Vanessa Doro Abdallah

Anacanthorus is one of the most diverse genera of monopisthocotyl parasites associated with Neotropical Characiformes, particularly serrasalmid fishes. This study aimed to inventory the monopisthocotyl parasites of serrasalmid fish from the Lower São Francisco River, northeastern Brazil. Twenty-nine specimens of Pygocentrus nattereri were collected, and their parasites were examined using standard morphological methods. Our results allowed the description of Anacanthorus penedensis n. sp., supported by morphological and molecular data, and the assessment of its phylogenetic relationships within the Dactylogyridae using partial 28S rDNA sequences. Additionally, previously described monopisthocotyls are reported, including Anacanthorus reginae , Amphithecium falcatum , and Enallothecium aegidatum , whereas Rhinoxenus sp. was identified to the genus level and another dactylogyrid remained unidentified. Anacanthorus penedensis n. sp. can be distinguished from its congeners by having an accessory piece comprising two distinct expansions: a submedial expansion extending to the distal region and a conspicuous laminar subterminal expansion originating from one of the margins of the shaft, with a hooked acute tip, as well as by the relative lengths of the male copulatory organ and the accessory piece. Phylogenetic analyses of 28S rDNA sequences, based on maximum likelihood and Bayesian inference, placed the new species within the genus Anacanthorus and supported the monophyly of the group based on the dataset used in the present study. These findings reinforce the need for future integrative taxonomic studies that combine complementary lines of evidence for species delimitation and suggest the diversity of Anacanthorus remains underestimated.

El XIII Congreso Internacional de Parasitología Neotropical (COPANEO 2025) se celebró del 20 al 24 de octubre de 2025 en Maceió, en el estado de Alagoas, Brasil, bajo el lema “Los desafíos de la parasitología ante el cambio climático y sus impactos ambientales”. El evento reunió a más de 600 investigadores, profesores y estudiantes de 22 países de América, Europa y el Caribe. El programa científico incluyó ocho simposios especializados, organizados según su edición: el I Simposio sobre Acantocéfalos Neotropicales, el II Simposio sobre Parasitismo Intestinal y el II Simposio sobre Fitosanidad Neotropical, seguidos por el III Simposio Una Salud, el III Simposio sobre Leishmaniasis en el Neotrópico, el III Simposio Neotropical sobre Enfermedad de Chagas y el III Simposio sobre Dirofilariasis y Angiostrongilosis en el Neotrópico, culminando con el VI Simposio sobre Ictioparasitología Neotropical. Además, se ofrecieron seis cursos cortos teóricos y teórico-prácticos, junto con 32 conferencias magistrales impartidas por especialistas de países como Perú, Brasil, Uruguay, Colombia y España, así como 26 mesas redondas con 26 participantes. En total, se abordaron 22 áreas temáticas desde una perspectiva interdisciplinaria y de Una Salud, fomentando el intercambio científico y fortaleciendo las redes de colaboración internacional en el contexto del cambio ambiental global.

Phyllodistomum pepirense n. sp. is described from the urinary bladder of Hoplias malabaricus (Bloch, 1794), sampled in the Jacaré-Pepira River in São Paulo state, Brazil. The isolates of the new species were recovered as a monophyletic group in the phylogenetic analysis of the 28S rRNA gene, which showed the new species as the sister taxa of Phyllodistomum virmantasi Pinacho-Pinacho, Sereno-Uribe, Hernández-Orts, García-Varela & Pérez-Ponce de León, 2021, a species sampled from an eleotrid fish in Southeastern Mexico. The new species differs morphologically from P. virmantasi by having a larger body size, slightly lobed testes and ovary, a mostly intercaecal uterus, slightly diverticulated caeca, and vitelline masses irregularly shaped. The new species is also readily distinguished from other species of Phyllodistomum Braun, 1899 reported from freshwater fishes in Brazil – namely, P. rhamdiae Amato & Amato, 1993 and P. spatula Odhner, 1902. The new species is herein described based on morphological characteristics, molecular data from D1–D3 domains of the 28S rRNA gene, host association, and geographical distribution.

