PREVALENCE OF OPECOELID TREMATODES (TREMATODA: DIGENEA: OPECOELIDAE) IN THE WOOLLY SCULPIN CLINOCOTTUS ANALIS FROM THE PACIFIC COAST OF THE BAJA CALIFORNIA PENINSULA.

Prevalence values for 3 digenean species of the family Opecoelidae were calculated during a half-year period from 20 individuals per month of the fish species Clinocottus analis, collected from an intertidal environment of Baja California, Mexico. Trematode species recovered were Opecoelus adsphaericus, Opecoelus cameroni, and Opecoelus pacificus. Of these, only O. adsphaericus was present throughout the study, whereas O. pacificus and O. cameroni were recorded for 1 or 2 mo, respectively, exhibiting relatively low prevalence values. The decrease in prevalence of O. adsphaericus coincides with the appearance of O. pacificus and O. cameroni; these last 2 species were found only in the largest hosts, and their presence represents new records for Mexican marine fauna.

Phylogenetic position of Ancyrocephalus (sensu lato) curtus Achmerov, 1952 (Monopisthocotylea, Dactylogyridae), a parasite of fish Perccottus glenii Dybowski, 1877(Gobiiformes: Odontobutidae).

The genus Ancyrocephalus sensu lato is a large assemblage of species of dactylogyrid monopisthocotyleans without clear taxonomic boundaries. Despite an urgent need for revision, only three representatives of this taxon have been molecularly characterised so far. We found specimens of Ancyrocephalus curtus, a previously non-genotyped species, in gills of Perccottus glenii caught in the River Syumnyur, Amur Basin, Russia. The aim of this study was to assess the phylogenetic position of this parasite using partial sequences of 28S rRNA gene. In the phylogenetic tree, A. curtus appeared as a sister taxon to the dactylogyrine genus Gobioecetes. The new molecular evidence supports the hypothesis about the non-monophyletic status of Ancyrocephalus sensu lato.

One Health monitoring reveals invasive freshwater snail species, new records, and undescribed parasite diversity in Zimbabwe.

BACKGROUND: Snail-borne trematodes afflict humans, livestock, and wildlife. Recognizing their zoonotic potential and possible hybridization, a One Health approach is essential for effective control. Given the dearth of knowledge on African trematodes, this study aimed to map snail and trematode diversity, focusing on (i) characterizing gastropod snail species and their trematode parasites, (ii) determining infection rates of snail species as intermediate hosts for medically, veterinary, and ecologically significant trematodes, and (iii) comparing their diversity across endemic regions. METHODS: A cross-sectional study conducted in 2021 in Chiredzi and Wedza districts in Zimbabwe, known for high human schistosomiasis prevalence, involved malacological surveys at 56 sites. Trematode infections in snails were detected through shedding experiments and multiplex rapid diagnostic polymerase chain reactions (RD-PCRs). Morphological and molecular analyses were employed to identify snail and trematode species. RESULTS: Among 3209 collected snail specimens, 11 species were identified, including schistosome and fasciolid competent snail species. We report for the first time the invasive exotic snail Tarebia granifera in Zimbabwe, which was highly abundant, mainly in Chiredzi, occurring at 29 out of 35 sites. Shedding experiments on 1303 snails revealed a 2.24% infection rate, with 15 trematode species identified through molecular genotyping. Five species were exclusive to Chiredzi: Bolbophorus sp., Schistosoma mansoni, Schistosoma mattheei, Calicophoron sp., and Uvulifer sp. Eight were exclusive to Wedza, including Trichobilharzia sp., Stephanoprora amurensis, Spirorchid sp., and Echinostoma sp. as well as an unidentified species of the Plagiorchioidea superfamily. One species, Tylodelphys mashonensis, was common to both regions. The RD-PCR screening of 976 non-shedding snails indicated a 35.7% trematode infection rate, including the presence of schistosomes (1.1%) Fasciola nyanzae (0.6%). In Chiredzi, Radix natalensis had the highest trematode infection prevalence (33.3%), while in Wedza, R. natalensis (55.4%) and Bulinus tropicus (53.2%) had the highest infection prevalence. CONCLUSIONS: Our xenomonitoring approach unveiled 15 trematode species, including nine new records in Zimbabwe. Schistosoma mansoni persists in the study region despite six mass deworming rounds. The high snail and parasite diversity, including the presence of exotic snail species that can impact endemic species and biomedically important trematodes, underscores the need for increased monitoring.

