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The Neotropical region hosts 4225 freshwater fish species, ranking first among the world's most diverse regions for freshwater fishes. Our NEOTROPICAL FRESHWATER FISHES data set is the first to produce a large-scale Neotropical freshwater fish inventory, covering the entire Neotropical region from Mexico and the Caribbean in the north to the southern limits in Argentina, Paraguay, Chile, and Uruguay. We compiled 185,787 distribution records, with unique georeferenced coordinates, for the 4225 species, represented by occurrence and abundance data. The number of species for the most numerous orders are as follows: Characiformes (1289), Siluriformes (1384), Cichliformes (354), Cyprinodontiformes (245), and Gymnotiformes (135). The most recorded species was the characid Astyanax fasciatus (4696 records). We registered 116,802 distribution records for native species, compared to 1802 distribution records for nonnative species. The main aim of the NEOTROPICAL FRESHWATER FISHES data set was to make these occurrence and abundance data accessible for international researchers to develop ecological and macroecological studies, from local to regional scales, with focal fish species, families, or orders. We anticipate that the NEOTROPICAL FRESHWATER FISHES data set will be valuable for studies on a wide range of ecological processes, such as trophic cascades, fishery pressure, the effects of habitat loss and fragmentation, and the impacts of species invasion and climate change. There are no copyright restrictions on the data, and please cite this data paper when using the data in publications.

Corydoras is the richest genus of Corydoradinae, and many of its species have not been identified to date. We characterized Corydoras carlae and Corydoras sp. by performing cytogenetic, morphometric, and molecular analyses to facilitate correct identification and species delimitation and contribute an understanding of the evolutionary process of this group of fish. Individuals of C. carlae were collected in the Florido River, a tributary of the Iguassu River upstream of Iguassu Falls, and individuals of Corydoras sp. were collected in the Poco Preto River, a tributary of the Iguassu River downstream of Iguassu Falls. Corydoras sp. presented an extra rDNA 5S marker in an interstitial position on the short arm of one of the chromosomes of the submetacentric pair 15. Mitochondrial (COI) and nuclear (RAG1) sequences were efficient in discriminating C. carlae and Corydoras sp. Both species had exclusive haplotypes, which suggests the absence of gene flow between species. Furthermore, species delimitation analysis (GMYC and ABGD) suggested two MOTUs for Corydoras specimens from the Iguassu River. Differences in morphometric proportions were also observed. Considering the data gathered in this study, C. carlae and Corydoras sp. comprise distinct evolutionary lineages that are probably undergoing a recent speciation process.

Cichlid fishes use their vision for recognition of other fishes, feeding, and in habitat selection. Neotropical cichlids can be found in a range of different habitats differing in their light regimes, and therefore it is interesting to determine if this is associated with molecular variation of genes responsible for expressing visual pigments. Here, we studied codon variation of the LWS gene in cichlids from South America, and compared it with the variation among species from the African Great Lakes. Partial fragments of this gene were sequenced, including spectral tuning sites. There were notable differences in codons under selection between Neotropical and African cichlids, with Neotropical species exhibiting an overall higher genetic variation than African species, but weaker positive selection. This study provides novel data that contributes to our understanding of the evolution of the visual system in Neotropical cichlids.

The delimitation of conservation units may be supported by information on compositional (taxonomic), functional, and phylogenetic diversity of a given locality or region. In this context, systematic conservation planning and key biodiversity areas are promising approaches for biodiversity protection. Factors such as species representativeness and exclusivity may be used to identify geographical distribution patterns and select relevant areas for conservation at a local scale. This study aims to identify areas with rare and restricted fish species in mountain streams in Southern Brazil, using a method that unites ecological and biogeographical approaches. Seven river basins and 152 mountain streams in Southern Brazil were sampled to obtain data on the occurrence and abundance of 115 fish species. The rarity status of each species was determined and endemicity analysis was used to find areas of restricted species (ARS) with three cell sizes. Using larger cells, continuous areas were identified and supported by a higher proportion of rare fish species. Using smaller cells, discontinuous areas were identified within each of the river basins, where rare and endemic fish species occur. Most of the smaller areas relevant for protecting fish fauna were located outside of conservation units. Fundamental areas were selected for the protection of fish species in mountain streams in Southern Brazil. Both the method proposed and the areas with rare and restricted fish species identified may be used to support systematic conservation planning and to delimit new priority areas for conservation.

