only Philometroides tahieli has been reported so far. The main objective of this study was to analyze the phylogenetic relationship between Ps. tahieli and other South American philometrids using molecular data. The molecular analysis was performed using a female specimen of Ps. tahieli found on the opercular muscle of a juvenile Micropogonias furnieri from brackish waters in Argentina. Phylogenetic relationships were studied based on partial sequences of the 18S rDNA and 28S rDNA genes. In the 18S rDNA tree, Ps. tahieli was mainly grouped with other Philometroides from freshwater hosts from China, sharing the site of infection (head tissues or muscles). In the 28S rDNA tree, obtained with fewer sequences, Ps. tahieli is related species from subcutaneous tissues of head. This study contributes with information on philometrids and confirms the presence of different lineages among South American species, with Ps. tahieli representing a new one. Further studies on South American species using more molecular markers and new morphological characters will improve our knowledge of philometrid biodiversity and phylogeny.

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.

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.

New records of Philometra pellucida (Jägerskiöld, 1893) (Nematoda: Philometridae) from the body cavity of Arothron mappa (Lesson) and Arothron nigropunctatus (Bloch et Schneider) reared in aquariums, with synonymisation of Philometra robusta Moravec, Möller et Heeger, 1992.

We encountered two cases of infection with large female nematodes of the genus Philometra Costa, 1845 in the body cavity of a map puffer Arothron mappa (Lesson) caught off Okinawa, Japan, and a blackspotted puffer Arothron nigropunctatus (Bloch et Schneider) caught off Queensland, Australia, both reared in aquariums in Japan. No morphological difference was observed between the nematodes from A. mappa and A. nigropunctatus. We identified the nematodes as Philometra pellucida (Jägerskiöld, 1893) based on their morphology. The sequences of the nematodes from both hosts were identical to each other (1,643 bp) and formed a clade with other 17 nematodes belonging to the genera Philometra and Philometroides Yamaguti, 1935 with high bootstrap value (bp = 100). It is the first time that the genetic data on P. pellucida are provided. Philometra robusta Moravec, Möller et Heeger, 1992 is synonymised with the former species.

New records of Philometra spp. (Nematoda: Philometridae) from marine perciform fishes off Florida, USA, including descriptions of two new species.

Recent examinations of marine perciform fishes from off the Florida coast in the Gulf of Mexico and Straits of Florida, USA, revealed the presence of the following six species of Philometra Costa, 1845 (Nematoda: Philometridae): P. haemulontis sp. n. (males and females) from the ovary of Haemulon plumierii (Lacepède) (type host) and H. aurolineatum Cuvier (both Haemulidae); Philometra synagridis Moravec, Bakenhaster et Fajer-Ávila, 2014 (males and females) from the ovary and testes of Lutjanus synagris (Linnaeus) (Lutjanidae); P. margolisi Moravec, Vidal-Martínez et Aguirre-Macedo, 1995 (male) from the ovary of Hyporthodus nigritus (Holbrook) (Serranidae) (new host record; probably a paradefinitive host); P. andersoni sp. n. (male) from the ovary of H. nigritus; Philometra sp. 1 (male) from the ovary of Rhomboplites aurorubens (Cuvier) (Lutjanidae); and Philometra sp. 2 (females) from the subcutaneous tissue of the anterior-most head sinuses of Hyporthodus niveatus (Valenciennes) (Serranidae). Specimens of species are described and illustrated based on light and (except for Philometra sp. 1) scanning electron microscopical examinations. Philometra haemulontis sp. n. differs from all congeners in the unique structure of the gubernaculum, whereas P. andersoni sp. n. can be differentiated from other gonad-infecting congeners parasitising the Serranidae by a combination of morphological features. Females of P. synagridis are described for the first time. Gravid females of Philometra sp. 2 are similar to those of P. morii Moravec, Bakenhaster et Fajer-Ávila, 2010, a subcutaneous parasite of Epinephelus morio (Valenciennes) (Serranidae) in the Gulf of Mexico.

