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.

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.

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.

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.

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.

Immunological and molecular evaluation of zoonotic metacercarial infection in freshwater fish: A cross-sectional analysis.

Improperly cooked fish, carrying active metacercariae (MCs), can pose a significant risk for transmitting fish-borne zoonotic trematodes (FBZTs) to human consumers. This study aimed to enhance our understanding of FBZTs by conducting a comprehensive cross-sectional analysis involving various fish species, such as Nile tilapia (Oreochromis niloticus), African catfish (Clarias gariepinus), and red-belly tilapia (Tilapia zillii). These fish specimens were collected from distinct Egyptian governorates, specifically Giza, Kafr al-Shaykh, and Fayoum. The recovered flukes from experimentally infected domestic pigeons were identified as Prohemistomum vivax, Haplorchis pumilio, and Pygidiopsis genata based on morphological features. Furthermore, the identity of the retrieved adult flukes was confirmed using three species-specific primers for PCR amplification and sequencing analysis of the ITS rDNA region and have been deposited in GenBank with the following accession numbers: P. vivax (OR291421.1 and OR291422.1), P. genata (OP099561.1), and H. pumilio (OM439581.1-OP090510.1). Quantitative real-time PCR targeting the immunological genes Tumor Necrosis Factor-alpha (TNF-alpha) and Interleukin-1 (IL-1Β) was employed to compare the cellular immune response between infected with EMCs and uninfected O. niloticus. The results indicated a significant increase in TNF- and IL-1Β levels in FBZTs-infected vs un-infected fishes. Importantly, the presence of adult flukes and EMCs led to substantial histological alterations in both experimentally infected pigeons and naturally infected fish tissues. These changes included the necrosis of fish muscle bundles and a pronounced inflammatory reaction with muscular necrosis in the digestive tracts of experimentally infected pigeons.

Calicophoron daubneyi (Paramphistomidae) in deer of the Sumava National Park, Czech Republic - Consequence of prevalent rumen fluke infection in cattle.

A substantial parallel increase in prevalence and geographical spread of the rumen fluke, Calicophoron daubneyi, in livestock in western and central Europe has been recognized in the recent past. In the course of the examination of rectum feces of 471 red deer (Cervus elaphus) and one sika deer (Cervus nippon) from the Fascioloides magna endemic Sumava National Park in the years 2021 and 2022, rumen fluke eggs were detected in four red deer (0.8%) and the sika deer and identified as eggs of C. daubneyi by molecular analysis. Subsequent examination of rectal fecal samples of 247 beef cattle from 22 herds of 14 farms located in or nearby the national park revealed rumen fluke eggs in 53 samples (21.5%) originating from 16 herds of 11 farms, molecularly identified as C. daubneyi eggs as well. One C. daubneyi egg positive red deer and three C. daubneyi egg positive cattle samples also contained fasciolid eggs, respectively, which were detected in 9.5% or 3.6% of the total samples from red deer or cattle, respectively. Results of this investigation reveal the first finding of C. daubneyi in sika deer worldwide and in red deer in mainland Europe and add to the growing number of reports on C. daubneyi in livestock in Europe. Considering that the ratio of cattle excreting rumen fluke eggs exceeded that of deer substantially, it can reasonably be assumed that the C. daubneyi infections in deer are a consequence of the prevalent infection in cattle, illustrating a pathogen spillover event from livestock into wildlife.

Morphological and molecular data on Pseudozoogonoides ugui Shimazu, 1974 (Digenea: Microphalloidea: Zoogonidae) ex Pseudaspius hakonensis (Günther, 1877) and taxonomic problems in Zoogoninae genera.

New morphological and molecular data were generated for trematodes recovered from the intestines of the fish Pseudaspius hakonensis from two locations in the south of the Russian Far East. Morphologically, these trematodes are identical to Pseudozoogonoides ugui (Microphalloidea: Zoogonidae) from Japan. According to results of phylogenetic analysis based on 28S rDNA sequence data, P. ugui was closely related to Zoogonoides viviparus, and P. subaequiporus appears as a sister taxon to these two species. Genetic distance values, calculated based on both 28S rDNA and ITS2 rDNA, between P. ugui and Z. viviparus represents an interspecific differentiation level. Our results have an ambiguous explanation, indicating that the implication of the presence of one or two compact vitellarial aggregations for the differentiation of Zoogonoides and Pseudozoogonoides should be reconsidered or that our results open up the question of the taxonomical status of trematodes previously denoted as Z. viviparus and P. subaequiporus.

Transversotrema hafniensis n. sp. infection in Poecilia reticulata by cercariae released from Melanoides tuberculata in Denmark.