Untangling the Derogenes varicus species complex in Scandinavian waters and the Arctic: description of Derogenes abba n. sp. (Trematoda, Derogenidae) from Hippoglossoides platessoides and new host records for D. varicus (Müller, 1784) sensu stricto.

Several studies have shown that the euryxenic trematode Derogenes varicus (Müller, 1784) represents a species complex. Four lineages have been designated (DV1-4) with the DV1 clade corresponding to D. varicus sensu stricto. Herein, we investigate newly collected specimens of D. varicus sensu lato from Scandinavian and Arctic waters using integrative taxonomy. The trematodes were collected from Melanogrammus aeglefinus, Eutrigla gurnardus, Trachinus draco, and Merluccius merluccius off the Atlantic coast of Sweden and from Hippoglossoides platessoides from Arctic Svalbard. 28S sequences of derogenids from Sweden were identical to D. varicus sensu stricto, confirming its euryxeny. The 28S sequences of Derogenes sp. from H. platessoides were identical to Derogenes DV2 and differed from D. varicus sensu stricto by 3% and from Derogenes DV3 by 2%. The 28S sequence divergences of Derogenes sp. from H. platessoides with D. ruber and D. lacustris were 3 and 10%, respectively. ITS2 and cox1 divergences between Derogenes sp. from H. platessoides and other Derogenes species/lineages were at levels of interspecific differences. The species from H. platessoides is described here as D. abba n. sp. We also examined the type material of Progonus muelleri (Levinsen, 1881), the type and only species of the genus Progonus, with redescription and designations of paralectotypes. Based on specimens from Theodor Odhner's collections at the Swedish Museum of Natural History, SMNH, Stockholm, we provide novel morphological and anatomical data for D. varicus sensu lato species complex. Lastly, we investigated Arthur Looss's "lost collection" of Trematodes at the SMNH and characterised a putative species Derogenes sp. "limula".

Title: Démêler le complexe d'espèces Derogenes varicus dans les eaux scandinaves et arctiques : description de Derogenes abba n. sp. (Trematoda, Derogenidae) parasite d'Hippoglossoides platessoides et nouveaux signalements d'hôtes pour D. varicus (Müller, 1784) sensu stricto. Abstract: Plusieurs études ont montré que le trématode euryxene Derogenes varicus (Müller, 1784) représente un complexe d'espèces. Quatre lignées ont été désignées (DV1­4), le clade DV1 correspondant à D. varicus sensu stricto. Ici, nous étudions des spécimens nouvellement collectés de D. varicus sensu lato dans les eaux scandinaves et arctiques en utilisant la taxonomie intégrative. Les trématodes ont été collectés de Melanogrammus aeglefinus, Eutrigla gurnardus, Trachinus draco et Merluccius merluccius au large de la côte atlantique de la Suède et d'Hippoglossoides platessoides du Svalbard arctique. Les séquences 28S des Derogenidae de Suède étaient identiques à D. varicus sensu stricto, confirmant son euryxénie. Les séquences 28S de Derogenes sp. de H. platessoides étaient identiques à Derogenes DV2 et différaient de D. varicus sensu stricto par 3% et de Derogenes DV3 par 2%. Les divergences des séquence 28S de Derogenes sp. de H. platessoides avec D. ruber et D. lacustris étaient respectivement de 3 et 10%. Les divergences ITS2 et cox1 entre Derogenes sp. de H. platessoides et d'autres espèces/lignées de Derogenes se situaient à des niveaux de différences interspécifiques. L'espèce de H. platessoides est décrite ici comme Derogenes abba n. sp. Nous avons également examiné le matériel type de Progonus muelleri (Levinsen, 1881), type et seule espèce du genre Progonus, avec une redescription et des désignations de paralectotypes. Sur la base de spécimens des collections de Theodor Odhner au Musée suédois d'histoire naturelle (SMNH), Stockholm, nous fournissons de nouvelles données morphologiques et anatomiques sur le complexe d'espèces de D. varicus sensu lato. Enfin, nous avons étudié la « collection perdue ¼ de Trématodes d'Arthur Looss au SMNH et caractérisé une espèce putative, Derogenes sp. « limula ¼.