New records of philometrids (Nematoda: Philometridae) from marine fishes off Japan, including description of Philometra kidakoi sp. n. and Congerinema japonicum gen. et sp. n.

Occasional examinations of some marine fishes in Japan revealed, in addition to other parasites, the following eight species of philometrid nematodes (Philometridae) (all females only): Philometra kidakoi sp. n. from the ovary of Gymnothorax kidako (Temminck et Schlegel) (Muraenidae); Philometra pinnicola (Yamaguti, 1935) from the operculum of Epinephelus akaara (Temminck et Schlegel) (Serranidae); Philometra sebastisci Yamaguti, 1941 from the ovary of Sebastes cheni Barsukov (Scorpaenidae) (new host); Philometra madai Quiazon, Yoshinaga et Ogawa, 2008 from the ovary of Acanthopagrus schlegelii (Bleeker) (Sparidae) (new host); Philometra isaki Quiazon, Yoshinaga et Ogawa, 2008 from the ovary of Parapristipoma trilineatum (Thunberg) (Haemulidae); Philometra sp. from the ovary of Synanceia verrucosa Bloch et Schneider (Synanceiidae); Congerinema japonicum gen. et sp. n. from the subcutaneous tissue of Conger myriaster (Brevoort) (Congridae); and Clavinema mariae (Layman, 1930) from the operculum of Acentrogobius pflaumii (Bleeker) (Gobiidae). Specimens of all species are described based on light and scanning electron microscopical examinations. Philometra kidakoi sp. n. is the first gonad-infecting philometrid from the Muraenidae. The new monotypic genus Congerinema gen. n. is characterised by the unique net-like cuticular ornamentation on the female body. Clavinema mariae is considered to be a complex of several cryptic species and a need of the discovery of conspecific males is stressed (this also concerns other philometrid species with unknown males). At present, the fauna of philometrid nematodes parasitising marine fishes in Japanese waters is represented by 22 nominal species belonging to four genera.

Description of Two New Species of Philometra Costa, 1845 (Nematoda: Philometridae) from Marine Fishes off Japan, with Notes on Philometroides seriolae (Yamaguti, 1935).

PURPOSE: Philometrid nematodes (Philometridae) represent a group of more than 200 species parasitic in the body cavity and various body tissues of fishes. Due to morphological and biological peculiarities, the majority of them are known only by their large females. Generally, the fauna of these parasites remains little known. METHODS: Occasional helminthological examinations of three species of marine fishes in Japan revealed two new and one insufficiently known species of these tissue-dwelling parasites. These were studied with the use of light and scanning electron microscopy. RESULTS: All three nematode species are described. Philometra ostorhinchi sp. nov. (males and females) from the ovary of Ostorhinchus semilineatus (Temminck et Schlegel) (Apogonidae, Perciformes) is characterized mainly by the lengths and structure of spicules and the gubernaculum (spicules 108-120 µm long, length of the gubernaculum 78-87 µm); it is the only species of philometrids parasitic in a fish belonging to the Apogonidae. The gravid females of Philometra tenuis sp. nov. (only females available) from the head subcutaneous tissues of Conger myriaster (Brevoort) (Congridae, Anguilliformes) differ from congeners mainly in an unusual shape of the anterior oesophageal bulb. Some new data on the morphology of an insufficiently known species Philometroides seriolae (Ishii, 1931), collected from the body musculature of Seriola quinqueradiata Temminck et Schlegel (Carangidae, Perciformes), are provided; the number and arrangement of cephalic papillae in subgravid females of P. seriolae were found to be similar to those in females of the majority of other philometrid species. CONCLUSIONS: The present study extends the knowledge of the species composition of philometrids parasitizing marine fishes and of the morphology of P. seriolae, the type species of Philometroides Yamaguti, 1935.