BACKGROUND: Exotic and ornamental fish are highly popular companion animals resulting in a significant transcontinental trade of fish, invertebrates and aquatic plants. A major issue is the diseases associated with these organisms, as they have a major impact on health of the fish in both public and private household aquaria. A secondary issue is the trade with these products, which potentially may expand the distribution area and spread a range of diseases to new habitats. RESULTS: We here describe how Poecilia reticulata (guppy), produced in a private household aquarium, were invaded by cercariae of an exotic trematode released by imported Melanoides tuberculata snails. The fish presented with severe clinical signs (tremor, flashing, scraping of body against objects). A standard parasitological examination and morphometric identification showed scale pocket infections with a digenean trematode species within the genus Transversotrema. Molecular identification by PCR, sequencing and phylogenetic analyses of a 2646 bp sequence encoding ribosomal RNA (partial 18 S, ITS1, 5.8 S, ITS2, partial 28 S) was performed. The 1107 bp sequence of mitochondrial DNA (cox1) showed that the parasite differed from previously described Transversotrema species in M. tuberculata. Morphometrics of adult and larval specimens of this isolate also differed from previously described freshwater species within the genus. The new species was described and is named after Copenhagen, for its geographic origin. CONCLUSIONS: The genus Transversotrema comprises a range of species, adapted to a microhabitat in scalepockets of teleosts. A combination of morphological and molecular characterization techniques has been shown to provide a good differentiation between species. The fish were not purchased from a pet shop but produced in the home aquarium. This indicated that an infection pressure existed in the aquarium, where the source of infection was found to be exotic intermediate host snails M. tuberculata, which originally were imported and purchased from a pet shop. The potential spread of fish diseases associated with trade of fish and snails to new geographic regions, where climate conditions are favourable, is discussed.

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.

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.

Epidemiology of rumen fluke infection in selected buffalo farms in perak, malaysia: prevalence, molecular species identification, and associated risk factors.

Rumen flukes cause heavy economic losses in the ruminant industry worldwide, especially in tropical and subtropical countries. This study estimated the prevalence of rumen flukes in buffaloes, identified the species diversity, and determined risk factors associated with rumen fluke prevalence in Perak, Peninsular Malaysia. A cross-sectional study was conducted, and 321 faecal samples were collected from six buffalo farms. A structured questionnaire was developed, and farmers were interviewed to obtain information regarding risk factors associated with rumen fluke infection. The faecal samples were examined using sedimentation and Flukefinder® techniques. Genomic DNA was extracted from the fluke eggs recovered using the Flukefinder® method, and the internal transcribed spacer 2 (ITS2) fragment was amplified and sequenced to facilitate species identification. The results showed that the overall prevalence of rumen fluke across the sampled farms was 40.2% (129/321). Three rumen fluke species were identified, namely, Fischoederius elongatus, F. cobboldi, and Orthocoelium streptocoelium. Several management factors had a significant association (P < 0.05) with rumen fluke prevalence, including production type, cleaning of the stable, drinking water system, flooding around the farm, grazing system, pasture sharing with other livestock, and deworming program. This work constitutes the first attempt to understand the epidemiology of rumen fluke infection in the region and suggests that good farm management, pasture management, choosing appropriate drugs, and proper husbandry practices may improve buffalo health and production in areas where rumen flukes are prevalent.

Expanding the swimmer's itch pool of the Benelux: a first record of the neurotropic Trichobilharzia regenti and potential link to human infection.

BACKGROUND: Swimmer's itch, an allergic contact dermatitis caused by avian and mammalian blood flukes, is a parasitic infection affecting people worldwide. In particular, avian blood flukes of the genus Trichobilharzia are infamous for their role in swimmer's itch cases. These parasites infect waterfowl as a final host, but incidental infections by cercariae in humans are frequently reported. Upon accidental infections of humans, parasite larvae will be recognized by the immune system and destroyed, leading to painful itchy skin lesions. However, one species, Trichobilharzia regenti, can escape this response in experimental animals and reach the spinal cord, causing neuroinflammation. In the last few decades, there has been an increase in case reports across Europe, making it an emerging zoonosis. METHODS: Following a reported case of swimmer's itch in Kampenhout in 2022 (Belgium), the transmission site consisting of a private pond and an adjacent creek was investigated through a malacological and parasitological survey. RESULTS: Six snail species were collected, including the widespread Ampullaceana balthica, a well-known intermediate host for Trichobilharzia parasites. Shedding experiments followed by DNA barcoding revealed a single snail specimen to be infected with T. regenti, a new species record for Belgium and by extension the Benelux. Moreover, it is the most compelling case to date of the link between this neurotropic parasite and cercarial dermatitis. Additionally, an Echinostomatidae sp. and Notocotylus sp. were isolated from two other specimens of A. balthica. However, the lack of reference DNA sequences for these groups in the online repositories prevented genus- and species-level identification, respectively. CONCLUSIONS: The presence of T. regenti in Belgium might have severe clinical implications and its finding highlights the need for increased vigilance and diagnostic awareness among medical professionals. The lack of species-level identification of the other two parasite species showcases the barcoding void for trematodes. Overall, these findings demonstrate the need for a Belgian framework to rapidly detect and monitor zoonotic outbreaks of trematode parasites within the One Health context.