Phylogeny and morphology of some European cyathocotylid digeneans (Trematoda: Diplostomoidea).

The Cyathocotylidae Mühling, 1898 is a family of primitive diplostomoid trematodes important for understanding the evolution of the superfamily Diplostomoidea. However, cyathocotylids remain poorly studied with the use of molecular techniques. In this study we sequenced the 5.8S + ITS2 region, 28S rRNA, and cox1 genes of two cyathocotylid species and obtained new morphological data on them. We propose Georduboisia nom. nov. instead of the preoccupied name Duboisia Szidat, 1936 (junior homonym of Duboisia Stremme, 1911). Adults of Georduboisia cf. teganuma (Ishii, 1935) and Paracoenogonimus ovatus Katsurada, 1914 were collected from fish-eating birds in the south of the European part of Russia. Georduboisia cf. teganuma was very similar to G.teganuma but differed from it in the shape of the testes. The 28S rRNA gene dataset provided the best-resolved phylogeny of the Cyathocotylidae to date. In the phylogram based on partial sequences of this gene, P. ovatus was close to members of Holostephanoides Dubois, 1983, Neogogatea Chandler & Rausch, 1947 and Gogatea Szidat, 1936. Georduboisia cf. teganuma clustered with members of Cyathocotyle Mühling, 1896 and Holostephanus Szidat, 1936. Phylogenetic analysis based on the 5.8S + ITS2 dataset showed that adults of P. ovatus examined in our study were conspecific with the metacercariae from the musculature of fish collected in Hungary and Italy. It also revealed probable misidentifications of larvae and adults of cyathocotylids whose sequences are deposited in GenBank NCBI.

Trematode infection in ruminants and diversity of snail hosts across three agro-ecological zones in Ethiopia.

The occurrence of trematodes among ruminants and their snail vectors is a major concern across various agro-ecological regions of Ethiopia. Trematodes pose significant threats to animals, causing considerable economic losses and impacting public health. In this study, we have investigated 784 ruminant fecal samples, and 520 abattoir samples, alongside the collection and identification of snail vectors from various agro-ecological regions. Fecal examinations revealed Fasciola, Paramphistomum and Schistosoma species infected 20.5% (95% CI: 17.6, 23.8), 11.7% (95% CI: 9.6, 14.2), and 6.3% (95% CI: 4.1, 9.1) of the animals, respectively. The overall prevalence of trematodes among ruminants was 28.8% (95% CI: 25.7, 32.1%), with 6.0% (95% CI: 4.3, 7.7) showing mixed infections. Fasciola was more prevalent in Asela (26%) compared to Batu (19%) and Hawassa (11.5%), while a higher proportion of animals in Batu were infected with Paramphistomum. Schistosoma eggs were detected only in Batu (12.5%), but not in other areas. Sheep and cattle exhibited higher infection rates with Fasciola, Paramphistoma, and Schistosoma compared to goats. Significant associations were observed between trematode infections and risk factors including agro-ecology, animal species, body condition score, and deworming practices. About 20.8% and 22.7% of the slaughtered animals harbored Fasciola and Paramphistomum flukes, respectively, with a higher prevalence in Asela and Hawassa abattoirs compared to Batu abattoir. Additionally, a total of 278 snails were collected from the study areas and identified as lymnae natalensis, lymnae trancatula, Biomphalaria pffiferi, Biomphlaria sudanica, and Bulinus globosus. In conclusion, the study highlights the widespread occurrence of trematode infections, emphasizing the need for feasible control measures to mitigate their economic and public health impacts.

Endoparasitic helminth fauna and diet of Geophagus sveni (Pisces) in Upper Paraná River basin.

