Revision of the systematics of the Polystomoidinae (Platyhelminthes, Monogenea, Polystomatidae) with redefinition of Polystomoides Ward, 1917 and Uteropolystomoides Tinsley, 2017.

Polystomatids are platyhelminth parasites that infect mainly amphibians and freshwater turtles. For more than seven decades, chelonian polystomes were classified into three genera according to the number of hamuli, i.e. absent for Neopolystoma, one pair for Polystomoidella and two pairs for Polystomoides. Following re-examination of morphological characters, seven new genera were erected the past six years, namely Apaloneotrema, Aussietrema, Fornixtrema, Manotrema, Pleurodirotrema, Uropolystomoides and Uteropolystomoides. However, the polyphyly of Neopolystoma and Polystomoides on the one hand, and the nested position of Uteropolystomoides within a clade encompassing all Neopolystoma and Polystomoides spp. on the other, still raised questions about the validity of these genera. We therefore re-examined several types, paratypes and voucher specimens, and investigated the molecular phylogeny of polystomes sampled from the oral cavity of North American turtles to re-evaluate their systematic status. We show that all Polystomoides Ward, 1917, sensu Du Preez et al., 2022, Neopolystoma Price, 1939, sensu Du Preez et al., 2022 and Uteropolystomoides Tinsley, 2017 species, display vaginae that are peripheral and extend well beyond the intestine. We thus reassign all species of the clade to Polystomoides and propose nine new combinations; however, although Uteropolystomoides is nested within this clade, based on its unique morphological features, we propose to keep it as a valid taxon. Polystomoides as redefined herein groups all polystome species infecting either the oral cavity or the urinary bladder of cryptodires, with peripheral vaginae and with or without two pairs of small hamuli. Uteropolystomoides nelsoni (Du Preez & Van Rooyen 2015), originally described from Pseudemys nelsoni Carr is now regarded as Uteropolystomoides multifalx (Stunkard, 1924) n. comb. infecting three distinct Pseudemys species of North America.

Title: Révision de la systématique des Polystomoidinae (Plathelminthes, Monogenea, Polystomatidae) avec redéfinition des genres Polystomoides Ward, 1917 et Uteropolystomoides Tinsley, 2017. Abstract: Les Polystomatidés sont des plathelminthes parasites qui infestent principalement les amphibiens et les tortues d'eau douce. Pendant plus de sept décennies, les polystomes de chéloniens ont été classés en trois genres selon le nombre d'hamuli, absents pour Neopolystoma, une paire pour Polystomoidella et deux paires pour Polystomoides. Suite au réexamen des caractères morphologiques, sept nouveaux genres ont été érigés ces six dernières années, à savoir Apaloneotrema, Aussietrema, Fornixtrema, Manotrema, Pleurodirotrema, Uropolystomoides et Uteropolystomoides. Cependant, la polyphylie de Neopolystoma et Polystomoides d'une part, et la position imbriquée d'Uteropolystomoides au sein d'un clade englobant toutes les espèces de Neopolystoma et Polystomoides d'autre part, soulèvent encore des questions sur la validité de ces trois genres. Nous avons donc réexaminé plusieurs types, paratypes et vouchers et étudié la phylogénie moléculaire de polystomes prélevés dans la cavité buccale de tortues d'Amérique du Nord pour réévaluer leur statut systématique. Nous montrons que toutes les espèces de Polystomoides Ward, 1917, sensu Du Preez et al., 2022, Neopolystoma Price, 1939, sensu Du Preez et al., 2022 et Uteropolystomoides Tinsley, 2017, présentent des vagins périphériques qui s'étendent bien au-delà de l'intestin. Nous réattribuons ainsi toutes les espèces du clade à Polystomoides et proposons neuf nouvelles combinaisons; cependant, nous proposons de conserver Uteropolystomoides sur la base de ses caractéristiques morphologiques exceptionnelles, bien que son espèce soit imbriquée au sein de ce clade. Polystomoides tel que redéfini ici regroupe toutes les espèces de polystomes infectant soit la cavité buccale, soit la vessie des cryptodires, avec des vagins périphériques, et deux paires de petits hamuli ou sans hamuli. Uteropolystomoides nelsoni (Du Preez & Van Rooyen 2015), l'unique espèce décrite à l'origine à partir de Pseudemys nelsoni Carr est maintenant considérée comme Uteropolystomoides multifalx (Stunkard, 1924) n. comb., qui infecte trois espèces distinctes de Pseudemys d'Amérique du Nord.