In this paper, we investigated composition and trait turnover among fish assemblages in reservoirs distributed across major Brazilian basins, in order to contrast taxonomic and functional turnover and to investigate their respective drivers. We investigated the hypothesis that reservoir assemblages present, on a continental scale, divergent species compositions but with a similar set of traits. Species lists and functional traits were compiled from 79 reservoirs located in the Amazon, Sao Francisco, Parana and Atlantic basins. We observed considerable variation in species and trait composition among reservoirs, with higher intra-basin similarity. Taxonomic turnover ranged between 0 and 1 (0.44 ± 0.22 SD), and functional turnover between 0 and 0.91 (0.37 ± 0.19); functional turnover correlated positively with taxonomic turnover, but showed lower values. Observed functional turnover values did not differ from null expectations, indicating lack of functional convergence. We detected significant effects of basin, longitude, latitude and elevation on turnover values, and the presence of non-native species was associated with either homogenization or differentiation patterns. Our results indicated that fish composition is heterogeneous among impoundments, providing little support to the hypothesis that reservoir assemblages are homogenized on a continental scale. Species and trait composition probably respond to multiple spatial, environmental and biogeographic factors.

Cladistic biogeography is an evolutionary biogeographic approach that infers area relationships by comparing area cladograms derived from different phylogenetic hypotheses. The South American freshwater ichthyofauna is enriched by an extraordinary number of marine-derived lineages, presenting its own phylogenetic and biogeographic patterns. Here, we performed a Brooks Parsimony Analysis (BPA) with the latest phylogenetic proposals for Anablepidae to compare hypotheses about the historical relationships among areas previously recognized based on fish species from the Neotropical region. We found that the area relationships for Anablepidae are in accordance with the pattern evidenced for other marine-derived lineages. The general area cladogram obtained shows a three-area relationship pattern, where freshwater is the sister group of Pacific + Atlantic marine areas. Within the freshwater clade, Southern Brazil + Uruguay River basin and Northwestern Argentina + Midwestern Argentina form two clades. Vicariance, dispersal, and extinction events related to Miocene and Quaternary marine transgressions and ancient connections between the Iguacu and Upper Uruguay River basins supported the historical relationships among areas proposed here. Our results may be applied to patterns shown by other marine-derived lineages, as well as other freshwater organisms not necessarily having marine origins.

Made available in DSpace on 2020-12-10T19:51:55Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-03-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Araucaria Foundation (Fundacao Araucaria de Apoio e Desenvolvimento Cientifico e Tecnologico do Estado do Parana) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Astyanax is a species-rich, non-monophyletic genus composed of several supraspecific taxa that are poorly delimited. The Astyanax fasciatus complex is one of these taxa and shows high taxonomic complexity. To elucidate the evolutionary history of the A. fasciatus complex from southern South America, we conducted cytogenetic, molecular and morphological analyses in specimens from the Uruguay River basin. Cytogenetic characters demonstrated two closely related operational taxonomic units: Astyanax sp. 1 (8m+22sm+10st+6a), Astyanax sp. 2 (8m+24sm+10st+4a) and natural hybrids (8m+23sm+8st+5a). 5S ribosomal DNA sites were found in two pairs of m chromosomes and one pair of a chromosomes in Astyanax sp. 1, two pairs of a chromosomes and one pair of m chromosomes in Astyanax sp. 2, and three m chromosomes and three a chromosomes in hybrids. As51 sites were found in three chromosomes in Astyanax sp. 1 and in five chromosomes in Astyanax sp. 2 and hybrids. Mitochondrial sequence analyses did not separate the two units and hybrids. Morphological analyses revealed differences between Astyanax sp. 2 and hybrids. This secondary contact with gene flow between lineages that diverged long ago might slow or reverse the differentiation/speciation process. These results help us to understand the evolutionary history of this highly complex clade of Astyanax in southern South America. Univ Estadual Oeste Parana, Ctr Ciencias Biol & Saude, Cascavel, Parana, Brazil Univ Estadual Maringa, Posgrad Biol Comparada, Maringa, Parana, Brazil Univ Estadual Maringa, Nucleo Pesquisas Limnol Ictiol & Aquicultura NUPE, Maringa, Parana, Brazil Univ Estadual Maringa, Dept Biol, Maringa, Parana, Brazil Univ Estadual Paulista, Inst Biociencias, Dept Morfol, Lab Biol & Genet Peixes, Botucatu, SP, Brazil Univ Estadual Oeste Parana, Grp Pesquisas Recursos Pesqueiros & Limnol GERPEL, Pos Grad Recursos Pesqueiros & Engn Pesca, Pos Grad Conservacao & Manejo Recursos Nat, Toledo, Parana, Brazil Univ Estadual Paulista, Inst Biociencias, Dept Morfol, Lab Biol & Genet Peixes, Botucatu, SP, Brazil

