Metazoan parasites of Hoplias aff. malabaricus, Trachelyopterus galeatus and Schizodon borellii (Osteichthyes) from the Protected Area and its main tributary, Brazil.

A study of the parasite-host interactions was conducted in the protected area popularly known as the "Refúgio Biológico de Santa Helena" and its tributary, the São Francisco Falso River. For each of the three host species, Schizodon borellii, Hoplias aff. malabaricus, and Trachelyopterus galeatus, 30 fish were collected from 2018 to 2019. A total of 2172 parasites were identified among the three host species. Among these, the Monogenea class had the highest number of species, with 26 taxa, followed by Copepoda with eight taxa, Digenea with six taxa, and Cestoda and Nematoda with one taxon each. Eleven new records of infection/infestation were found among the host species such as Urocleidoides paradoxus, Urocleidoides ramentacuminatus, Rhinoxenus arietinus, Mymarothecioides sp. (Monogenea), Ergasilus cf. bryconis, Lernaea devastatrix, and Brasergasilus sp. (Copepoda) parasitizing S. borellii. Trinigyrus sp., Vancleaveus sp. (Monogenea), Gamispinus diabolicus (Copepoda) present in T. galeatus, and Gamidactylus jaraquensis (Copepoda) present in H. aff. malabaricus. This study contributes to the record of parasite species occurrence in the vicinity of a protected area and helps fill gaps in the knowledge of fish parasitic fauna in the Neotropical region.

Identifying fish eggs and larvae: from classic methodologies to DNA metabarcoding.

Studies involving fish eggs and larvae date back to the end of the nineteenth century. Since then, studies with ichthyoplankton have proved to be an essential tool, generating information for the knowledge of the ichthyofauna and the environmental inventory. Most of these studies reveal the difficulty of obtaining a precise taxonomic identification of the collected materials, making research with ichthyoplankton extremely challenging. With the advent of molecular biology, the use of markers such as COI enabled greater taxonomic precision, helping to understand events involving ichthyofauna. Now we can observe the evolution of the molecular identification tool for ichthyoplankton via DNA barcoding, which has been increasingly used over the last few decades. From 2000 to 2010, we found six publications; from 2011 to 2021, 75 papers were published, and in 2022 four studies. Our survey also showed the accuracy of molecular identification when compared to the taxonomic identification of these. In this review, we show the state of the art of studies that used barcode and DNA metabarcoding to identify fish eggs and larvae in different environments and discuss their importance as the best practice for working with these organisms.

Ichthyofauna of Santa Helena Relevant Ecological Interest Area (REIA), Paraná, Brazil / Ictiofauna da Área de Relevante Interesse Ecológico (ARIE) de Santa Helena, Paraná, Brasil

Abstract The Relevant Ecological Interest Area (REIA), popularly known as "Refúgio Biológico de Santa Helena", is part of the Atlantic Forest Biome and one of the 78 ecoregions mapped by IBAMA as basic unit for planning priorities focused on national biodiversity conservation. Quarterly collections were carried out from November 2017 to November 2019 to inventory the ichthyofauna of this Conservation Unit. Specimens were captured with the aid of gillnets, fishing sieve and seine. In total, 3,919 specimens belonging to two class, eight orders, 27 families and 74 species were sampled. Characiformes and Siluriformes presented the highest species richness; they accounted for 40 (54%) and 17 (23%) species, respectively. Geophagus sveni (181 individuals = 17%), Trachelyopterus galeatus (109 individuals = 10%) and Schizodon borellii (105 individuals = 10%) were the most abundant fish species captured with gillnet. Moenkhausia was the most abundant genus captured with seine and fishing sieve, with emphasis on species Moenkhausia bonita (930 individuals = 33%) and Moenkhausia gracilima (845 individuals = 30%). Moreover, two "endangered" species (Brycon orbignyanus and Pseudoplatystoma corruscans) were registered. Therefore, we present an updated inventory of species belonging to the ichthyofauna of REIA, and it may contribute to future management plans focused on this Conservation Unit.