First description of the male and subgravid female of Philometra serranellicabrillae Janiszewska, 1949 (Nematoda: Philometridae), a gonad-infecting parasite of the comber Serranus cabrilla (Linnaeus) (Serranidae) off Tunisia.

The male and subgravid female of Philometra serranellicabrillae Janiszewska, 1949 (Philometridae) collected from the gonads of Serranus cabrilla (Linnaeus) (Serranidae) off Tunisia are described for the first time based on light and scanning electron microscopical studies. The male of this nematode can be separated from other congeneric gonad-infecting nominal species in the structure and shape of the gubernaculum (e.g. absence of a dorsal protuberance and a median smooth field). The shape of the male posterior region is unique in that it bears a pair of big circular papillae posterior to the cloacal opening, which is also present in other Philometra spp. from serranids, i.e. P. indica Moravec & Manoharan, 2014, P. inexpectata Moravec, Chaabane, Justine & Neifar, 2016 and P. jordanoi (López-Neyra, 1951) Yamaguti, 1961. Moreover, P. serranellicabrillae differs from its congeners in other fish families from the Mediterranean Sea, in the length of spicules and gubernaculum.

First description of the male of Philometroides acreanensis and phylogenetic assessment of Philometridae (Nematoda: Dracunculoidea) suggest instability of some taxa.

The male of Philometroides acreanensis, parasitic in the anterior intestine external wall of the freshwater catfish Pimelodus blochii, from the Brazilian Amazon, is described for the first time. Additional data on the morphology of females is given. The new morphological data strengthened the validity of the species as well as its first genetic characterization, using three nuclear genetic markers (18S and 28S of the rDNA and ITS1-58S-ITS2), confirmed the high genetic resemblance of male and female specimens. Philometroides acreanensis shows morphological features of the generic diagnosis of Neophilometroides, Alinema, Philometra and Philometroides. Phylogenetic analyses using sequences of the18S rDNA from representatives of Dracunculoidea confirmed the validity of P. acreanensis and its close relatedness with Alinema rather than with other genera. The validity of Philonemidae was confirmed, as was the monophyly of Philometridae and Clavinema. However, Dentiphilometra, Philometra and Philometroides appear not to be monophyletic. Host taxa, habitat and geographic occurrence seem to have some relationship with the evolutionary traits of certain phylogenetic assemblages of philometrids, which were highly supported in the phylogentic reconstructions. Even though interesting aspects of the phylogeny and taxonomy of Philometridae came to light, further integrative approaches should be used that include additional genetic markers, due to the loose boundaries between some genera as observed here.

Philometra barbata n. sp. (Nematoda: Philometridae) from the red mullet Mullus barbatus (Perciformes, Mullidae) off Tunisia.

Helminthological examinations of the red mullet Mullus barbatus (Linnaeus) (Mullidae) from the Gulf of Hammamet, off Tunisia, revealed the presence of one undescribed gonad-infecting nematode species, Philometra barbata n. sp. (Philometridae). The new species as other congeneric species is mainly characterized by the shape of the caudal mound, the distribution of the caudal papillae and the shape of the gubernaculum with the presence of a dorsal protuberance consisting of two dorsolateral lamellar parts separated from each other by a smooth median field in the male. The new species differs from its gonadinfecting congeners in the body length of male, the length of spicules and gubernaculum. This is the second nominal species of Philometra reported from fishes of the family Mullidae and the 14th from the Mediterranean Sea.

Redescription of Philometra pellucida (Jägerskiöld, 1893) (Nematoda: Philometridae) parasitic in the abdominal cavity of the blackspotted puffer Arothron nigropunctatus (Bloch & Schneider) (Teleostei: Tetraodontidae) off Australia and Japan.