In freshwater ecosystems, parasite infection patterns are influenced by factors including spatial-temporal variations, host diet, and habitat. Fish often change diets, affecting their parasite communities. This study focused on non-native host fish Geophagus sveni, aiming to characterize diet and endoparasitic helminth fauna patterns in the invaded area, investigating spatial and seasonal possible differences of endoparasite infections and correlating with host diet, in São José dos Dourados River and Tietê River areas. The host fish were collected in these areas during the dry and rainy season using gillnets. The endoparasites were collected and preserved in alcohol and identified using taxonomic methods, and stomach contents were examined for diet analysis. Parasitism descriptors were calculated and evaluated spatially and seasonally by ANOVA and the Kruskal-Wallis tests. PERMANOVA assessed G. sveni diet differences, and RDA correlated the endohelminth abundance with the host diet. Two endoparasites were recorded: metacercariae of Austrodiplostomum compactum (Trematoda) and larvae and adults of Raphidascaris (Sprentascaris) lanfrediae (Nematoda). Spatial differences were observed for the mean abundance and prevalence of R. (S.) lanfrediae and A. compactum prevalence. Seasonal variations of parasitic descriptors occurred for the nematode in the Tietê River area. The detritus and aquatic insects were the most consumed items by G. sveni. Detritus consumption positively correlates with nematode abundance. The findings indicate that factors such as artificial channels and rainfall, which can influence resource availability, may affect the fish's diet and potentially influence the structure of its endoparasite community. The study emphasizes the importance of understanding trophic chain-transmitted parasites and calls for further research in Neotropical environments.

Season, size, and sex: factors influencing monogenean prevalence and intensity on Gambusia affinis in New Zealand.

A number of studies have been conducted on monogenean seasonality, though primarily in continental regions with wide annual temperatures ranges. We investigated seasonal changes in the prevalence and intensity of Salsuginus seculus infesting sexually dimorphic western mosquitofish (Gambusia affinis) in New Zealand. This represents the first examination of seasonality for this species globally, and the first seasonal assessment of any monogenean population in New Zealand, a temperate country with a mild oceanic climate. Prevalence and intensity of S. seculus with respect to fish size and sex was also examined. Prevalence of S. seculus changed temporally, peaking in summer, and was strongly positively correlated with algal concentrations. This relationship may be associated with increasing food levels, leading to an increase in fish courting and mating, resulting in high numbers and close physical associations of G. affinis individuals, facilitating transmission of the monogeneans. Thus, biotic factors may be important in determining temporal changes in S. seculus prevalence in New Zealand. Female G. affinis had a significantly higher prevalence and mean intensity of S. seculus than males. Longer fish had a higher mean intensity and prevalence of S. seculus. Female G. affinis likely host disproportionately more monogeneans as they are larger than males. Alternatively, females may have a compromised immune response during reproductive periods. Overall, seasonal change was observed in S. seculus prevalence and intensity under New Zealand's mild climatic conditions, and the larger female G. affinis in this dimorphic species supported a greater prevalence and intensity of infestation than males.

Pathological, morphological, and molecular characterization of the infection by Brachycladium goliath in humpback whale Megaptera novaeangliae.

The humpback whale (Megaptera novaeangliae) is a cosmopolitan migratory, seasonal mysticete that frequents the Brazilian coast. Strands of specimens may occur during the migratory stay in the country. In 2021 and 2022, three live humpback whales stranded on the coast of Rio Grande do Sul and Santa Catarina states in southern Brazil. After euthanasia, specimens were necropsied, and organs were thoroughly examined for lesions. Grossly, in all three cases, the liver exhibited multifocal, irregular, firm, white areas on the hepatic capsule, which extended into the parenchyma. On the cut surface, the livers were yellow to pale brown with orangish to greenish areas, the bile ducts were prominent, thickened, and severely dilated, and leaf-shaped flukes were found inside of them. Additionally, one case showed moderate atrophy of the right hepatic lobe. The histological findings included dilation of bile ducts, hyperplasia of the bile duct epithelium, marked inflammatory infiltration of lymphocytes, plasma cells, and eosinophils, and portal fibrosis. The parasite Brachycladium goliath was both morphologically and molecularly identified based on diagnostic key for trematodes and the original description of the species, and the amplification and sequencing of the ITS-2 region, respectively. Even though hepatic injury was not the primary cause of stranding, it may have contributed to the debilitation of the whales. To the authors' knowledge, this is the first study that reports M. novaeangliae as a definitive host of B. goliath and that describes the lesions caused by the parasite in cetaceans.

