Parkinson's disease (PD) is a prevalent neurological disorder and the second most common neurodegenerative disease. Research has explored the impact of infectious agents, such as the parasites, on neurological conditions, including PD. Given the limited studies worldwide and in Iran, this study aims to investigate the relationship between Toxocara infection and PD. This case-control study involved 91 PD patients and 90 healthy controls. After obtaining consent, serum samples and questionnaires were collected. All sera were examined using an ELISA test for IgG antibodies against Results were analyzed with SPSS, using chi-square tests, and odds ratios (OR), and confidence intervals (CI) were calculated via univariate and multivariate analyses. The prevalence of anti- IgG was 33% (30/91) in PD patients and 33.3% (30/90) in the control group. Both univariate analysis (OR: 0.98; 95% CI: 0.52-1.82) and multivariate analysis (OR: 0.95; 95% CI: 0.49-1.83) indicated no statistically significant association. Additionally, univariate analysis (OR: 0.49; 95% CI: 0.16-1.5) and multivariate analysis (OR: 0.37; 95% CI: 0.09-1.43) suggested non-significant association between infection and the severity of PD. Our findings do not support a statistically significant association between infection and the PD. While the analysis suggested that infection might reduce the severity of PD, these results were also not statistically significant. Further research with larger sample sizes and diverse populations is needed to fully understand the potential relationship between infection and PD.

The viruses associated with bats have generated significant concern; however, there is limited knowledge regarding the endoparasites that affect these mammals. This study involved the collection of seven nematode specimens (three males and four females) from the intestines of in Shaoguan City, Guangdong, China. Next-generation sequencing was employed to obtain the mitochondrial DNA (mtDNA) genome, which was determined to be 14,130 base pairs in length. The mitochondrial genome comprised 12 protein-coding genes, 21 tRNA genes, 2 rRNA genes, and an AT-rich non-coding region. Phylogenetic analyses based on mtDNA sequences indicated that the nematode forms a sister clade to , exhibiting only 74% nucleotide identity. In contrast, the nuclear ITS1 gene demonstrated a high degree of nucleotide identity (98.6%-98.8%) with Consequently, the parasitic nematode identified from is likely to belong to the genus and has been designated as sp. 888. Furthermore, an epidemiological investigation revealed the presence of the parasitic nematode infections in collected from Guangdong, Guangxi, and Guizhou Provinces. Given the widespread distribution of and their tendency to inhabit areas in close proximity to human dwellings, the influence of parasite prevalence on bat population numbers and potential for human and domestic animal transmission of this pathogen warrants further investigation.

is a genus of nematodes that cause ulcerative dermal lesions in large mammals. However, there is a dearth of knowledge on the molecular genetics of species infecting critically endangered rhinoceros. This study employed genetic barcoding genes to identify species and to determine its genetic diversity and evolution. Phylogenetic analyses on partial genes of the second internal transcribed spacer Ribosomal DNA (ITS-2) and cytochrome c oxidase subunit 1 (Cox-1), revealed a 77% and 93% bootstrap support at the Cox-1 and ITS-2 loci respectively to a clade containing previously identified species. Morphological examination also confirmed features diagnostic of previously known to infect rhinoceros. Gene diversity of Cox-1 was 0.931 ± 0.030 and 0.579 ± 0.104 for the ITS-2, whereas nucleotide diversity was 0.008 ± 0.002 and 0.00197 ± 0.0016 for the Cox-1 and ITS-2 genes respectively. Neutrality tests (Fu and Li's D* and Fu and Li's F*) were significantly negative (p<0.05) at all loci, whereas Tajima D and Fu's FS were each statistically significant (p<0.05) at the Cox-1 and ITS-2 loci respectively. The high gene diversity, low nucleotide diversity and negative neutrality tests are consistent with positive selection at the Cox-1 gene. infection among rhinoceros is currently restricted to highland sanctuaries compared to a widespread distribution in both lowlands and highlands in the 1960s suggesting an adaptation to vectors thriving in cooler highland temperatures. This is the first genetic identification of , in rhinoceros and will aid in diagnosis, treatment, studies, and rhinoceros conservation.