Resumo A Área de Relevante Interesse Ecológico (ARIE), popularmente conhecida como "Refúgio Biológico de Santa Helena", faz parte do Bioma Mata Atlântica, uma das 78 ecorregiões mapeadas pelo IBAMA como unidade básica de planejamento e prioridades para a conservação da biodiversidade nacional. Foram realizadas coletas trimestrais de novembro de 2017 a novembro de 2019 para inventariar a ictiofauna desta Unidade de Conservação. Os espécimes foram capturados com o auxílio de redes de emalhar, peneira e rede de arrasto. No total, foram amostrados 3.919 exemplares pertencentes a duas classes, oito ordens, 27 famílias e 74 espécies. Characiformes e Siluriformes apresentaram a maior riqueza de espécies; somando um total de 40 (54%) e 17 (23%) espécies, respectivamente. Geophagus sveni (181 indivíduos = 17%), Trachelyopterus galeatus (109 indivíduos = 10%) e Schizodon borellii (105 indivíduos = 10%) foram as espécies de peixes mais abundantes capturadas com rede de espera. Moenkhausia foi o gênero mais abundante capturado com rede de arrasto e peneira, com destaque para as espécies Moenkhausia bonita (930 indivíduos = 33%) e Moenkhausia gracilima (845 indivíduos = 30%). Além disso, duas espécies "ameaçadas" (Brycon orbignyanus e Pseudoplatystoma corruscans) foram registradas. Assim, apresentamos um inventário atualizado das espécies pertencentes à ictiofauna da ARIE, podendo contribuir para futuros planos de manejo voltados para esta Unidade de Conservação.

A New Species of Rhinergasilus Boeger et Thatcher, 1988 (Copepoda: Ergasilidae) from Gills of Astyanax fasciatus (Cuvier, 1819) (Actinopterygii: Characidae).

PURPOSE: To describe a new species of a parasitic copepod, Rhinergasilus digitus n. sp. (Cyclopoida, Ergasilidae), collected from the gills of the red-tailed lambari Astyanax fasciatus (Characiformes, Characidae) in two tributaries of the Jurumirim Reservoir (Upper Paranapanema River), São Paulo State, Brazil: Ribeirão dos Veados and Paranapanema River. METHODS: Fish were collected using multi-panel gills nets. The gill of each fish was washed and examined in a stereo microscope for copepods. The copepods found were stored in 70% ethanol, cleared in lactic acid, and mounted in Hoyer's medium. Drawings were made with the aid of a Leica microscope DMLS equipped with a drawing tube. RESULTS: The new species differs from its congeneric species, Rhinergasilus piranhus (type-species), in having comparatively biggest body size (body length: 535-598 µm in the new species vs. 237-282 µm in R. piranhus); second antennary segment armed with a minute sensillum near middle of inner margin and a row of spinules on outer margin; third exopodal segment of leg 1 with digitiform process; interpodal plates two and three both ornamented with spinules along posterior margin; leg 5 reduced and represented by two unequal setae. CONCLUSIONS: Based on the morphological differences described above, we erected a new species of Rhinergasilus. Rhinergasilus digitus n. sp. is the second ergasilid described from A. fasciatus, as well as it represents the first report of this genus in a characid fish.

A New Genus of Ergasilidae (Copepoda: Cyclopoida) from the Gills of Astyanax fasciatus (Cuvier, 1819) (Actinopterygii: Characidae).

PURPOSE: To describe a new genus and a new species of an ectoparasitic ergasilid (Copepoda, Ergasilidae) parasite of the red-tailed lambari, Astyanax fasciatus, from Jurumirim Reservoir (Upper Paranapanema River), São Paulo State, Brazil. METHODS: The host fish were collected using multi-panel gill nets. The gill of each fish was washed and examined in a stereo microscope for copepods. The copepods found were stored in 70% ethanol, cleared in lactic acid, and mounted in Hoyer's medium. Some specimens were dissected in glycerol medium and then each dissected part was mounted on individual slides. RESULTS: A new genus and a new species of Ergasilidae were described herein. Duoergasilus basilongus n. gen., n. sp. differs from all other ergasilids in having the second and third pair of biramous swimming legs (P2 and P3) each with a 2-segmented endopod, and by its unique maxillary basis, resembling a whip. CONCLUSIONS: The new copepod is the first 'four-legged' ergasilid with all swimming legs having a 2-segmented endopod. Duoergasilus basilongus n. sp. represents the first record of a parasitic copepod on A. fasciatus in Jurumirim Reservoir, as well as its represents the first description to species level of an ergasilid infecting an Astyanax species in Brazil. A key to the 28 accepted genera of Ergasilidae is provided.

Species richness and functional structure of fish assemblages in three freshwater habitats: effects of environmental factors and management.