Identification of Lepidapedon oregonense as the current world's deepest trematode.

The deepest recorded depth for trematodes currently stands at approximately 6200 m. This depth record was achieved solely through sequence datasets of Lepidapedon sp. obtained from a gastropod. Given that trematodes of this genus typically use fish as definitive hosts, the origin of the trematode sequence was thought to be larval stages. However, the specific species remained unclear owing to the absence of reported adult-stage sequences. In the present study, we definitively identified the deepest trematode as Lepidapedon oregonense by comparing 28S ribosomal DNA sequences from adult worms from the macrourid fish Coelorinchus gilberti with data from the gastropod in the previous study.

Two new Neotetraonchus species (Dactylogyridea, Dactylogyridae) parasitising the Peruvian sea catfish Galeichthys peruvianus (Siluriformes, Ariidae), including molecular data.

As part of a parasitological survey, several specimens of two new monopisthocotylean species, Neotetraonchus celsomanueli sp. nov. and N.peruvianus sp. nov. (Dactylogyridea, Dactylogyridae), were collected from the gill filaments of the Peruvian sea catfish Galeichthys peruvianus (Siluriformes, Ariidae) off Puerto Pizarro, Tumbes region, Peru. Neotetraonchus celsomanueli sp. nov. is characterised by an MCO with a T-shaped distal end and an accessory piece that is ribbed and expanded proximally with a worm-shaped termination. Neotetraonchus peruvianus sp. nov. is typified by its MCO, which has a sledgehammer-shaped distal end and an accessory piece with a claw-shaped distal end. Additionally, N.peruvianus sp. nov. is characterised by its jellyfish-shaped onchium. A partial 28S rDNA sequence was obtained from N.celsomanueli sp. nov., and a phylogenetic analysis was conducted. This analysis revealed the phylogenetic position of Neotetraonchus celsomanueli sp. nov. within a clade comprising monopisthocotylean parasites of diadromous and marine ariid catfishes, including Hamatopeduncularia spp., Chauhanellus spp., Thysanotohaptor Kritsky, Shameem, Kumari & Krishnaveni, , and Neocalceostomoides spinivaginalis Lim, 1995. This finding brings the number of known Neotetraonchus species to seven and represents the first described Neotetraonchus species infecting marine catfishes from Peru.

Description of three new species of Gyrodactylus von Nordmann, 1832 (Monogenea: Gyrodactylidae) on bitterling fishes (Acheilognathinae) from China.

Three new species of Gyrodactylus are described from three species of bitterling in Donghu Lake, China: Gyrodactylus ocellorhodei n. sp. from Rhodeus ocellatus; G. sinenorhodei n. sp. from Rhodeus sinensis; and G. acheilorhodei n. sp. from Acheilognathus macropterus. All the three new species showed similar opisthaptor morphology, especially the marginal hooks: all had a slender and perpendicular sickle shaft, and flat sickle base with distinct heel and inner arch which was different from the G. rhodei-group species parasitic on bitterling. Multivariate analyses based on hamulus and marginal hooks suggested that these three new species cannot be completely distinguished, despite some morphology divergence observed in certain less reliable morphometric features, such as hamulus root length, ventral bar total length and process shape. These three new species shared an identical 18S ribosomal RNA gene sequence, while the variation in the Internal Transcribed Spacers (ITS1-ITS2) sequence among them (8.4-11.2%, K2P) far exceeded the 1% ITS sequence difference that had been suggested as a threshold for species delimitation of Gyrodactylus. Phylogenetic analysis based on ITS1-ITS2 showed that all these sequenced Gyrodactylus spp. parasitic on the subfamily Acheilognathinae host formed a monophyletic group. However, a clear differentiation (18.9-20.9%, K2P of ITS1-ITS2) could be found between the subgroup from China (G. ocellorhodei n. sp., G. sinenorhodei n. sp. and G. acheilorhodei n. sp.) and that from Europe (G. rhodei).