A BioBlitz is a rapid and intensive survey of a specific geographic area that brings together experts and often lay participants to assess biodiversity, typically of macrobiota that are easily observed and identifiable on-site. This concept has become popular across taxonomic fields, attracting interest globally to increase knowledge of local biodiversity. Inspired by the success of the approach, we undertook a 'ParasiteBlitz' at an unexplored locality (Stono Preserve, Charleston, South Carolina, USA) to determine its feasibility for parasites, whose assessment of diversity is largely neglected worldwide. We assembled a team of parasitologists with complementary expertise. Over 12 days (3 days in each habitat) in April 2023, we intensively screened fishes and aquatic invertebrates for parasites, and sampled sediment and water for environmental DNA (eDNA) metabarcoding from four aquatic habitats: wetland, freshwater pond, brackish impoundment, and tidal creek. We incorporated assistance from non-parasitologists and students. Details on methodologies and results are provided in individual papers in this Special Collection. Traditional methods revealed the presence of ca. 100 species of seven major metazoan parasite taxa, and the eDNA survey yielded over 1,000 amplicon sequence variants identified as parasites, most with sequences unmatched in GenBank, and resulting in only a few species identified as named species in the one-year post-Blitz timeframe we imposed upon ourselves for identification. Limitations and challenges of the ParasiteBlitz are discussed, and our results support that this approach can be effective for rapid discovery of the dimensions of parasite assemblages in an understudied environment and contribute to parasitology knowledge.

New, well-known and predicted life cycles for trematodes of the Haploporoidea (Haploporidae and Emprostiotrematidae) and three families of the Lepocreadioidea (Enenteridae, Gorgocephalidae, Gyliauchenidae) involve encystment of the metacercaria in the open (usually on vegetation) followed by ingestion by a range of herbivorous or detritivorous fishes. These life cycles appear among relatively highly derived plagiorchiidan trematodes in which three-host life cycles incorporating an animal second intermediate host are dominant. We hypothesise that the two-host life cycles in the Haploporoidea and Lepocreadioidea arose by secondary truncation of a three-host cycle; the second intermediate host was lost in favour of encystment in the open. Modification of a three-host life cycle effective for the infection of carnivores is consistent with the understanding that fishes arose as carnivores and that multiple lineages have secondarily become detritivores and herbivores. Four of the five trematode families involved infect fishes relating to multiple orders, suggesting a complex history of host-switching. In contrast, the Gorgocephalidae, the smallest of the families, has been found only in a single family, Kyphosidae. The timing of the evolutionary events leading to this putative life cycle truncation is yet to be deduced, but the rich developing understanding of the history of the fishes creates a strong template for future analysis.

Biological invasions are among the main threats to global biodiversity and present the potential to disrupt host-parasite dynamics. In Brazil, the scientific reports of the occurrence of the Amazonian fish 'pirarucu' () in the upper Paraná River basin, São Paulo state, were made in 2015. However, the effects of its introduction are still unknown, including those associated to its host-parasite relationships. As part of our studies on the possible effects of introduction into this basin, the parasites from the eyes of 60 specimens of were evaluated. We reported the occurrence of metacercariae (Trematoda, Diplostomidae) parasitizing the eyes of supported by morphological and molecular data (COI mtDNA). The new partial sequences had a similarity of 100% to other sequences of previously deposited in Genbank. Five hosts (Prevalence = 8.33%) with a standard length between 69 and 116 cm were infected, with a mean intensity of infection of 31.8 ± 17.2 (1-93). Large infected hosts are unlikely to be a significant prey item for the definitive hosts (medium-sized piscivorous birds), and could act as an 'ecological sink', disrupting the transmission of this metacercariae. Hosts with high infection rates by these metacercariae may present cataracts, exophthalmos, and blindness, resulting in loss of visual acuity. Considering that is a carnivorous and visual predator, the low infection observed possibly does not act as a biological filter to hinder or contain the invasion, probably presenting a low negative effect on the visual acuity of hosts.

In this study, morphological and molecular features were used to identify a new sp. from Kerala, India. Morphological and molecular features provide evidence for placing the new species into the clade. The new species is characterized by the following morphological features: infective juveniles with a body length of 1067 μm (914-1268 μm); a distance from the anterior end to excretory pore of 82 μm (73-92 μm); a distance from anterior end to nerve ring of 105 μm (91-118 μm). The distinguishing feature of the infective juveniles of n. sp. is the presence of seven ridges in the mid-body region, while all other species classified within the clade to date are characterized by eight ridges. The first-generation males are characterised by 25 genital papillae, very short spicules, with a length of 68 μm (60-72 μm), and the SW% ratio is 136 (114-169). The new species is further characterized by sequences of the internal transcribed spacer and partial 28S regions of the ribosomal DNA. Phylogenetic analyses show that n. sp. is closely related to species within the clade.