In this study, the inverted trophic hypothesis was tested in the freshwater fish communities of a reservoir. The distribution of fish species in three freshwater habitats in the Jurumirim Reservoir, Brazil, was examined using both species richness and the relative proportions of different trophic groups. These groups were used as a proxy for functional structure in an attempt to test the ability of these measures to assess fish diversity. Assemblage structures were first described using non-metric multidimensional scaling (NMDS). The influence of environmental conditions for multiple fish assemblage response variables (richness, total abundance and abundance per trophic group) was tested using generalised linear mixed models (GLMM). The metric typically employed to describe diversity; that is, species richness, was not related to environmental conditions. However, absolute species abundance was relatively well explained with up to 54% of the variation in the observed data accounted for. Differences in the dominance of trophic groups were most apparent in response to the presence of introduced fish species: the iliophagous and piscivorous trophic groups were positively associated, while detritivores and herbivores were negatively associated, with the alien species. This suggests that monitoring functional diversity might be more valuable than species diversity for assessing effects of disturbances and managements policies on the fish community.

Karyotype Diversity and Evolutionary Trends in Armored Catfish Species of the Genus Harttia (Siluriformes: Loricariidae).

Most species of the genus Harttia inhabits the headwaters of small tributaries, but some species are restricted to the main channel of some rivers. This feature, combined with limited dispersal ability, leads to the formation of small isolated populations with reduced gene flow. Currently, there are 23 taxonomically defined and recognized species, and 17 of these are found in Brazil, distributed in several hydrographic basins. Despite this diversity, few chromosomal data for the species belonging to this genus are found in the literature. Thus, this study analyzed, by classical and molecular cytogenetics methodologies, the chromosomal diversity of this genus, to discuss the processes that are involved in the evolution and karyotype differentiation of the species of the group. Seven species of Harttia were analyzed: H. kronei, H. longipinna, H. gracilis, H. punctata, H. loricariformis, H. torrenticola, and H. carvalhoi. The chromosomal diversity found in these species includes different diploid and fundamental numbers, distinct distribution of several repetitive sequences, the presence of supernumerary chromosomes in H. longipinna and multiple sex chromosome systems of the type XX/XY1Y2 in H. carvalhoi and X1X1X2X2/X1X2Y in H. punctata. Lastly, our data highlight the genus Harttia as an excellent model for evolutionary studies.

Parasitism by Sphincterodiplostomum musculosum (Digenea, Diplostomidae) metacercariae in the eyes of Steindachnerina insculpta (Characiformes, Curimatidae).

New occurrences and effects of parasitism by metacercariae in fish eyes have recently been discussed in many studies. The aim of the present study was to evaluate the infection levels of the eye flukes Sphincterodiplostomum musculosum Dubois, 1936 (metacercariae) in Steindachnerina insculpta (Fernádez-Yépez, 1948) from three ecosystems under the influence of the Jurumirim reservoir (Paranapanema, Taquari and Veados Rivers). A total of 174 fish specimens were sampled between April 2011 and April 2012. There were high levels of infection by S. musculosum metacercariae in the eyes of S. insculpta from all the sampled ecosystems, thus presenting broad geographical distribution. The histological analyses revealed that the metacercariae were apparently lodged behind the retina. The smaller fish from the Taquari River were less parasitized by metacercariae than the adults. This pattern can be explained by the cumulative effect of parasitism, as demonstrated by the positive correlation between the abundance of metacercariae and fish body size.

Parasitism by Sphincterodiplostomum musculosum (Digenea, Diplostomidae) metacercariae in the eyes of Steindachnerina insculpta (Characiformes, Curimatidae) / Parasitismo por metacercárias de Sphincterodiplostomum musculosum (Digenea, Diplostomidae) nos olhos de Steindachnerina insculpta (Characiformes, Curimatidae)

New occurrences and effects of parasitism by metacercariae in fish eyes have recently been discussed in many studies. The aim of the present study was to evaluate the infection levels of the eye flukes Sphincterodiplostomum musculosum Dubois, 1936 (metacercariae) in Steindachnerina insculpta (Fernádez-Yépez, 1948) from three ecosystems under the influence of the Jurumirim reservoir (Paranapanema, Taquari and Veados Rivers). A total of 174 fish specimens were sampled between April 2011 and April 2012. There were high levels of infection by S. musculosum metacercariae in the eyes of S. insculpta from all the sampled ecosystems, thus presenting broad geographical distribution. The histological analyses revealed that the metacercariae were apparently lodged behind the retina. The smaller fish from the Taquari River were less parasitized by metacercariae than the adults. This pattern can be explained by the cumulative effect of parasitism, as demonstrated by the positive correlation between the abundance of metacercariae and fish body size.