The nematode Philometra pellucida (Jägerskiöld, 1893) (Philometridae) is redescribed from female specimens obtained from the abdominal cavity of the marine tetraodontiform fish (blackspotted puffer) Arothron nigropunctatus (Bloch & Schneider) (Tetraodontidae) off Lizard Island, Australia and off Okinawa, Japan. This is just the second record of this parasite since its description 125 years ago. Light and scanning electron microscopical examination of these nematodes revealed some taxonomically important, previously unreported morphological features, such as the number and arrangement of cephalic papillae, presence of the oesophageal cell nucleus and the size of first-stage larvae in the uterus. This new report of P. pellucida infecting A. nigropunctatus off Australia and Japan represents new host and geographical records. A key to the species of Philometra Costa, 1845 parasitising tetraodontiform fishes is provided.

Pseudodelphis eleginopsis n. sp. (Nematoda: Guyanemidae), a new tissue-dwelling parasite of the Patagonian blennie Eleginops maclovinus (Cuvier) (Perciformes: Eleginopsidae) in Argentina, with notes on related forms.

Based on light and scanning electron microscopical studies, a new nematode parasite, Pseudodelphis eleginopsis n. sp. (Dracunculoidea: Guyanemidae), is described from tissues behind the gills of the Patagonian blennie Eleginops maclovinus (Cuvier) (Perciformes: Eleginopsidae) off the Atlantic coast (San Matías and San José Gulfs) of Patagonia, Argentina. The new species is mainly characterised by the length of the body (males 10-13 mm, larvigerous females 31-59 mm), the number (14) and arrangement of cephalic papillae, the absence of a buccal capsule, the muscular to glandular oesophagus length ratio (1:3-4) of larvigerous females, the length of the spicules (48-63 µm) and the number (7 pairs) and arrangement of the caudal papillae in the male. Pseudodelphis eleginopsis n. sp. is the first species of this genus described from a marine fish in the Atlantic Ocean and the first known dracunculoid parasitising the fish host belonging to the family Eleginopsidae. As revealed by the examination of very young females of the new species, the female genital tract of Pseudodelphis spp. is monodelphic. The genus Syngnathinema Moravec, Spangenberg & Frasca, 2001 is considered a junior synonym of Pseudodelphis Adamson & Roth, 1990 and, consequently, S. californiense and S. chitwoodi are transferred to Pseudodelphis as P. californiensis (Moravec, Spangenberg & Frasca, 2001) n. comb. and P. chitwoodi (Moravec & Kuchta, 2013) n. comb., respectively. Two dracunculoid species, Pseudodelphis limnicola Brugni & Viozzi, 2006 and the previously established Philonema percichthydis Moravec, Urawa & Coria, 1997, both described from the same freshwater host species, Percichthys trucha (Valenciennes), in the same region (Patagonia), are considered to be identical; therefore, the valid name of this species is Pseudodelphis percichthydis n. comb. and P. limnicola becomes its junior synonym. A key to the species of Pseudodelphis is provided.

New records of philometrids (Nematoda: Philometridae) from marine fishes off Australia, including description of four new species and erection of Digitiphilometroides gen. n.

The following six species of the Philometridae (Nematoda: Dracunculoidea) were recorded from marine fishes off the northern coast of Australia in 2015 and 2016: Philometra arafurensis sp. n. and Philometra papillicaudata sp. n. from the ovary and the tissue behind the gills, respectively, of the emperor red snapper Lutjanus sebae (Cuvier); Philometra mawsonae sp. n. and Dentiphilometra malabarici sp. n. from the ovary and the tissue behind the gills, respectively, of the Malabar blood snapper Lutjanus malabaricus (Bloch et Schneider); Philometra sp. from the ovary of the goldbanded jobfish Pristipomoides multidens (Day) (Perciformes: all Lutjanidae); and Digitiphilometroides marinus (Moravec et de Buron, 2009) comb. n. from the body cavity of the cobia Rachycentron canadum (Linnaeus) (Perciformes: Rachycentridae). Digitiphilometroides gen. n. is established based on the presence of unique digital cuticular ornamentations on the female body. New gonad-infecting species, P. arafurensis and P. mawsonae, are characterised mainly by the length of spicules (252-264 µm and 351-435 µm, respectively) and the structure of the gubernaculum, whereas P. papillicaudata is characterised mainly by the body length (70 mm) of gravid female, extent of the oesophageal gland, size of caudal projections and the location in the host. Dentiphilometra malabarici differs from congeners mainly in the arrangement of circumoral teeth (in a single row), extent of the oesophageal gland and the absence of sclerotised teeth or protuberances on the oesophageal lobes in the mouth. Digitiphilometroides marinus has not previously been reported from fishes in Australian waters.