A new species of Cambeva endemic to the Rio Ivaí basin, Upper Paraná basin, is described combining morphological and molecular data. This new species is distinguished from all congeners by characters related to the number of pectoral-fin rays, to the colour pattern of the dorsal and lateral surface of the body, to the presence of diffuse blotches in the ventral surface of body, to the presence of a pelvic-fin and pelvic girdle, to the number of odontodes in the inter-opercular and opercular patches, to the number of dorsal and ventral procurrent rays. In addition, the analysis of mitochondrial DNA sequences identified a satisfactory genetic distance between this new species and its congeners. The new species from the Rio Ivaí reinforces its characteristics as an area of endemism for fishes in the Upper Rio Paraná basin.

A new miniature species of Characidium is described from the upper Rio Paraguay basin, Brazil. The new species can be diagnosed from all congeners by the presence of a dark-brown humeral blotch, vertically elongated (spanning 5 to 7 horizontal scale rows), with the shape of an upside-down acute triangle. Additionally, it can be diagnosed by a short lateral line (6 to 8 perforated scales), the absence of a conspicuous peduncular blotch, a lower number of principal caudal-fin rays (14-16) and by absence of the adipose fin. The new species is the smallest species of the genus; the largest specimen was 19.3 mm standard length.

This work aimed to describe Cambeva cauim, sp. nov., endemic to the Rio Iguacu basin, Brazil and redescribe Cambeva stawiarski using external and internal morphological data through the revision of specimens deposited in fish collections including the type material. In this process, we have also added comments on the possible type locality of C. stawiarski. Cambeva cauim, sp. nov. and C. stawiarski are mainly diagnosed by the anatomy and number of procurrent caudal-fin rays in addition to colouration and several meristic and morphometric characters. Both species are compared with other possibly related species and their synapomorphic characters are discussed. Cambeva cauim, sp. nov. and C. stawiarski along with other eight congeners are endemic to the Rio Iguacu basin, a high impacted freshwater region which could be considered as a biodiversity hotspot to the genus.

Characidium xavante was described from two tributaries of the Culuene River drainage, in the upper Xingu River basin. New samplings recorded the species for streams from the Kaaiapó River drainage (Teles Pires River drainage, upper Tapajós River basin) with additional specimens also recorded in the Xingu River basin, Paranatinga municipality, Mato Grosso State, Brazil. The new records represent an extension of the geographical distribution of the species, that from now on fits in a pattern of distribution known to be shared with other ca. 20 species of fishes. We suggest that Characidium xavante could be classified as Least Concern (LC), according to the International Union for Conservation of Nature Standards and Petitions Committee (IUCN).