Novas ocorrências e efeitos do parasitismo por metacercárias em olhos de peixe têm sido recentemente discutidas em muitos estudos. O objetivo deste estudo foi avaliar os níveis de infecção dos vermes de olho Sphincterodiplostomum musculosum Dubois, 1936 (metacercárias) em Steindachnerina insculpta (Fernádez-Yépez, 1948) de três ecossistemas influenciados pelo reservatório de Jurumirim (Rios Paranapanema, Taquari e Veados). Um total de 174 espécimes de peixes foi amostrado de Abril/2011 a Abril/2012. Metacercárias de S. musculosum mostraram altos níveis de infecção nos olhos de S. insculpta em todos os ecossistemas amostrados apresentando ampla distribuição geográfica. As análises histológicas revelaram que, aparentemente, estas metacercárias estavam alojadas por trás da retina. Os peixes menores do rio Taquari estavam menos parasitados por metacercárias do que os adultos. Esse padrão pode ser explicado pelo efeito cumulativo de parasitismo, evidenciado pela correlação positiva entre a abundância de metacercárias e tamanho do corpo dos peixes.

Influence of cage farming on feeding and reproductive aspects of Pimelodus maculatus Lacépède, 1803 (Siluriformes: Pimelodidae) in the Chavantes reservoir, Brazil / Influência de uma piscicultura em tanques-rede sobre a alimentação e aspectos reprodutivos de Pimelodus maculatus Lacépède, 1803 (Siluriformes: Pimelodidae) no reservatório Chavantes, Brasil

This study evaluated the diet and reproductive aspects of the population of Pimelodus maculatus around net cage fish farming in order to assess the possible impacts of this activity. Monthly collections were performed from March 2008 to February 2009 on two populations: one close to the net cages (NC) and one from an area not influenced by these cages denominated the "reference site" (RS). Results of the Alimentary Index (AI), Gonadosomatic Index (GSI), reproductive potential and histological analysis were obtained for both NC and RS populations. The population from NC used leftover food (ration) that escapes from net cages as the main food item (99.3%). For the RS population, the detritus item was the more important food source (51.7%). The Detrended Correspondence Analysis (DCA) showed that the use of food resources was different between the two sites. The reproductive period of the species (indicated by the GSI) revealed that the population of the NC showed an extended reproductive period compared to RS. The histology of the ovaries indicated that the specimens in the NC were spawning capable. This study indicates that fish farming activities influence the species P. maculatus in the Chavantes reservoir by adding a new resource to the food web.

O objetivo deste estudo foi avaliar a dieta e os aspectos reprodutivos da população de Pimelodus maculatus residentes ao redor de tanques-rede. Os peixes foram coletados mensalmente, de março/2008 a fevereiro/2009, a partir de duas populações: uma próxima ao ambiente de tanques-rede (NC) e a outra em uma área não influenciada pelos tanques-rede, denominada área de referência (RS). As análises do Índice Alimentar (AI), Índice Gonadossomático (IG), Potencial Reprodutivo e Histologia das gônadas foram realizadas para as populações das duas áreas amostradas. As populações de NC utilizaram-se de restos de ração que escapam dos tanques-rede, como principal fonte alimentar (99,3%). Para a população do RS, os detritos foram a fonte mais importante (51,7%). A análise de Correspondência Destendenciada (DCA) mostrou diferenças na utilização dos recursos alimentares entre as duas populações. O período reprodutivo das espécies (indicado pelo IG) mostrou que a população do NC apresentou maior período reprodutivo em relação às populações do RS. A histologia dos ovários indicou que os espécimes de NC estavam aptos à desova. Este estudo adverte que as atividades de piscicultura influenciam a referida espécie na represa de Chavantes pela adição de um novo recurso para a cadeia alimentar.