Integrative Taxonomy of Prosogonotrema bilabiatum Vigueras, 1940 (Digenea: Sclerodistomidae): A Parasite in Atlantic Spadefish Chaetodipterus faber (Broussonet, 1782) (Acanthuriformes: Ephippidae) from Brazil.

OBJECTIVES: The present work aims to expand the knowledge of the digenean species Prosogonotrema bilabiatum (Sclerodistomidae), a parasite of Chaetodipterus faber (Acanthuriformes) from Brazil, with an integrative taxonomic approach, using light microscopy, scanning electron microscopy, histology, and molecular biology. METHODS: Forty-one digenean specimens were stained with hydrochloric carmine for morphological studies. Eleven parasites were dehydrated through a graded ethanol series, critical point dried with carbon dioxide, and coated with gold for scanning electron microscopy analysis. Four specimens were processed following histological routine and stained with hematoxylin and eosin and Gomori trichrome. DNA extracted was amplified using 28S partial primer D1-D3. Maximum likelihood and Bayesian inference were performed for phylogenetic analysis. RESULTS: Morphometric and morphological data of the specimens studied ranged in accordance as observed in previous descriptions of the species. Observations from scanning electron microscopy and histology corroborated with those observed in stained whole mounts. Molecular analysis showed that specimens of P. bilabiatum from Brazil clustered with another two sequences of this species from different hosts and localities, with a high node support value. CONCLUSIONS: The integrative taxonomic approach allowed to record and describe new characteristics of P. bilabiatum related to the tegument, the structure and the arrangement of its tissues. The use of molecular markers confirmed that specimens identified as P. bilabiatum from different hosts and localities are all conspecific. Further studies, mainly molecular with less conserved genetic markers, should be carried out to better understand the phylogenetic relationships of Prosogonotrema with Hemiuroidea.

Lepocreadiidae (Trematoda) associated with gelatinous zooplankton (Cnidaria and Ctenophora) and fishes in Australian and Japanese waters.

We examined gelatinous zooplankton from off eastern Australia for lepocreadiid trematode metacercariae. From 221 specimens of 17 species of cnidarian medusae and 218 specimens of four species of ctenophores, infections were found in seven cnidarian and two ctenophore species. Metacercariae were distinguished using cox1 mtDNA, ITS2 rDNA and morphology. We identified three species of Prodistomum Linton, 1910 [P. keyam Bray & Cribb, 1996, P. orientale (Layman, 1930), and Prodistomum Type 3], two species of Opechona Looss, 1907 [O. kahawai Bray & Cribb, 2003 and O. cf. olssoni], and Cephalolepidapedon saba Yamaguti, 1970. Two species were found in cnidarians and ctenophores, three only in cnidarians, and one only in a ctenophore. Three Australian fishes were identified as definitive hosts; four species were collected from Scomber australasicus and one each from Arripis trutta and Monodactylus argenteus. Transmission of trematodes to these fishes by ingestion of gelatinous zooplankton is plausible given their mid-water feeding habits, although such predation is rarely reported. Combined morphological and molecular analyses of adult trematodes identified two cox1 types for C. saba, three cox1 types and species of Opechona, and six cox1 types and five species of Prodistomum of which only two are identified to species. All three genera are widely distributed geographically and have unresolved taxonomic issues. Levels of distinction between the recognised species varied dramatically for morphology, the three molecular markers, and host distribution. Phylogenetic analysis of 28S rDNA data extends previous findings that species of Opechona and Prodistomum do not form monophyletic clades.

Gastropod invasions in anthropogenically impacted impoundments in South Africa: Tracing their origins and exploring field evidence of parasite spillback and amplification.