Indopolystoma n. gen. (Monogenea, Polystomatidae) with the description of three new species and reassignment of eight known Polystoma species from Asian frogs (Anura, Rhacophoridae).

The polystomes (Monogenea, Polystomatidae) radiated across semi-aquatic tetrapods including all three amphibian orders, freshwater turtles and the hippopotamus. Prior to this study, phylogenetic analyses revealed that the most diverse and widespread genus, Polystoma, was not monophyletic; a lineage comprising four undescribed species from the bladder of Zhangixalus spp. (Rhacophoridae) in Asia occupied a deep phylogenetic position. Regarding vicariance biogeography and molecular dating, the origin of this lineage is correlated with the breakup of Gondwanaland in the Mesozoic period. Based on a Bayesian analysis of four concatenated genes (18S, 28S, COI and 12S) and morphological evidence, one new genus, Indopolystoma n. gen., and three new species, sampled in Japan and China, are described here: Indopolystoma viridi n. sp. from Z. viridis of Japan, Indopolystoma elongatum n. sp. from Z. arboreus of Japan, and Indopolystoma parvum n. sp. from Z. omeimontis of China. Indopolystoma is unique amongst polystome genera infecting anurans by possessing a small haptor relative to the body size, posteriormost marginal hooklet C1 much bigger than hooklets C2-C8 with conspicuous broad blade and guard and a pair of hamuli lacking a deep notch. Eight species of Asian Polystoma, all from rhacophorids, are transferred as Indopolystoma carvirostris (Fan, Li & He, 2008) n. comb., I. hakgalense (Crusz & Ching, 1975) n. comb., I. indicum (Diengdoh & Tandon, 1991) n. comb., I. leucomystax (Zhang & Long, 1987) n. comb., I. mutus (Meng, Song & Ding, 2010) n. comb., I. pingbianensis (Fan, Wang & Li, 2004) n. comb., I. rhacophori (Yamaguti, 1936) n. comb., and I. zuoi (Shen, Wang & Fan, 2013) n. comb.

TITLE: Indopolystoma n. gen. (Monogenea, Polystomatidae) avec description de trois nouvelles espèces et réaffectation de huit espèces connues de Polystoma parasites de grenouilles asiatiques (Anura, Rhacophoridae). ABSTRACT: Les polystomes (Monogenea, Polystomatidae) se sont diversifiés sur des tétrapodes semi-aquatiques, notamment les trois ordres d'amphibiens, les tortues d'eau douce et l'hippopotame. Avant cette étude, des analyses phylogénétiques avaient révélé que le genre le plus diversifié et le plus répandu, Polystoma, n'était pas monophylétique ; une lignée comprenant quatre espèces non décrites de la vessie de Zhangixalus spp. (Rhacophoridae) en Asie occupait une position phylogénétique profonde. En ce qui concerne la biogéographie de vicariance et la datation moléculaire, l'origine de cette lignée est corrélée à l'éclatement du Gondwana au Mésozoïque. D'après une analyse bayésienne de quatre gènes concaténés (18S, 28S, COI et 12S) et des preuves morphologiques, un nouveau genre, Indopolystoma n. gen. et trois nouvelles espèces échantillonnées au Japon et en Chine sont décrites ici : Indopolystoma viridi n. sp. de Z. viridis du Japon, Indopolystoma elongatum n. sp. de Z. arboreus du Japon et Indopolystoma parvum n. sp. de Z. omeimontis de Chine. Indopolystoma est unique parmi les genres de polystomes infectant les anoures. Il possède un hapteur petit par rapport à la taille du corps, un crocheton le plus postérieur C1 beaucoup plus gros que les crochetons C2 à C8, avec lame et garde bien visibles, ainsi qu'une paire d'hamuli dépourvus d'encoche profonde. Huit espèces de polystomes asiatiques, toutes issues de Rhacophoridae, sont transférées comme Indopolystoma carvirostris (Fan, Li & He, 2008) n. comb., I. hakgalense (Crusz et Ching, 1975) n. comb., I. indicum (Diengdoh & Tandon, 1991) n. comb., I. leucomystax (Zhang & Long, 1987) n. comb., I. mutus (Meng, Song & Ding, 2010) n. comb., I. pingbianensis (Fan, Wang et Li, 2004) n. comb., I. rhacophori (Yamaguti, 1936) n. comb. et I. zuoi (Shen, Wang et Fan, 2013) n. comb.