Monogeneans (Dactylogyridae) parasitizing gills of Salminus hilarii from a Neotropical reservoir, Brazil / Monogenéticos (Dactylogyridae) parasitando brânquias de Salminus hilarii de uma represa Neotropical, Brasil

With the aim of creating an inventory of the metazoan gill parasites of Salminus hilarii in the Taquari River, state of São Paulo, Brazil, five species of monogeneans (Anacanthorus contortus, A. bicuspidatus, Annulotrematoides parisellei, Jainus iocensis and Tereancistrum arcuatus) are reported the first time for this host. A total of 28 fish were sampled quarterly between April 2011 and January 2012, with 10 hosts in a lentic ecosystem and 18 in a lotic ecosystem. Quantitative ecological descriptors (prevalence, intensity of infestation and abundance) were calculated for the purpose to comparing the two ecosystems sampled (lentic and lotic ecosystems). However, no quantitative difference between the lentic and lotic ecosystems was observed. The present study has made available a checklist for species of the genus Anacanthorus and their hosts and geographical distribution in the Neotropical region up to the present time.

Com o objetivo de inventariar os metazoários parasitos de brânquias de Salminus hilarii do rio Taquari, estado de São Paulo, Brasil, cinco espécies de monogenéticos (Anacanthorus contortus, A. bicuspidatus, Annulotrematoides parisellei, Jainus iocensis, e Tereancistrum arcuatus) foram registradas pela primeira vez para o presente hospedeiro. Um total de 28 peixes foi amostrado trimestralmente entre abril/2011 e janeiro/2012, com 10 hospedeiros no ecossistema lêntico e 18 no ecossistema lótico. Os descritores ecológicos quantitativos (prevalência, intensidade de infestação e abundância) foram calculados com o objetivo de comparar os dois ecossistemas amostrados (ecossistema lêntico versus ecossistema lótico). No entanto, nenhuma diferença quantitativa desses foi verificada entre os ecossistemas lêntico e lótico. O presente estudo disponibiliza uma lista de espécies do gênero Anacanthorus, os hospedeiro e distribuição geográfica na região Neotropical até o presente momento.

Helminths of Steindachnerina insculpta in two distinct stretches of the Taquari River, state of São Paulo, Brazil / Helmintos de Steindachnerina insculpta em dois trechos distintos do rio Taquari, Estado de São Paulo, Brasil

The purpose of this study was to evaluate the helminth fauna of Steindachnerina insculpta in the Taquari River, a tributary of the Jurumirim reservoir in the state of São Paulo, and to investigate whether some helminth species may act as a bioindicator of environmental impact. The host fish sample was composed of 60 specimens, with 30 individuals sampled in a lotic stretch and 30 in a lentic stretch. The following were found: the monogeneans Anacanthoroides mizelli, Diaphorocleidus kabatai, Urocleidoides sp. and Euryhaliotrema chaoi; the digenean Sphincterodiplostomum musculosum and unidentified metacercariae; the nematode Travnema travnema and unidentified larvae; and the acanthocephalan Gorytocephalus plecostomorum. The total prevalence of monogeneans (z = 3.14; p = 0.002) and A. mizelli (z = 3.879; p ≤ 0.001), as well as the mean abundance of total monogeneans (U = 642.0; p ≤ 0.001) and A. mizelli (U = 623.5; p ≤ 0.001), were higher in the lentic stretch. Steindachnerina insculpta and its monogeneans comprise a potential group that could be used to investigate environmental impact, as demonstrated in this study.

O objetivo desde estudo foi avaliar a helmintofauna de Steindachnerina insculpta no rio Taquari, um tributário do reservatório de Jurumirim, estado de São Paulo, e verificar se alguma espécie pode agir como bioindicadora de impacto ambiental. A amostragem de peixes foi composta de 60 espécimes, com 30 indivíduos amostrados no trecho lótico e 30 no trecho lêntico. Foram encontrados os monogenóides: Anacanthoroides mizelli, Diaphorocleidus kabatai, Urocleidoides sp. e Euryhaliotrema chaoi; o digenético Sphincterodiplostomum musculosum e metacercárias não identificadas, o nematoide Travnema travnema e larvas não identificadas; e o acantocéfalo Gorytocephalus plecostomorum. A prevalência total de monogenóides (z = 3,14; p = 0,002) e A. mizelli (z = 3,879; p ≤ 0,001) e também a abundância média de monogenóides total (U = 642,0; p ≤ 0,001) e A. mizelli (U = 623,5; p ≤ 0,001) foram maiores no trecho lêntico. Steindachnerina insculpta e seus monogenóides compõem um grupo em potencial que pode ser usado para investigar impactos ambientais, como mostrado neste estudo.