Invasive snails are associated with ecological problems in freshwater bodies worldwide. However, their impact on the transmission of digenean infections remain underreported. In the present study, 1708 specimens representing four snail species were sampled from four impoundments in the Limpopo River system in South Africa. Gyraulus chinensis (Planorbidae), Physella acuta (Physidae) and Pseudosuccinea columella (Lymnaeidae), which are invasive, were found in all the sampling sites. In contrast, the native lymnaeid Radix natalensis occurred at only one study site. Digeneans were observed only from R. natalensis (prevalence = 49%) and Ps. columella (prevalence = 23%). Morphological and genetic analyses revealed four digeneans: Fasciola nyanzae, Orientocreadium sp., Petasiger sp. and Patagifer vioscai. Pseudosuccinea columella was infected by the four digeneans while R. natalensis harboured only Orientocreadium sp. and Petasiger sp. Partial sequences of Orientocreadium sp. from the current study differed from congeners whose DNA data are available on GenBank, by p-distances of at least 1.84 and 2.2% for 28S and the internal transcribed spacer (ITS) rDNA, respectively. Phylogenetic analyses demonstrated that the present species is sister to Orientocreadium batrachoides. Genetic and phylogenetic data based on 28S and ITS rDNA suggested that Petasiger sp. from the present study and isolates of three unidentified Petasiger spp. from Kenya, Hungary and Australia, were representatives of the same species. This is the first known report of Orientocreadium, Petasiger and Patagifer from Ps. columella. The occurrence of F. nyanzae in Ps. columella indicates spillback from R. natalensis. These findings echo the concerns raised in previous studies about the potential role of Ps. columella in the amplification of digenean diseases in its introduced range. Phylogenetic analyses of partial sequences of the cytochrome c oxidase subunit 1 mitochondrial gene (cox1) showed multiple lineages of Ps. columella in North and South America. Pseudosuccinea columella specimens from the present study belong to an invasive genotype that has spread globally and has been reported from Zimbabwe, Egypt, Portugal, Australia, Argentina, Colombia and New Mexico (USA). Physella acuta from the current study had a stronger genetic relationship with isolates from Canada and Iceland, than with isolates from other parts of Africa, suggesting several invasion routes into Africa. This is the first known DNA characterisation of G. chinensis from Africa. Phylogenetic reconstruction indicated multiple exit events of G. chinensis from Asia into Europe and Africa. South African isolates clustered in a recent branch containing isolates from the Czech Republic and Hong Kong, China. Considering the presence of invasive snails in all the sampling sites in the present study, it is necessary to investigate the factors that enhance their establishment and to monitor their effects on the native snail populations.

Description of two new species of dactylogirids (Monogenoidea: Dactylogyridae) from Mylossoma albiscopum (Cope, 1872) (Characiformes: Serrasalmidae) from the Peruvian Amazonia.

INTRODUCTION: Two new dactylogyrid monogeneans, Anacanthorus cultro n. sp. and Notozothecium palometae n. sp., are described based on specimens collected from the gill filaments of Mylossoma albiscopum (Cope, 1872) (Characiformes: Serrasalmidae), a pelagic and herbivore teleost collected in the Tigre river, Loreto, Peru. MATERIALS AND METHODS: Some monogeneans were stained with Gomori's trichrome and mounted in Canada Balsam to determine internal soft structures. Others were cleared in Hoyer's medium for the study of sclerotized structures. Drawings were made using a drawing tube and a microprojector. RESULTS: Anacanthorus cultro n. sp. is characterized by the presence of a rod-shaped male copulatory organ (MCO) lacking featherlike structures, and a knife-shaped accessory piece with a submedial knob. Notozothecium palometae n. sp. can be distinguished from all congeners by its MCO with a subbasal spur and an accessory piece with inverted hammer shaped. CONCLUSIONS: This is the first data on the parasites of M. albiscopum, a popular fish in local markets. Anacanthorus cultro n. sp. is the twenty-fifth documented species of the genus in Peru, while N. palometae n. sp. represents the seventh species of the genus known to infect freshwater fish species in Peru.

A report on the complete mitochondrial genome of the trematode Azygia robusta Odhner, 1911, its new definitive host from the Russian Far East, and unexpected phylogeny of Azygiidae within Digenea, as inferred from mitogenome sequences.