Knowledge of the ichthyofauna of a hydrographic basin is the minimum necessary condition for the implementation of any measures for the exploration, management or preservation of water and fishing resources. Despite its relevance, the number of fish species across the Iguassu River basin is still uncertain. Thus, the objective of this study was to compile the fish species that occur in the extensive stretch of the basin above the Iguassu Falls. In addition, we recorded the level of threat of extinction for native species, the origin of nonnative species, and their main vectors of introduction. To achieve this goal, a survey was carried out through consultations with ichthyological collections as well as online databases. Also, a literature review was conducted using the search platforms Thomson Reuters, SciELO and Elsevier’s ScienceDirect to locate all articles published by March 2020 that addressed the topic “ichthyofauna in the Iguassu River basin”. The survey compiled a total of 133 fish species distributed in nine orders, 29 families and 72 genera. Seventy-nine fish species were recorded that occur throughout the entire length of the basin, 119 species that occur in the hydrographic units of the middle and lower Iguassu River (40 exclusive) and 93 species that occur in the hydrographic unit of the upper Iguassu River (14 exclusive). The endemism rate shown here for the Iguassu River basin (approximately 69%) contrasts with the 40 nonnative fish species recorded (approximately 30% of the total species in the basin). Successive impoundments, reductions in habitat quality and the increase in the number of nonnative species are the main threats to native species, especially to the endemic species; approximately 20% of these species were listed in some category of threat of extinction. We emphasize that constant monitoring of ichthyofauna is necessary to discover putatively undescribed species, as well as for the application of management strategies to mitigate the negative effects and promote the control of the spread of nonnative species. Resumo: Conhecer a ictiofauna de uma bacia hidrográfica compreende condição mínima necessária para que se possam implantar quaisquer medidas de exploração, manejo ou preservação dos recursos hídricos e pesqueiros. Apesar de sua relevância, o número de espécies de peixes de toda a bacia hidrográfica do rio Iguaçu ainda é incerto. Assim, o objetivo deste estudo foi compilar as espécies de peixes que ocorrem no extenso trecho da bacia acima das Cataratas do Iguaçu. Além disso, registramos o nível de ameaça de extinção às espécies nativas, a origem das espécies não nativas e suas principais vias de introdução. Para isso foi realizado um levantamento por meio de consultas a coleções ictiológicas, bem como aos bancos de dados online, além de revisão de literatura por meio do uso das plataformas de buscas Thomson Reuters, Scielo e Elsevier - ScienceDirect, que abordavam o tópico “ictiofauna da bacia do rio Iguaçu” e o período de tempo incluiu todos os trabalhos publicados até março de 2020. O levantamento compilou ao todo 133 espécies, distribuídas em nove ordens, 29 famílias e 72 gêneros. Em toda a extensão da bacia foram registradas 79 espécies de peixes. Nas unidades hidrográficas do médio e baixo rio Iguaçu foram registradas 119 espécies (40 exclusivas) e na unidade hidrográfica do alto rio Iguaçu foram registradas 93 espécies (14 exclusivas). A taxa de endemismo para a bacia do rio Iguaçu (aproximadamente 69%) contrasta com as 40 espécies de peixes não nativos registradas (aproximadamente 30% do total de espécies na bacia). Os sucessivos barramentos, a perda de qualidade de habitats e o aumento no número de espécies não nativas são ameaças às espécies autóctones, especialmente às endêmicas, as quais apresentam aproximadamente 20% listadas em alguma categoria de ameaça ao risco de extinção. Ressaltamos que o monitoramento constante da ictiofauna é necessário para a descoberta de espécies supostamente não descritas, bem como para a aplicação de estratégias de manejo para mitigar os efeitos negativos e promover o controle da disseminação de espécies não nativas.

The Cichlidae is one of the most diverse fish families in Neotropical and Afrotropical regions. It includes many species that are valued for aquaculture, the aquarium trade, and sport fishing, which has resulted in their introduction into different ecosystems worldwide. In the Americas, non-native cichlids have been recorded from southernmost Canada to northern Argentina, and North America has received the largest number of non-native cichlids followed by South and Central America. This group has a set of life history traits (e.g., parental care, multiple spawning, and piscivorous or omnivorous diets) that favors its occupation of new environments. This review provides information about non-native cichlids in the watersheds of the American continents including their distribution, predominant introduction vectors, reasons for success, and impacts on local ecosystems.