Occurrence of Braga cigarra (Cymothoidae) parasitizing Galeocharax knerii (Characidae) from affluents of Jurumirim reservoir, Brazil / Ocorrência de Braga cigarra (Cymothoidae) parasitando Galeocharax knerii (Characidae) de afluentes da represa de Jurumirim, Brasil

The occurrence of the cymothoidae Braga cigarra is reported parasitizing the oral cavity of freshwater fish Galeocharax knerii from Veados, Paranapanema and Taquari Rivers, affluent of the Jurumirim Reservoir, State of São Paulo, Brazil is reported. The isopod species were identified based on the multilaminar pleopods, narrow pleon and short pleotelson in females. The overall prevalences of isopods were 31.7%, 7.7% and 5.7%, respectively, in the Paranapanema, Veados and Taquari Rivers. This note contributes to the knowledge of the geographical distribution and fauna of parasite crustaceans known to date in these important ecosystems.

Foi registrada a ocorrência do cymothoidae Braga cigarra parasitando a cavidade bucal do peixe de água doce Galeocharax knerii capturado nos rios Veados, Paranapanema e Taquari, afluentes da represa de Jurumirim, Estado de São Paulo, Brasil. As espécies de isópodas foram identificadas com base nos pleópodos multilaminares, abdômen estreito e pleotelson curto nas fêmeas. As prevalências totais de isópodos foram 31,7%, 7,7% e 5,7%, respectivamente, nos rios Paranapanema, Veados e Taquari. Essa nota contribui com o conhecimento da distribuição geográfica e da fauna de crustáceos parasitas conhecidas até a presente data nesses importantes ecossistemas aquáticos.

Occurrence of Braga cigarra (Cymothoidae) parasitizing Galeocharax knerii (Characidae) from affluents of Jurumirim reservoir, Brazil.

The occurrence of the cymothoidae Braga cigarra is reported parasitizing the oral cavity of freshwater fish Galeocharax knerii from Veados, Paranapanema and Taquari Rivers, affluent of the Jurumirim Reservoir, State of Sao Paulo, Brazil is reported. The isopod species were identified based on the multilaminar pleopods, narrow pleon and short pleotelson in females. The overall prevalences of isopods were 31.7%, 7.7% and 5.7%, respectively, in the Paranapanema, Veados and Taquari Rivers. This note contributes to the knowledge of the geographical distribution and fauna of parasite crustaceans known to date in these important ecosystems.

Helminths of Steindachnerina insculpta in two distinct stretches of the Taquari River, state of São Paulo, Brazil.

The purpose of this study was to evaluate the helminth fauna of Steindachnerina insculpta in the Taquari River, a tributary of the Jurumirim reservoir in the state of São Paulo, and to investigate whether some helminth species may act as a bioindicator of environmental impact. The host fish sample was composed of 60 specimens, with 30 individuals sampled in a lotic stretch and 30 in a lentic stretch. The following were found: the monogeneans Anacanthoroides mizelli, Diaphorocleidus kabatai, Urocleidoides sp. and Euryhaliotrema chaoi; the digenean Sphincterodiplostomum musculosum and unidentified metacercariae; the nematode Travnema travnema and unidentified larvae; and the acanthocephalan Gorytocephalus plecostomorum. The total prevalence of monogeneans (z = 3.14; p = 0.002) and A. mizelli (z = 3.879; p ≤ 0.001), as well as the mean abundance of total monogeneans (U = 642.0; p ≤ 0.001) and A. mizelli (U = 623.5; p ≤ 0.001), were higher in the lentic stretch. Steindachnerina insculpta and its monogeneans comprise a potential group that could be used to investigate environmental impact, as demonstrated in this study.

Monogeneans (Dactylogyridae) parasitizing gills of Salminus hilarii from a Neotropical reservoir, Brazil.

With the aim of creating an inventory of the metazoan gill parasites of Salminus hilarii in the Taquari River, state of São Paulo, Brazil, five species of monogeneans (Anacanthorus contortus, A. bicuspidatus, Annulotrematoides parisellei, Jainus iocensis and Tereancistrum arcuatus) are reported the first time for this host. A total of 28 fish were sampled quarterly between April 2011 and January 2012, with 10 hosts in a lentic ecosystem and 18 in a lotic ecosystem. Quantitative ecological descriptors (prevalence, intensity of infestation and abundance) were calculated for the purpose to comparing the two ecosystems sampled (lentic and lotic ecosystems). However, no quantitative difference between the lentic and lotic ecosystems was observed. The present study has made available a checklist for species of the genus Anacanthorus and their hosts and geographical distribution in the Neotropical region up to the present time.