Redescription of Philometra filiformis (Stossich, 1896) (Nematoda: Philometridae), a gonad-infecting parasite of the common pandora Pagellus erythrinus (Linnaeus) (Sparidae) in the Mediterranean Sea, including new taxonomic features revealed by SEM.

The insufficiently known nematode species Philometra filiformis (Stossich, 1896) (Philometridae) is redescribed based on light and scanning electron microscopical (SEM) examinations of specimens collected from the ovaries of the type-host, the common pandora Pagellus erythrinus (Linnaeus) (Perciformes, Sparidae), from off the Mediterranean coast of Tunisia. The male of this species was studied with SEM for the first time, which revealed some new, taxonomically important morphological features. The male posterior end has a caudal mound consisting of two lateral parts widely separated dorsally from each other, four pairs of small adanal papillae, a pair of large but moderately developed papillae located posterior to the cloacal aperture and a pair of small phasmids. The distal end of the gubernaculum is unique among all but one gonad-infecting species of Philometra Costa, 1845 by the chevron-shaped dorsal lamellar structures forming a median longitudinal range. Philometra filiformis is for the first time reported from Tunisian coastal waters, being the seventh philometrid species so far recorded from marine fishes off Tunisia.

Micropleura huchzermeyeri n. sp. (Camallanida: Dracunculoidea: Micropleuridae) from the Nile crocodile, Crocodylus niloticus Laurenti (Reptilia: Crocodylidae), in South Africa.

Micropleura huchzermeyeri n. sp. (Camallanida: Dracunculoidea: Micropleuridae) is described from the peritoneal cavity of Crocodylus niloticus Laurenti (Reptilia: Crocodylidae), based on a detailed study of its morphology using light and scanning electron microscopy. The new species is compared with its congeners, M. australiensis Moravec, Kay & Hobbs, 2004, M. vazi Travassos, 1933 and M. vivipara von Linstow, 1906 from crocodilians, and with M. indica Khera, 1951 from chelonian hosts. It can be distinguished from these by the length of its spicules, which are longer than in all described species and a combination of characters, including the presence of prominent lateral caudal papillae on the level of the cloaca in males, the presence of conspicuous phasmids on the female tail, the pre-equatorial position of the vulva and the length of the first-stage larvae. Micropleura huchzermeyeri n. sp. is further characterised by having 14 cephalic papillae in both sexes and ten pairs of caudal papillae in males. This is the first report of a representative of the genus Micropleura von Linstow, 1906 from a crocodilian in the Afrotropical region. Micropleura helicospicula Dey Sarkar, 2003 is considered a species incertae sedis.

Species of Philometra (Nematoda, Philometridae) from fishes off the Mediterranean coast of Africa, with a description of Philometra rara n. sp. from Hyporthodus haifensis and a molecular analysis of Philometra saltatrix from Pomatomus saltatrix.