The encephalon gross morphology of Geophagus sveni is described, compared between male and female specimens and discussed in relation to evolutionary, ecological and behavioural aspects. The Student's t-test revealed that there are no sexual dimorphism regarding the volume or linear measurements obtained from the main encephalon subdivisions (telencephalon, tectum mesencephali, cerebellum, gustative lobes, hypothalamus and hypophysis) in proportion to encephalon length, which is congruent with the absence of external dimorphic characters and presence of biparental care behaviour. In all specimens examined, the tectum mesencephali is the largest structure of the encephalon, which may be explained by feeding habit and by the importance of the vision center in a social context (i.e., brood guarding and territory defence, which are common behaviours in cichlids). Also, the lobus vagi is more developed than usual for other teleosts, which may be explained by the presence, in G. sveni as well as in other Geophagini species, of a differentiated pharyngeal apparatus, probably an adaptation to winnowing, a specialized feeding habit. The little intraspecific variation in neuroanatomical characters observed herein indicates a possible source of morphological characters to be explored in cichlid phylogeny.

Turbidity plays an important role in aquatic predator-prey interactions. Increases in turbidity are expected to reduce prey capture rates, especially for visually oriented predators. However, there is also evidence indicating that turbidity may have little or no effect on predation rates. Here, we conducted a systematic review and meta-analysis of the relationship between turbidity and capture rate. We explored possible sources of heterogeneity in the effect sizes (capture strategy, predator's body size, relative eye size and turbidity range in the experiments) while controlling for the dependence among effects sizes and phylogenetic relationships among predator species. We found a consistent negative effect of turbidity on prey capture and that turbidity range (manipulated in the experiments) was the main factor accounting for between-study variation in effect sizes. Also, capture rates of both visually and non-visually oriented predators decreased with an increase in turbidity. In addition, for visually oriented fish predators, the relative eye size did not influence the effect sizes. Despite the paucity of studies for some groups of aquatic predators (mainly in tropical regions), we provide corroborative evidence that turbidity is a critical environmental factor controlling predator-prey interactions. This result is especially relevant considering that changes in turbidity is a human-induced pervasive environmental alteration resulted from, among other mechanisms, runoff after deforestation, eutrophication or oligotrophication in reservoir cascades, which imply changes in predator-prey interactions.

The rio das Cinzas and rio Itararé basins are important tributaries of the rio Paranapanema, a major left-bank tributary of the upper rio Paraná basin. The upper reaches of both drainages intersect the northern portion of the APA Escarpa Devoniana (Devonian Escarpment Environment Protection Area, EPA), an area considered crucial for the preservation of biodiversity. This study aimed to provide an ichthyofaunistic inventory for headwater streams of the rio das Cinzas and rio Itararé basins, both within and off of the borders of the EPA, increasing the knowledge about the species already known from streams in the rio Paranapanema system. We found 32 fish species, representing five orders and 12 families. Siluriformes was the richest order followed by Characiformes. Ten species presented high abundance of sampled individuals, contributing with 85.0% of all specimens. Most species were classified as occasional (captured in less than 25% of the samples) and only two species were classified as constant (captured in more than 50% of samples), which may reflect the altitudinal gradient. We did not record any introduced species in the sampled streams, reinforcing the need of, at least, maintaining the original area of the EPA. We expanded the geographic distribution of Astyanax bifasciatus to the upper rio Paraná system, confirming the cases of faunal exchange among several drainage systems in the limits of the Ponta Grossa Arch. Finally, we identified three putatively undescribed species that show a large biodiversity knowledge shortfall for the region studied. Resumo: As bacias do rio das Cinzas e do rio Itararé são afluentes importantes do rio Paranapanema, um dos principais afluentes da margem esquerda do alto rio Paraná. Os trechos superiores de ambas as drenagens interceptam a porção norte da Área de Proteção Ambiental (APA) da Escarpa Devoniana, uma área considerada crucial para a preservação da biodiversidade. Este trabalho teve como objetivo fornecer um inventário ictiofaunístico para riachos de cabeceira das bacias do rio das Cinzas e do rio Itararé, dentro e fora das fronteiras da APA, aumentando o conhecimento sobre as espécies já conhecidas dos riachos do rio Paranapanema. Encontramos 32 espécies de peixes, representando cinco ordens e 12 famílias. Siluriformes foi a ordem mais rica seguida por Characiformes. Dez espécies apresentaram alta abundância de indivíduos amostrados, contribuindo com 85,0% de todos os espécimes. A maioria das espécies foi classificada como ocasional (capturada em menos de 25% das amostras) e apenas duas espécies foram classificadas como constantes (capturadas em mais de 50% das amostras), o que pode refletir o gradiente altitudinal. Não registramos nenhuma espécie introduzida nos riachos amostrados, reforçando a necessidade de, pelo menos, manter a área original do APA. Expandimos a distribuição geográfica de Astyanax bifasciatus para o sistema do alto rio Paraná, confirmando os casos de intercâmbio faunístico entre vários sistemas de drenagem nos limites do Arco de Ponta Grossa. Finalmente, identificamos três espécies supostamente não descritas que mostram um grande déficit de conhecimento da biodiversidade para a região estudada.