The parasites of Nile tilapia, (Linnaeus, 1758) are poorly documented in the United States despite the economic importance and global introduction of this African fish. Only one metazoan parasite ( Paperna, 1968; Gyrodactylidae) reportedly infects Nile tilapia in the United States. Examining Nile tilapia from a flow-through aquaculture system hydrologically linked to Sougahatchee Creek (Tallapoosa River, Auburn, Alabama), we observed a gill infection by Paperna & Thurston, 1969 (Dactylogyridae). This monogenoid was originally described from the gill of Mozambique tilapia, (Peters, 1852) from Lake Victoria, Uganda. Specimens of were studied for morphology and phylogenetic analyses using the and We identified our specimens as because they had the following combination of morphological features: marginal hooks shorter than dorsal anchor length; anchor roots reduced; dorsal anchor point bent; dorsal bar pyriform projections approximately half as long as dorsal bar width; penis short (<100 μm), not coiled, tubular, lacking swelling, having irregularly surfaced heel; and accessory piece straight and bifid. Our and phylogenies recovered our sequences in a clade with conspecific sequences and showed no obvious biogeographic pattern. reportedly infects 21 fishes of 11 genera and 3 families from 36 countries in Africa, Asia, North America, South America, and Europe. The study of Nile tilapia parasites, especially those exhibiting direct life cycles and low host specificity, is important because they comprise potential invasive species.

Human toxocariasis is a neglected parasitic disease with a global distribution, treated with current anthelmintics that have low to moderate efficacy, and requires the discovery of novel drugs. Camphor derivatives have antimicrobial properties against various pathogens such as fungi and bacteria. This study aimed to identify a camphor derivative with activity against larvae and evaluate its cytotoxicity, in silico bioavailability, and in vivo activity in Swiss mice infected with this parasite. Three compounds were tested in vitro in duplicate at a concentration of 1.0 to 0.05 mg/mL in a microplate containing 100 larvae in RPMI-1640 medium incubated for 48 h at 37°C and 5% CO. The compound (E)-2-((1,7,7-trimethylbicyclo [2.2.1] heptan-2-ylidene)amino)phenol (C2) presented a minimum larvicidal concentration (MLC) of 0.25 mg/mL and was selected for the subsequent steps. This compound showed 100% cell viability in MLC and adequate bioavailability in computational models. Two subsequent in vivo tests were performed on Swiss mice inoculated with 500 infective eggs through intragastric (IG) intubation, one at 10 days post-inoculation (n=5) and the other at 30 days post-inoculation (n=10). The selected compound (10 mg/kg, via IG) and two controls (albendazole, 40 mg/kg, IG and phosphate buffered saline 0,15M, pH 7,2, via IG) were used for this evaluation. The compound reduced the intensity of infection by 75.7% and 54.8% at 10 and 30 days post inoculation, respectively (p<0.05). The results of this study demonstrate that this compound has potential as an anthelmintic candidate for visceral toxocariasis treatment.

This systematic review and meta-analysis examined 27 studies published between 2003 and 2024 to assess the prevalence of infestation in various animal species in Algeria. Diagnostic methods included liver inspection (16 studies), ELISA (7 studies), coproscopy (4 studies), bile microscopy (1 study), and abattoir data analysis (1 study). For humans, coproscopy and immunoelectrophoresis (IEP) were used in one study in Algiers. Among the 1,006,751 animals examined, 15,868 tested positive, resulting in an overall prevalence of 1.57% (CI 1.55-1.59). Prevalence was higher in the northeastern regions of Algeria (El Tarf, Annaba, and Jijel) at 15.95%, compared to other regions (0.9%-2.95%) (p<0.0001). Cattle showed the highest prevalence (3.91%; CI 3.84-3.98) (p<0.001), followed by sheep (0.42%; CI 0.40-0.44) and goats (0.12%; CI 0.10-0.14). Camels had a prevalence rate of 4%. Trend analysis over 20 years indicated a progressive decrease in prevalence, from 13.29% (2004-2009) to 1.79% (2010-2019) and 1.12% (2020-2024) (p<0.0001). The ELISA method was found to be the most sensitive, revealing a prevalence of 16.40% (CI 15.23-17.57) (true adjusted prevalence is 12.38%) (p<0.0001), significantly higher than liver inspection (1.83%), coproscopy (1.04%), and abattoir data analysis (1.10%). Prevalence increased with animal age across all species. This study clearly shows that fasciolosis in Algeria is most prevalent in the northeast region and that cattle are the high-risk group of animals. As a result, control strategies are urgently needed, targeting cattle in particular in northeast Algeria, to prevent and control this disease and thus reduce Fasciola infection.