Two gonad-infecting species of Philometra Costa, 1845 (Nematoda, Philometridae) were recorded for the first time from marine perciform fishes off Tunisia and Libya: Philometra rara n. sp. from the rare, deep-water Haifa grouper Hyporthodus haifensis (Serranidae) off Libya and Philometra saltatrix Ramachandran, 1973 from the bluefish Pomatomus saltatrix (Pomatomidae) off Tunisia. Identification of both fish species was confirmed by molecular barcoding. Light and scanning electron microscope studies of Ph. rara n. sp. showed that it is characterized by the length of spicules (216-219 µm) and the gubernaculum (90-93 µm), the gubernaculum/spicules length ratio (1:2.32-2.43), and mainly by the shape and structure of the distal end of the gubernaculum (shovel-shaped with a wide median smooth field in dorsal view), appearing as having a dorsal protuberance in lateral view, and by the structure of the male caudal mound (dorsally interrupted); large subgravid females (70-137 mm long) are characterized by the presence of four oval submedian cephalic elevations, each of them bearing a pair of cephalic papillae of the outer circle. The finding of Ph. saltatrix off Tunisia confirms that this species is widespread throughout the Mediterranean region. A molecular analysis of our Ph. saltatrix specimens and other available philometrid cytochrome c oxidase 1 (COI) sequences showed that most species have robust clades. Sequences of Ph. saltatrix from Tunisia diverge from Ph. saltatrix from Brazil and the USA, suggesting that speciation is currently occurring between populations from both sides of the Atlantic Ocean.

New tissue-dwelling species of Philometra Costa, 1845 and Philometroides Yamaguti, 1935 (Nematoda: Philometridae) from marine perciform fishes off the northern coast of Australia.

Based on light and scanning electron microscopical studies, three new species of philometrids (Nematoda: Philometridae) are described from females collected in marine perciform fishes off the northern coast of Australia: Philometra gracilis n. sp. and Philometroides branchiarum n. sp. from tissues behind the gills and gill arches, respectively, of the John's snapper Lutjanus johnii (Bloch) (Lutjanidae), and Philometroides stomachicus n. sp. from the stomach wall of the blackspotted croaker Protonibea diacanthus (Lacépède) (Sciaenidae). Philometra gracilis differs from other congeners described from the Lutjanidae mainly in the presence of large caudal projections, short gravid females (28-42 mm long), the oesophageal gland extending anteriorly far anterior to the level of the nerve-ring, the site in the host and its geographical distribution. Philometroides branchiarum is mainly characterised by the possession of conspicuous, sclerotised oesophageal teeth and very short gravid females (6-8 mm long), whereas P. stomachicus can be differentiated by the body length of gravid females (85-90 mm), the length of the oesophagus (2.67 mm) representing 3% of the body length, the maximum width/body length ratio of gravid females (1:28-32), cuticular bosses densely distributed throughout the body but absent from the oesophageal region, the absence of oesophageal teeth and caudal projections, and the site in the host. The presence of P. gracilis and P. branchiarum in L. johnii and that of P. stomachicus in P. diacanthus confirm the possibility of the coexistence of more philometrid species in different sites within sympatric specimens of one and the same definitive host.

Two gonad-infecting species of Philometra (Nematoda: Philometridae) from groupers (Serranidae) off Tunisia, with a key to Philometra species infecting serranid gonads.

Based on light and scanning electron microscopical studies of nematode specimens (males and mature females) collected from the ovary of groupers (Serranidae, Perciformes) in the Mediterranean Sea off Tunisia (near Tunis and Sfax), two gonad-infecting species of Philometra Costa, 1845 (Nematoda, Philometridae) are reported: Philometra inexpectata n. sp. from the mottled grouper Mycteroperca rubra and P. jordanoi (López-Neyra, 1951) from the dusky grouper Epinephelus marginatus. Identification of both fish species was confirmed by molecular barcoding. The new species is mainly characterized by the length of equally long spicules (147-165 µm), the gubernaculum (63-93 µm long) bearing at the tip two dorsolateral lamellar parts separated from each other by a smooth median field, a V-shaped mound on the male caudal extremity, the presence of a pair of large caudal papillae located posterior to the cloaca and by the body length of the males (1.97-2.43 mm). Philometra inexpectata n. sp. is the fifth known gonad-infecting philometrid species parasitizing serranid fishes in the Mediterranean region. The males of P. jordanoi were examined by scanning electron microscopy for the first time; this detailed study revealed some new taxonomically important morphological features, such as the number and arrangement of cephalic and caudal papillae, presence of amphids and phasmids and mainly the lamellate structures at the posterior end of the gubernaculum. A key to gonad-infecting species of Philometra parasitic in serranid fishes is provided.