The Madeira River is the most extensive tributary of the Amazon River and has the largest diversity of fishes in the world. On its right bank, the Madeira River receives the Jamari River, in which the first hydroelectric power plant (HPP) in State of Rondônia, Samuel HPP, was built. Besides this, other dams were built in the Jamari River and its tributaries, however, the available information in the scientific literature about the ichthyofaunistic diversity of this basin is rare. This work aims to provide an ichthyofaunistic inventory in a region of the Jamari river basin, in the State of Rondônia, where three small hydropower plants (SHPs) were implemented. The ichthyofauna was sampled in 16 expeditions between August 2015 and December 2018. Gill nets and seine nets were used with different meshes, as well as longlines and cast nets at different times of the day. Additionally, 81 INPA lots of species from the Samuel HPP area of influence were reanalyzed. Fish were identified according to the specialized literature, as well as in consultations with experts of various taxonomic groups. Voucher specimens of the species were cataloged and deposited in the ichthyological collection of the Núcleo de Pesquisas em Limnologia, Ictiologia e Aquicultura (Nupélia) of the Universidade Estadual de Maringá. A total of 230 species were recorded, of which 22 were putative new species, 117 were added to the Jamari River basin and 28 to the Madeira River basin. The continuation of the studies in this section of the Jamari river basin is fundamental for analysis of local impact due to the presence of dams. Moreover, the addition of putative new species to the Madeira River basin indicates gaps in the knowledge of Neotropical ichthyofauna.

The current analysis investigates whether the uplift of the Serra da Esperança and the Ponta Grossa Arch in the Serra Geral resulted in ichthyofaunistic changes in adjacent basins. For this, we describe the phylogeographic structure among populations of Trichomycterus collected in hydrographic basins in southern Brazil by using partial nucleotide sequences of the mitochondrial gene Cytochrome C Oxidase subunit I. Analyses revealed that the nomenclature Trichomycterus davisi fails to contain the whole genetic diversity range found in the collected specimens and indicates at least six genetic lineages in Trichomycterus. Diagnostic morphological characteristics not associated to T. davisi could be identified in some specimens from the Iguaçu Piquiri haplogroup, indicating the occurrence of species Trichomycterus stawiarski. The lack of morphological differences among the other clades clearly suggests a cryptic species case. Molecular analyses revealed at least five new species besides T. davisi in the hydrographic basins and support the interpretation that genetic structure in T. davisi species complex is explained by tectonic events intrinsic to the areas of influence of Serra da Esperança and the Ponta Grossa Arch which occurred around 1.7 My.