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.

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.

Diplectanids from Mycteroperca spp. (Epinephelidae) in the Mediterranean Sea: Redescriptions of six species from material collected off Tunisia and Libya, proposal for the 'Pseudorhabdosynochus riouxi group', and a taxonomic key.

Diplectanid monogeneans are gill parasites that can infect fish in huge numbers and thus become harmful, especially in maricultured fish. It is therefore useful to have taxonomic tools, such as keys, to identify species. The following diplectanid species from groupers of the Mediterranean Sea were studied: five species of Pseudorhabdosynochus Yamaguti, 1958, including P. riouxi (Oliver, 1986) Kritsky & Beverley-Burton, 1986 from the dusky grouper Mycteroperca marginata, P. enitsuji Neifar & Euzet, 2007, P. bouaini Neifar & Euzet, 2007, P. dolicocolpos Neifar & Euzet, 2007 and P. sinediscus Neifar & Euzet, 2007 from the goldblotch grouper M. costae, and Echinoplectanum echinophallus (Euzet & Oliver, 1965) Justine & Euzet, 2006 from the dusky grouper. New material was obtained from fish collected from off Tunisia and Libya and compared to the type-material and voucher specimens in museum collections. Identifications of fish were confirmed by barcoding of cytochrome c oxidase subunit I (COI) sequences. The sclerotized vagina was considered the most important structure for systematics. The three species P. riouxi, P. bouaini, and P. enitsuji share a common general structure of the sclerotized vagina with a conspicuous spherical secondary chamber. We thus propose the 'Pseudorhabdosynochus riouxi group' to accommodate them. Pseudorhabdosynochus dolicocolpos has an elongate vaginal structure that is completely different from all its congeneric species reported from the Mediterranean Sea, and Pseudorhabdosynochus sinediscus has a sclerotized vagina in which the secondary chamber is not visible, and a haptor without squamodiscs. A taxonomic key to diplectanid species on Mycteroperca spp. in the Mediterranean Sea is proposed; it includes ten species of Pseudorhabdosynochus and one species of Echinoplectanum.

Pseudorhabdosynochus sulamericanus (Monogenea, Diplectanidae), a parasite of deep-sea groupers (Serranidae) occurs transatlantically on three congeneric hosts (Hyporthodus spp.), one from the Mediterranean Sea and two from the western Atlantic.

Little is known of the diversity of the monogenean parasites infesting deep-sea groupers, and there is even less information available about their geographic distributions within the ranges of their hosts. To improve our understanding of these host-parasite relationships we conducted parasitological evaluations of the deep-water Haifa grouper Hyporthodus haifensis from the southern Mediterranean off Tunisia and Libya. We collected more than one species of diplectanid monogeneans from this host, but among these only one dominant species was abundant. This proved to be morphologically very similar to Pseudorhabdosynochus sulamericanus Santos, Buchmann & Gibson, 2000, a species originally described from the congeneric host H. niveatus off Brazil and also recorded from H. niveatus and H. nigritus off Florida. Here, we conducted a morphological comparison between newly collected specimens and those previously deposited in museum collections by other authors. Further, we used COI barcoding to ascertain the specific identity of the three host species to better elucidate the circumstances that might explain the unexpectedly broad distribution of P. sulamericanus. We assigned our specimens from H. haifensis to P. sulamericanus primarily on the basis of morphological characteristics of the sclerotized vagina. We also noted morphological characteristics of eastern and western Atlantic specimens that are not clearly described or not given in previous descriptions and so prepared a redescription of the species. We confirmed, by COI barcoding, that no sister-species relationships were evident among the three hosts of P. sulamericanus. Our observation that P. sulamericanus infects unrelated host species with putatively allopatric distributions was unexpected given the very limited dispersive capabilities and the high degree of host specificity common to members of Pseudorhabdosynochus. This transatlantic distribution raises questions with regard to phylogeography and assumptions about the allopatry of Atlantic grouper species from the Americas and Afro-Eurasia. Here, we propose some hypothetical explanations for our findings.