Metal pollution is a major global issue in aquatic environments, affecting environmental quality and potentially altering host-parasite dynamics. This study evaluates the buffering role of a larval trematode sp. under experimental conditions to test the effect of copper (Cu) exposure on the survival of the marine snail Snails were collected from intertidal rocky pools over a two-month period from Coloso (23°45'S, 70°28'W), northern Chile, and identified as parasitized or unparasitized. Both groups were then exposed to Cu concentrations (3 and 6 mg/L). Kaplan-Meier curves were used to determine the percentage of survival over time and the respective confidence intervals (CI). A nested ANOVA was conducted to assess whether rediae abundance per snail varied by experiment time, snail status, and Cu concentration. Snail survival was affected by both Cu-concentrations, but the effect was greater at 6 mg/L. At 3 mg/L, 57% (CI: 49.9-66.6%) of unparasitized snails were alive at 192 h, while 56% (CI: 46.6-67.4%) of parasitized snails survived at 216 h. At 6 mg/L, 42% (CI:35-51%) of unparasitized snails survived at 192 h, while 48% of parasitized snails survived at 216 h (CI:39-59%). Regardless of Cu concentration, after 240 h, all unparasitized snails had died, while 15% of parasitized snails remained alive. Dead snails harboured 125±53 rediae, while survivors had 194±73 rediae, with no significant differences between treatments. Our results show that parasitized snails survived longer than unparasitized snails, suggesting a trade-off between parasitism and host survival in polluted environments.

This study investigated the helminths of the mixed invasive population of and , collected during two field trips in Denyshy, Zhytomyr region, Ukraine, in 2023. In total, 67 adult lizards (35 and 32 ) were examined. Molecular and morphological approaches were used to identify the parasites. The analyses revealed six helminth species, including four nematodes (, sp., and Spirurida gen. sp.), one trematode (), and one cestode (). had the highest prevalence, found in cysts located primarily on the liver and in the body cavity of the hosts. The qualitative and quantitative comparative assessment of the helminth community suggests that, due to the introduction of these lizards, most helminth species from their native range have been lost. Additionally, most local helminth species have not yet adapted to parasitising these lizards as normal hosts of their life cycle.

Gymnophallidae is one of the digenean families featuring bivalves as first intermediate hosts. However, the exact bivalve host species remain unknown for most members of this family. Gymnophallids have been one of the targets in our continuous efforts to reveal the diversity of digeneans in the higher north. Here, we focus on , which we found in eiders from various locations in the Arctic and sub-Arctic. Sexual adults (maritae) of can be easily identified because they have a distinctive character: the roughly equal size of the pharynx and the ventral sucker. We also matched them, using DNA markers, with the intramolluscan stages (sporocysts, cercariae, and metacercariae) from the bivalve collected on Spitsbergen. Taken together, we compile the first data on the life cycle of and discuss them in the context of other gymnophallids.

A population of was recovered from inside the body of a live scarab beetle collected from natural forests of Jafar Abad village, Golestan province, and was reported from Iran for the first time. The Iranian isolate of the species is characterized by 1103-1942 μm long females with their vulva at 46.9-57.4% of the body, tail 75-118 μm long, males with spicules 60.0-74.5 μm long, gubernaculum 23.7-32.2 μm long, and infective juveniles measuring 790-985 μm long. Females and males of the recovered population had shorter body when compared with the type population. Molecular identification of the recovered population was performed using the SSU and D2-D3 expansion segments of LSU rDNA, and corresponding phylogenetic trees were reconstructed and discussed. The pathogenicity of the Iranian isolate was evaluated on the larvae and adults of the poplar leaf beetle, , and the larvae of the wax moth, , under laboratory conditions. A suspension of 200 infective juveniles per ml (IJs/ml) of the nematode was most effective against third instar larvae of , causing 75% mortality 72 hours post-exposure. In adults, mortality reached 70% at the same concentration and exposure time. For larvae, caused 50% mortality at 200 IJs/ml within 72 hours post-exposure. The lethal concentration 50 (LC50) values of the nematode were 77.71 and 94.06 IJs/ml for third instar larvae and adults of , respectively, and 217.04 IJs/ml for fifth instar larvae of 72 hours post-exposure at 25°C and 60% relative humidity.