Integrative taxonomy of Anaporrhutum mundae sp. nov. (Trematoda: Gorgoderidae), a parasite of the Munda round ray Urotrygon munda (Urotrygonidae) in Costa Rica.

A new species of trematode of anaporrhutine gorgoderid, from the gill chambers of the Munda round ray Urotrygon munda in Costa Rica is described, based on an integrative taxonomic approach that includes the use of light and scanning electron microscopy, ITS2 and 28S rDNA sequencing, and phylogenetic analysis. Anaporrhutum mundae sp. nov. can be distinguished from congeneric species by a combination of morphological traits and particularly by having the genital pore opening at the level of the intestinal bifurcation. The new species also can be distinguished from all other species of Anaporrhutum, except A. euzeti Curran, Blend & Overstreet, 2003, by having fewer testicular follicles per testis. Anaporrhutum mundae sp. nov. also differs from A. euzeti in its forebody shape and by having different morphology and location of the vitellaria. The study of the tegumental surface of A. mundae sp. nov., as revealed by scanning electron microscopy, allowed detection of new morphological characters for a member of Anaporrhutinae that may be of taxonomic value. These are: a stylet cavity dorsal to the oral sucker with a large penetration gland opening on each side of the cavity and small penetration gland openings located ventral to the stylet cavity, arranged in a circle around the mouth. This represents the first record of an Anaporrhutum species from Costa Rica. Further, A. mundae sp. nov. represents the first parasite described or reported in this host.

DULCITRANSVERSOTREMA N. GEN. (DIGENEA: TRANSVERSOTREMATIDAE) AND FIRST MORPHOLOGICAL AND NUCLEOTIDE-BASED CONFIRMATION OF THE LIFE CYCLE OF A TRANSVERSOTREMATID IN NORTH AMERICA.

We propose Dulcitransversotrema n. gen. for the freshwater transversotrematids Dulcitransversotrema patialense (Soparkar, 1924) n. comb. and Dulcitransversotrema chauhani (Agrawal and Singh, 1960) n. comb. Dulcitransversotrema is unique by the combination of lacking an oral sucker and an extensively coiled uterus as well as having testes that are not deeply lobed and that abut or nearly abut the inner posterolateral margins of the digestive tract (vs. deeply lobed testes that abut the cyclocoel region of the digestive tract only or that do not abut the ceca), a pre-oral genital pore (vs. post-oral genital pore), an ovary that is anterior to and abuts or nearly abuts the sinistral testis (vs. an ovary that is separated from the sinistral testis by some distance or having an ovary that is median and immediately pre-testicular), non-embryonated eggs (vs. embryonated eggs), typically having none or sparse vitelline follicles between the testes and ceca (vs. having a wholly inter-cecal vitellarium comprising a pair of highly compacted clusters of vitelline follicles anterolateral to the testes or having numerous vitelline follicles between the testes and ceca), an oblong, median, and primarily inter-testicular vitelline reservoir (vs. an extensively elongate, pre-testicular vitelline reservoir that arches anteriorly around the sinistral testis), and a subterminal excretory pore opening on the dorsal body surface between the level of the cyclocoel and posterior body end (vs. a terminal excretory pore). We describe the redia and cercaria of Dulcitransversotrema cf. patialense from the red-rimmed melania snail, Melanoides tuberculata (Müller, 1774) (Cerithioidea: Thiaridae), and their corresponding adult from beneath the scales of the zebrafish, Danio rerio (Hamilton, 1822) (Cypriniformes: Danionidae). All hosts were sampled from a spring-fed earthen pond at a private aquaculture facility near Ruskin, Florida. No transversotrematid life cycle was known from North America previously. The large subunit ribosomal DNA and ribosomal internal transcribed spacer 2 sequences of D. cf. patialense from Florida were most similar to those from D. patialense infecting red-rimmed melania from Mayagüez, Puerto Rico and differed by 134 and 69 nucleotides, respectively. Both phylogenetic analyses recovered Dulcitransversotrema as monophyletic and sister to a clade comprising Transversotrema spp. plus Crusziella formosa Cribb, Bray, and Barker, 1992.

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.

An integrative taxonomy study reveals a rare new species of the genus Creptotrema (Trematoda: Allocreadiidae) in an endangered frog in South America.