Oncoceratiumn. gen. is proposed to accommodate Oncoceratium amphidactylumn. gen. n. sp. (Monogenoidea, Gyrodactylidae). Although the proposed genus is monotypic, the differences presented in the diagnosis clearly establish it as distinct from species from other genera, such as Gyrodactylus von Nordmann, 1832 and especially those that occur exclusively in the Neotropical region. The new genus is diagnosed by the presence of a bulbous male copulatory organ, with one row of spinelets of similar sizes and shapes, while the only spine usually found in the gyrodactylids is absent or not differentiated; a haptor with anchors presenting points folded outwards, and superficial and deep roots continuous and indistinguishable; the absence of a deep bar; and hooks in two bilateral clusters of eight hooks. Oncoceratium amphidactylumn. gen. n. sp. is described from the tamboata fish, Hoplosternum littorale (Hancock) (Callichthyidae), and is characterized by the presence of a pair of horn-shaped anchors with the point turned outwards, a superficial bar shield and absent deep bar, hooks disposed in bilateral lobes, and a MCO with no spine or with a row with large spinelets visible in place of the spine. In addition to the morphological features, distance analysis and Bayesian inference, based on 5.8s and partial ITS2, support placing the new species in a new genus, and not including it in a cluster of species of Gyrodactylus and near to Gyrodactyloides bychowskii Albova, 1948, Ieredactylus rivuli Schelkle et al., 2011 and Laminiscus gussevi (Bychowsky & Polyansky, 1953) Palsson & Beverely-Burton, 1983.

Here, we evaluate the relationships between the infestation rates of five monogenean parasites species with the dry and wet seasons, with the organic and inorganic parameters of the water of two rivers: the Jacaré-Pepira and Jacaré-Guaçú, and with the condition factors of its fish hosts: Serrasalmus maculatus and Astronotus crassipinnis, in the state of São Paulo, southeastern Brazil. Fish were collected between January and December 2017. Anacanthorus serrasalmi, Amphithecium speirocamarotum and Gussevia asota had higher abundance rates (Student’s t test, p ≤ 0.05) in the wet season. Gussevia asota had its abundance negatively correlated to nitrate in the Jacaré-Pepira River and with total nitrogen and potassium in the Jacaré-Guaçú River. Regarding the fish hosts condition factors, was observed a positive correlation with the abundances of G. asota in the Jacaré-Guaçú River, and with A. serrasalmi in the Jacaré-Pepira River. In general, wet season favored an increasing in the infestation rates of the monogeneans parasites in their host species, mainly in the river considered as the most polluted, the Jacaré-Guaçú River. Of the five parasites species analyzed in this study, only Gussevia astronoti and Rhinoxenus piranhus had no interaction with seasonality, river water variables, or fish host condition factors. On the other hand, G. asota had interactions both with water parameters (nitrate and total nitrogen) and with the hosts condition factors, which reflected in the abundance and intensity rates, showing itself as a species sensitive to changes in the environment and, therefore, that can be considered as a bioindicator organism.

Raphidascarid nematodes have been the focus of several studies, mainly due to the zoonotic potential of some species, even though the cases are underreported. Due to the difficulty in identifying their larvae, the use of diagnostic techniques involving morphological and molecular analyses has grown in the last 20 years. The present study had as objective the morphological and molecular characterization of the L3 larval types of Hysterothylacium collected in Pomatomus saltatrix and Pagrus pagrus from the Brazilian coast, close to the municipality of Santos, State of São Paulo. Twenty specimens of P. saltatrix were necropsied and Hysterothylacium type V (n = 257) and Hysterothylacium type X (n = 5) larvae were found. Five specimens of P. pagrus were necropsied and all were parasitized by Hysterothylacium type V larvae. The analyses showed a genetic proximity relationship between Hysterothylacium types V with other Hysterothylacium V and with H. deardorffoverstreetorum, although this is a species inquirenda. Haplotypes for Hysterothylacium type X found in the present study formed a monophyletic group with other Hysterothylacium X, H. amoyense, and H. zhoushanense. Through this study, new hosts and localities were registered for Hysterothylacium type V and Hysterothylacium type X.