The digenetic trematode is a cosmopolitan parasite that infects various invertebrates and fish hosts, including the blue mussel, , along the northeastern U.S. coast. Despite its impact on mussel fitness and the region's aquaculture, little is known about the genetic diversity and connectivity of in this region. This study provides the first genetic characterization of populations in New England using the D1-D3 region of the 28S ribosomal RNA gene. Bayesian phylogenetic analysis and a haplotype network were used to assess genetic variation and connectivity across six localities in Maine, New York, and southern New England, and to compare these populations to global samples. Our results revealed distinct geographic structuring of haplotypes. The ME1 haplotype, unique to Maine, reflects either recent range expansion or isolation driven by environmental and biogeographic factors, such as Cape Cod's role as a phylogeographic barrier. The most common haplotype, US1, was shared by populations in southern New England, New York, and a single specimen from Tunisia, indicating possible historical or anthropogenic connectivity. Two divergent haplotypes from Mississippi and Chile likely represent misidentifications or cryptic species. These findings support the hypothesis that is likely a cryptic species complex. Molecular evidence suggests connectivity across distant regions, emphasizing the role of host movement in parasite dispersal. Continued genetic studies, particularly from under-sampled regions, are needed to unravel the diversity and biogeography of and its potential impact on declining mussel populations.

This study describes a new species of Diesing, 1961 (Nematoda: Pharyngodonidae) in teiid lizards (Spix, 1895) (Squamata: Teiidae) from a Caatinga morphoclimatic domain in the state of Pernambuco, Brazil. n. sp., like 11 other species of the genus, features males without spicules, females with truncated eggs, and no tail spines. However, the new species is distinguished by a unique set of morphological characteristics, such as males possessing three pairs of caudal papillae, with the first pair precloacal, the second adcloacal, and the third postcloacal (arrangement 1:1:1), the second pair (adcloacal) of papillae having a bifurcated distal end, and females with lateral body alae. Molecular analysis of the 18S rDNA, 28S rDNA, and 18S + 28S concatenated sequences genes reveals that n. sp. clusters with representatives of Pharyngodonidae from the genera Inglis, 1968 and Skrjabin, Schikhobalova & Lagodovska, 1960, forming a basal clade to the clade composed of spp. and Ainsworth, 1990. These are the first phylogenetic assays to include a species of

Iceland is an isolated, sub-Arctic, oceanic island of volcanic origin in the northern North Atlantic. With a limited faunal diversity and being the most northern point in the distributional range for some species, it is an intriguing model region to study parasite biodiversity and biogeography. Since 2006, there has been a history of intense biodiversity discoveries of freshwater trematodes (Trematoda, Digenea), thanks to the use of integrative taxonomic methods. The majority of digeneans (28 out of 41 known) were characterised with molecular genetic methods and morphological analyses, with some of their life-cycle stages and geographical distribution assessed. A surprising diversity has been discovered, comprising species of the families Allocreadiidae, Cyclocoeliidae, Diplostomidae, Echinostomatidae, Gorgoderidae, Plagiorchiidae, Notocotylidae, Schistosomatidae, and Strigeidae. Many of the recorded species complete their life cycles within Iceland, with three snail species (, , ) known as intermediate hosts. No trematodes endemic for Iceland were found; they appear to be generalists with wide geographical ranges dispersed mainly by migratory birds. Interestingly, fish trematodes recorded in Iceland were found in mainland Europe, indicating that they might be dispersed by anadromous fishes, by human activity, or by migratory birds carrying intermediate hosts. The trematode fauna is mainly Palaearctic, with few species recorded in North America. We highlight the ongoing need for precise species identification via integrative taxonomic methods, which is a baseline for any further ecological studies and adequate epidemiological and conservation measures. Also, there is still a need of obtaining well-preserved vouchers of adults for definite species delimitation.