During an ecological study with a near-endangered anuran in Brazil, the Schmidt's Spinythumb frog, Crossodactylus schmidti Gallardo, 1961, we were given a chance to analyze the gastrointestinal tract of a few individuals for parasites. In this paper, we describe a new species of an allocreadiid trematode of the genus Creptotrema Travassos, Artigas & Pereira, 1928, which possesses a unique trait among allocreadiids (i.e., a bivalve shell-like muscular structure at the opening of the ventral sucker); the new species represents the fourth species of allocreadiid trematode parasitizing amphibians. Besides, the new species is distinguished from other congeners by the combination of characters such as the body size, ventral sucker size, cirrus-sac size, and by having small eggs. DNA sequences through the 28S rDNA and COI mtDNA further corroborated the distinction of the new species. Phylogenetic analyses placed the newly generated sequences in a monophyletic clade together with all other sequenced species of Creptotrema. Genetic divergences between the new species and other Creptotrema spp. varied from 2.0 to 4.2% for 28S rDNA, and 15.1 to 16.8% for COI mtDNA, providing robust validation for the recognition of the new species. Even though allocreadiids are mainly parasites of freshwater fishes, our results confirm anurans as hosts of trematodes of this family. Additionally, we propose the reallocation of Auriculostoma ocloya Liquin, Gilardoni, Cremonte, Saravia, Cristóbal & Davies, 2022 to the genus Creptotrema. This study increases the known diversity of allocreadiids and contributes to our understanding of their evolutionary relationships, host-parasite relationships, and biogeographic history.

Two new species of Monopisthocotyla (Dactylogyridea: Dactylogyridae) parasitizing the nasal cavities of Bryconops melanurus (Characiformes: Iguanodectidae) from coastal drainages of the Eastern Amazon, Brazil.

The present study integrates molecular and morphological data to support the proposal of new species of Telethecium Kritsky, Van Every & Boeger, 1996 and Diaphorocleidus Jogunoori, Kritsky & Venkatanarasaiah, 2004 from the nasal cavities of Bryconops melanurus (Bloch) of the coastal drainages of the Eastern Amazon. Telethecium tiquira sp. n. is characterized by possessing a male copulatory organ (MCO) with two circular sclerotized brims on the base, a coiled tubular shaft having 1 counterclockwise rings, an accessory piece with enlarged base, pincer-shaped at the distal portion; a sclerotized calyx-shaped vaginal vestibule, and hooks with proximal shank dilatation comprising 3/4 of the shank length. Also, Telethecium tiquira sp. n. can be easily distinguished from other species of the genus by the absence of a protruding bag located at the level of the copulatory complex. Diaphorocleidus forficata sp. n. is characterized by having a MCO with two counterclockwise rings, circular sclerotized tandem brim associated with the base of the MCO; accessory piece non-articulated with the MCO, bifurcate, pincer-shaped; vaginal pore sinistral-ventral with opening marginal, vaginal canal sclerotized, elongated, comprising one loop in the proximal portion before entering to the seminal receptacle; ventral anchor with shaft elongated and evenly curved on the axis; point short and slightly curved, and hooks similar in shape and size, hooks with proximal dilatation comprising approximately of the shank length. Furthermore, D. forficata sp. n. is supported by phylogenetic analysis based on sequences of the partial 28S rDNA gene, which placed D. forficata sp. n. in a well-supported clade of Diaphorocleidus spp. of characiform fishes. Thus, the two new species described here expand our knowledge about the diversity of monopisthocotylan parasites from the nasal cavities of Neotropical fishes. The findings of this study provide valuable insights into the biodiversity of the region and highlight the importance of further research in this area.

Description of Saccocoelioides miguelmontesi n. sp. (Digenea: Haploporidae) from characid fishes in the Iguazu River Basin based on morphological and molecular evidence.

Here we describe a new species of the genus Saccocoelioides found parasitizing Astyanax dissimilis Garavello & Sampaio, Psalidodon bifasciatus (Garavello and Sampaio) and Bryconamericus ikaa Casciotta, Almirón & Azpelicueta from the Iguazu National Park, Misiones province, Argentina. Saccocoelioides miguelmontesi n. sp. was studied based on morphological and molecular (28S rDNA and COI mtDNA sequences) data. The COI mtDNA tree indicated that the specimens collected from the three fish hosts are conspecific, with an intragroup p-distance of 0%. The new species shows an intermediate morphological configuration between the diminutive and robust forms described for Saccocoelioides by Curran (2018). Although, in the 28S rDNA tree, it is placed in a well-supported clade with the two robust species analysed (S. elongatus and S. magnus; p-distance of 1 and 2%, respectively), it differs from the robust group by the range of body size, mature egg size, oral and ventral sucker size, sucker ratio, oral sucker to pharynx ratio, and post-cecal or post-testis/body length percentage. Our results led us to redefine the robust group as having eggs shorter or equal in length to the pharynx. Saccocoelioides miguelmontesi n. sp. the 10th species reported from Argentina and the 7th species within the robust group.