Species of Pseudorhabdosynochus (Monogenea, Diplectanidae) from Groupers (Mycteroperca spp., Epinephelidae) in the Mediterranean and Eastern Atlantic Ocean, with Special Reference to the 'Beverleyburtonae Group' and Description of Two New Species.

Pseudorhabdosynochus Yamaguti, 1958 is a species-rich diplectanid genus, mainly restricted to the gills of groupers (Epinephelidae) and especially abundant in warm seas. Species from the Mediterranean are not fully documented. Two new and two previously known species from the gills of Mycteroperca spp. (M. costae, M. rubra, and M. marginata) in the Mediterranean and Eastern Atlantic Ocean are described here from new material and slides kept in collections. Identifications of newly collected fish were ascertained by barcoding of cytochrome c oxidase subunit I (COI) sequences. Pseudorhabdosynochus beverleyburtonae (Oliver, 1984) Kritsky & Beverley-Burton, 1986 and P. sosia Neifar & Euzet 2007 are redescribed from type-specimens and new specimens collected off Tunisia and Libya from M. marginata and M. costae, respectively. Pseudorhabdosynochus oliveri n. sp., from M. marginata (type-host) off the Mediterranean coast of France (type-locality), is described from specimens found among voucher specimens of P. beverleyburtonae deposited by Guy Oliver in the collection of the Muséum National d'Histoire Naturelle, Paris. Pseudorhabdosynochus oliveri is distinguished by the shape of its sclerotised vagina; it was not found in the other localities investigated. Pseudorhabdosynochus hayet n. sp. is described from M. rubra (type host) off Senegal (type-locality) and Tunisia. Pseudorhabdosynochus hayet is morphologically similar to P. sosia (type-host: M. costae) but was distinguished by differences in measurements of the vagina and male copulatory organ, different host, and divergent COI sequences. The four species (P. beverleyburtonae, P. sosia, P. oliveri, and P. hayet) share common characteristics such as squamodiscs with 2 innermost circular rows of rodlets and a similar general structure of the sclerotised vagina; we propose to group them into a 'beverleyburtonae group' within Pseudorhabdosynochus.

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.

Pseudorhabdosynochus regius n. sp. (Monogenea, Diplectanidae) from the mottled grouper Mycteroperca rubra (Teleostei) in the Mediterranean Sea and Eastern Atlantic.

Pseudorhabdosynochus regius n. sp. is described from the gills of the mottled grouper Mycteroperca rubra caught off Senegal, Tunisia and Libya (type-locality: off Dakar, Senegal). The species is distinguished from its congeners by the structure of its sclerotised vagina (length 26-35 µm), which exhibits a trumpet in continuity with the primary canal, a straight primary canal, and primary and secondary chambers included in a common sclerotised mass along the primary canal. The species is also characterised by small squamodiscs (length 20-40 µm) with 10-11 rows of rodlets. Its closest relatives (based on the structure of the sclerotised vagina) are species mostly found in the Mediterranean Sea and parasites on species of Mycteroperca. A second species of Pseudorhabdosynochus Yamaguti, 1958 is reported from the same host and localities but not described. A list of diplectanids from groupers in the Mediterranean Sea is provided. We point out that a recent article was not compliant with the new Article 8.5.3 of the International Code of Zoological Nomenclature; for this reason, three species, P. nhatrangensis Dang, Bristow, Schander & Berland, 2013, P. vietnamensis Dang et al., 2013 and P. brunei Dang et al., 2013, are invalid.