New data on the complete mitochondrial genome of Azygia robusta (Azygiidae) were obtained by the next-generation sequencing (NGS) approach. The mitochondrial DNA (mtDNA) of A. robusta had a length of 13 857 bp and included 12 protein-coding genes, two ribosomal genes, 22 transfer RNA genes, and two non-coding regions. The nucleotide sequences of the complete mitochondrial genomes of two A. robusta specimens differed from each other by 0.12 ± 0.03%. Six of 12 protein-coding genes demonstrated intraspecific variation. The difference between the nucleotide sequences of the complete mitochondrial genomes of A. robusta and Azygia hwangtsiyui was 26.95 ± 0.35%; the interspecific variation of protein-coding genes between A. robusta and A. hwangtsiyui ranged from 20.5 ± 0.9% (cox1) to 30.7 ± 1.2% (nad5). The observed gene arrangement in the mtDNA sequence of A. robusta was identical to that of A. hwangtsiyui. Codon usage and amino acid frequencies were highly similar between A. robusta and A. hwangtsiyui. The results of phylogenetic analyses based on mtDNA protein-coding regions showed that A. robusta is closely related to A. hwangtsiyui (belonging to the same suborder, Azygiida) that formed a distinct early-diverging branch relative to all other Digenea. A preliminary morphological analysis of paratypes of the two azygiid specimens studied showed visible morphological differences between them. The specimen extracted from Sakhalin taimen (Parahucho perryi) was most similar to A. robusta. Thus, we here provide the first record of a new definitive host, P. perryi, for A. robusta and also molecular characteristics of the trematode specimens.

Nematodes and trematodes associated with terrestrial gastropods in Nottingham, England.

A parasitological survey of terrestrial slugs and snails was conducted at popular dog walking locations across the city of Nottingham, with the intensions of finding gastropods infected with parasites of medical (or veterinary) importance such as lungworm (metastrongyloid nematodes) and trematodes. A total of 800 gastropods were collected from 16 sites over a 225 km2 area. The extracted nematodes and trematodes were identified by molecular barcoding. Of the 800 gastropods collected, 227 were infected (172 had nematode infections, 37 had trematode infections and 18 had both nematode and trematode infections). Of the nematode infected gastropods genotyped, seven species were identified, Agfa flexilis, Angiostoma gandavense, Angiostoma margaretae, Cosmocerca longicauda, Phasmarhabditis hermaphrodita, Phasmarhabditis neopapillosa and an unknown Cosmocercidae species. Of the trematode infected gastropods genotyped, four species were identified, Brachylaima arcuate, Brachylaima fuscata, Brachylaima mesostoma and an unknown Plagiorchioidea species. No lungworm species were found within the city of Nottingham. To our knowledge, this study represents the first survey of gastropod-associated nematodes and trematodes in the East midlands of the United Kingdom.

RECRUITMENT AND SEASONAL OCCURRENCE OF PARASITES IN JUVENILE INVASIVE ROUND GOBIES (NEOGOBIUS MELANOSTOMUS) IN THE ST. LAWRENCE RIVER, QUEBEC, CANADA.

The round goby (Neogobius melanostomus) is an invasive species that has become one of the most abundant fish in the St. Lawrence River, Quebec, Canada over the past 15 yr. Since its introduction, the round goby has acquired a number of native parasites, yet little is known about the dynamics of parasite recruitment. To examine this question, young-of-the-year and juvenile round gobies were collected monthly from 2 localities in the river (Îles de la Paix, Île Dorval) from June through November 2012. At Îles de la Paix, round gobies (n = 180) were infected with 3 species of parasites, all larval stages (Diplostomum spp., Tylodelphys scheuringi, Neoechinorhynchus tenellus). Prevalence of the digenean Diplostomum spp. varied from 3.3 to 13.3%, and mean abundance from 0.03 to 0.53 from June through September, with a maximum in August. The digenean T. scheuringi was seen only in August, at a prevalence of 10.0% and a mean abundance of 0.53. The acanthocephalan N. tenellus was observed in June, August, and September, prevalence ranging from 3.3 to 10.0% and mean abundance from 0.03 to 0.27. Maximum infection for all 3 species occurred in August. All infected fish were ≥44 mm in total length (TL). Fish infected with more than 1 parasite species were >60 mm TL. No round goby (n = 178) was infected at Île Dorval. This study demonstrated that the invasive round goby starts to acquire parasite infections in the St. Lawrence River in the first year of life and may contribute to the transmission of some parasites within this ecosystem.