Descriptions of Philometra aenei n. sp. and P. tunisiensis n. sp. (Nematoda: Philometridae) from Epinephelus spp. off Tunisia confirm a high degree of host specificity of gonad-infecting species of Philometra Costa, 1845 in groupers (Serranidae).

Based on light and electron microscopical studies of males and mature females, two new gonad-infecting species of Philometra Costa, 1845 (Nematoda: Philometridae) are described from the ovary of groupers, Epinephelus spp. (Perciformes; Serranidae), in the Mediterranean Sea off Tunisia (near Sfax): Philometra aenei n. sp. from the white grouper E. aeneus (Geoffroy Saint-Hilaire) and P. tunisiensis n. sp. from the goldblotch grouper E. costae (Steindachner). Identification of both fish hosts was confirmed by barcoding of the infected fish specimens. Philometra aenei is mainly characterised by the length of conspicuously distended spicules (108-123 µm), the presence of a distinct dorsal barb at the middle region of the gubernaculum and a distinct protuberance consisting of two dorsolateral lamellar parts separated from each other by a smooth median field at its distal tip, a V-shaped mound on the male caudal extremity and by the body length of the males (2.34-3.05 mm). The male of this species was found to possess minute deirids in the cervical region, which is quite exceptional within the Philometridae. Philometra tunisiensis is distinguished from other gonad-infecting congeneric species parasitising serranids by the length of the needle-like spicules and gubernaculum (201-219 and 78-87 µm, respectively), spicule length representing 9-11% of body length, the gubernaculum/spicules length ratio of 1:2.52-2.77, the length of oesophagus in the male comprising 15-16% of the body length, the absence of a dorsal protuberance on the distal lamellar part of the gubernaculum and a pair of large papillae posterior to the cloaca, a dorsally interrupted mound on the male caudal extremity and the body length of the male (2.01-2.42 mm). The presence of three morphologically very different species of Philometra in congeneric hosts in the Mediterranean Sea confirms a high degree of host specificity of these gonad-infecting nematodes parasitising groupers.

New records of philometrids (Nematoda: Philometridae) from marine fishes off Iraq, with the erection of two new species and the first description of the male of Philometroides eleutheronemae Moravec & Manoharan, 2013.

Based on light and scanning electron microscopical studies, the following five species of philometrid nematodes (Nematoda: Philometridae) are described from marine fishes from off Basrah, southern Iraq (Arabian Gulf): Philometra iraqiensis n. sp. (females) from the abdominal cavity and ovary of the Klunzinger's mullet Liza klunzingeri (Day) (Mugiliformes: Mugilidae), P. megalaspidis n. sp. (females) from the ovary of the torpedo scad Megalaspis cordyla (Linnaeus) (Perciformes: Carangidae), Philometra sp. 1 (females) from the ovary of the greater lizardfish Saurida tumbil (Bloch) (Aulopiformes: Synodontidae), Philometra sp. 2 (females) from the ovary of the bartail flathead Platycephalus indicus (Linnaeus) (Scorpaeniformes: Platycephalidae) and Philometroides eleutheronemae Moravec & Manoharan, 2013 (male and females) from the ovary of the fourfinger threadfin Eleutheronema tetradactylum (Shaw) (Perciformes: Polynemidae). The new species are characterised mainly by the body length, the length and structure of the oesophagus and caudal end and by the family of their fish hosts. The male and the gravid female of P. eleutheronemae are described for the first time; the finding of this species in Iraqi waters represents the first record of this nematode in the region of the Arabian (=Persian) Gulf.