The growth and development of schistosomes are tightly regulated by various receptors throughout their life cycle. Each stage of the parasite inhabits a distinct habitat and responds to different factors that drive its growth and development. With two hosts involved in its life cycle (mammalian and snail), the parasite must go through additional free-living stages to transition between them. Moreover, communication between male and female worms is essential for the maturation of females. The ability of adult schistosomes to survive in human hosts for up to thirty years demonstrates their capacity to efficiently utilize host nutrients for metabolic processes and growth. In , receptors mediate the utilization of growth factors derived from both the parasite itself and the host. Nuclear receptors, in particular, collaborate with other proteins to regulate the expression of genes essential for various developmental functions. Receptors also play a pivotal role in RNA export, which is crucial for the parasite development. Additionally, neurotransmitter receptors are essential for the growth and development of larval stages. This review aims to elucidate the mechanisms by which these receptors regulate cell proliferation, differentiation, and maturation throughout the parasite life cycle. Understanding these processes could provide insights into the role of receptors in development and potentially lead to innovative therapeutic strategies to combat human schistosomiasis.

Equids are infected by a diversity of gastrointestinal nematode parasites, including 64 species of equine strongyle nematodes from19 genera. Despite numerous surveys of horse strongyles worldwide, certain geographic regions and rare species remain understudied. In 1964, a new species of equine strongyle, , was described from a donkey in China. Subsequently, this species was recorded in horses from Kazakhstan and reclassified as (K'ung and Yang, 1964), the only species in this genus. Since then, has not been reported elsewhere, with limited knowledge on its distribution and phylogeny.This study documents the first record of in North America. Adult specimens were recovered from fecal samples of a domestic horse in Alberta, Canada, following treatment with ivermectin. Species identification involved detailed morphological examination, complemented with sequencing of the internal transcribed spacer 1 (ITS1), 5.8S rRNA gene, and the internal transcribed spacer 2 (ITS2) regions of the nuclear genome. Phylogenetic analysis indicated a close evolutionary relationship with species from and genera. Nemabiome ITS2 sequencing of a paired pre-treatment sample also detected the presence of in the studied horse. Re-analysis of public equine nemabiome datasets further detected in feral horses in Alberta, but not in other regions considered. This study expands the known distribution of this rare species and enhances our knowledge of its placement in the phylogeny of equine strongyles. Furthermore, our re-analysis of public nemabiome datasets highlights the value of this approach for studying the global distribution of parasite species.

Species of the genus (Acanthocephala: Polymorphida) mainly parasitize marine mammals and rarely marine birds, and are of veterinary and medical importance due to causing corynosomiasis in wildlife and humans. However, the current knowledge of the mitochondrial genomes and mitogenomic phylogeny of this group remains very insufficient. In the present study, the complete mitochondrial genomes of (von Linstow, 1892) and Zdzitowiecki, 1984 were sequenced and annotated for the first time. Both mitogenomes comprise 12 protein-coding genes (missing ), 22 tRNA genes, and 2 ribosomal RNAs ( and ), plus 2 non-coding regions ( and ). has the largest mitogenome (14,879 bp) of any polymorphid species reported so far, while has the smallest (13,947 bp), except for (Petrochenko, 1949). Comparative mitogenomic analysis also revealed the presence of distinct discrepancies in A + T content and gene rearrangement across the families Polymorphidae, Centrorhynchidae, and Plagiorhynchidae. Moreover, phylogenetic analyses based on the concatenated amino acid sequences of 12 protein-coding genes strongly supported the monophyly of the order Polymorphida and a close affinity between the families Polymorphidae and Centrorhynchidae in Polymorphida. The present mitogenomic phylogeny provides additional evidence for a sister relationship between the genera and and demonstrated that has a closer relationship with than in the genus

A new species of Kritsky, Thatcher & Kayton, 1980, collected from the gills of (Bryconidae) in the Cerrado, in the state of Goiás, Brazil, is described based on morphological and molecular data, based on the mitochondrial cytochrome oxidase subunit 1 () gene region. n. sp. is distinguished from all its congeners by the unique 'bell-shaped' accessory piece in the male copulatory complex. Molecular analysis revealed that the specimens analyzed formed a distinct group from other sequences and that the sequences of showed genetic divergence when compared to n. sp., confirming the molecular distinction between the two species. This study also expands the knowledge of parasitic diversity in the Tocantins-Araguaia River Basin and extends the geographical distribution of the genus The combination of morphological and genetic data was essential for delimiting this new species, highlighting the importance of integrative approaches in understanding the diversity of monogeneans in freshwater fish in Brazil.