We recorded the parasitic fauna of Hoplias malabaricus in a Neotropical River from southeastern Brazil, the Jacaré-Pepira River, in the Tietê-Batalha River Basin. The objective of this study was to inventory the composition of the parasitic fauna of H. malabaricus collected, through ecological and biodiversity approaches. A total of 30 specimens of H. malabaricus were collected in 2018 using fishing nets. Parasites were prevalent in 96.6% of the hosts, with 710 parasites specimens collected, divided into 22 species from 4 different taxa (i.e., Monogenea, Digenea, Nematoda, and Acanthocephala). This was the first survey about the parasitic fauna of H. malabaricus in this river, where three species are new records for this host (i.e., Gussevia sp. 1, Gussevia sp. 2, and Raphidascaris sp.). All species found are new records for the Jacaré-Pepira River, which together with all the data obtained in the study, collaborates to increase knowledge and understanding of the global fish parasite biodiversity.

Purpose We describe two new species of Myxobolus (Myxobolidae) found parasitizing Mugil curema from two locations in Brazil: Myxobolus curemae n. sp. from gill arch and rays and Myxobolus maceioensis n. sp. from gill lamellae. Methods We based the descriptions on myxospore morphology, histology, and small-subunit ribosomal DNA sequences. Results Myxospores of the two new species had similar morphology and morphometry but differed in spore body width and length, and ssrDNA sequences differed by 10.5%. These data supported the diagnosis of the parasites as distinct and novel species. The phylogenetic analysis showed a subclade formed by species that parasitize Mugiliformes, with M. maceioensis n. sp. as a sister species of Myxobolus episquamalis and Myxobolus bizerti, while there is a group of six species that are sister related to M. curemae n. sp. Our analysis was consistent with previous studies suggesting that orders of the hosts are strongly correlated with phylogenetic signals in the Myxobolidae. Conclusions Myxobolus curemae n. sp. and M. maceioensis n. sp. are new species identified parasitizing M. curema.

A new species of Phanerothecium Kritsky & Thatcher, 1977 (Oogyrodactylidae Harris, 1983) is described from locariid fish from southeast Brazil. Phanerothecium macrosomum n. sp. (Oogyrodactylidae) is described from the body surface of Hypostomus regani (Ihering, 1905) (Loricariidae). It is characterized by an armed male copulatory organ containing spines of different size from proximal to distal extremity, short peduncle and robust haptor.

A total of 53 tamboatás, Hoplosternum littorale, from the Batalha River, São Paulo, southeastern Brazil, were examined between February 2014 to December 2016. Seventeen species of parasites were identified, and 961 specimens were collected . The richness of each community varied from one to seven species of parasites per fish. The metacercariae of Diplostomum lunaschiae showed higher prevalence and mean abundance, being the core species. Gyrodactylus sp. obtained a higher mean intensity value. Aporocotylidae gen. sp. showed a significant negative correlation between its abundance and the standard host weight and length, while Spiroxys sp. showed a significant negative correlation between its abundance and the host weight. Batalha River has importance as a maintainer of local biodiversity with a relevant contribution to the knowledge of freshwater biodiversity in the State of São Paulo. Gyrodactylidae gen. sp., A. mordax, Aporocotylidae gen. sp., D. lunaschiae, Diplostomidae gen. sp. 1, Contracaecum sp., D. renale, Porrocaecum sp., Pseudocapillaria sp. 1, Pseudocapillaria sp. 2, S. contortus, Oligobdella sp., and L. cyprinacea are parasites mentioned for the first time in H. littorale. Aporocotylidae gen. sp., Gyrodactylidae gen. sp., and Oligobdella sp. are new species in process of taxonomic description by the authors of the present study.