The use of multimetric indices (MMIs) became a common practice for evaluating ecological integrity of aquatic ecosystems. However, most developed MMIs ignore non-native species as an impact source to establish reference conditions. We developed an MMI to identify if non-native fish species are associated with Neotropical stream integrity by considering the presence of non-native species as an impact source. We calculated and evaluated responsiveness to the presence of non-native species using fish metrics, which were selected with a bootstrap procedure. Streams for calibration and validation were also selected with a bootstrap procedure. From the candidate MMIs generated, we selected models with different combinations of fish metrics. The generated MMIs presented a satisfactory performance in distinguishing reference streams from those impacted by non-native species. The abundance of non-native species was highly correlated with urbanization and seems to be more important than urbanization to drive native abundance loss. Our study is one of the first attempts to develop MMIs in which non-native species are considered as impact sources and used to identify impacted and reference sites. The final MMI that we developed might be a useful tool for aquatic biodiversity conservation and the development and application of non-native species control actions.

The invasion of tilapia can result in substantial impacts on native communities. Thus, understanding the spatial dynamics of invasions may help prevent future introductions and mitigate impacts. This study estimated the environmentally suitable areas for occurrence of eight tilapia species (genera Coptodon, Oreochromis, Pelmatolapia, and Sarotherodon) in the Americas and their invasive potential using Ecological Niche Models (ENMs). The United States is the most invaded country, receiving all tilapia species. In South America, the southeast and south regions of Brazil are highlighted as the areas where two species are concentrated. The ENMs predicted that all tilapia species have high invasive potential in the Americas, and despite having more tilapias in North America, South and Central Americas are more susceptible to tilapia invasion. All South American basins were predicted to harbor tilapia species that have not yet arrived on the subcontinent. Our study evidences the need to implement management measures and governmental policies in the Americas to deal with problems caused by tilapia introductions. In North America, the focus is on the control of tilapia populations and in Central and South America priority should be given to contention of introduction processes.

Knowledge on the hydrological evolution of the Neotropical region was used along with the current distribution of the anablepid species to investigate the historical biogeography of this family. Areas of endemism were delimited by endemicity analysis resulting in seven individual areas of endemism and three consensus areas located in northwestern Argentina, southern Brazil, and northern South America. These areas were discussed in the context of anablepid species diversification, especially for the genus Anableps and the subgenera Jenynsia and Plesiojenynsia. The existence of areas of endemism for the family analyzed reveals an intimate association with historical events that occurred in the geological evolution of South America, which can be associated with the main diversification patterns and historical hypotheses in the context of Neotropical freshwater fishes biogeography.

Astyanax gymnogenys Eigenmann was described from the middle rio Iguaçu basin, based on two specimens and A. longirhinus Garavello & Sampaio was described from the upper, middle and lower rio Iguaçu, based on several specimens. Due to their morphological similarity, including overlapping diagnostic characters between the two nominal species, allied to their occurrence in the same basin, doubts of their validity as independent taxa emerged. The validity of both taxa was analysed through the examination of type-material of both nominal species and additional material from the rio Iguaçu basin. The present study failed to support the recognition of A. longirhinus as a valid species and consequently, the latter species is herein considered a junior synonym of A. gymnogenys. The type-series of A. longirhinus was found to be composed of several Astyanax species. Astyanax gymnogenys can be differentiated from its congeners occurring at the rio Iguaçu basin by a combination of characters, including presence of vertically-elongated dark humeral blotch, margin of the third infraorbital distant from the margin of preopercle, leaving a broad naked area between these bones more than 25% of the depth of third infraorbital, body deepest at dorsal-fin origin or slightly ahead, and seven to 10 gill rakers on lower arch. We also examined all paratypes of A. scabripinnis paranae from the rio Iguaçu and conclude that they are not conspecific with the holotype, and consequently, that the species does not occur in the rio Iguaçu basin.

Satanoperca curupira, new species, is described from the rio Madeira basin in the State of Rondônia, Brazil. It is distinguished from all congeners by the following combination of characters: 3–7 dark-brown oblique stripes on the lachrymal (vs. 2 well-defined dark-brown stripes, or dark-brown stripes absent) and an irregular pattern of dark-brown stripes on cheek and opercular series (vs. cheek without dark-brown markings or with light-beige rounded spots). According to meristic and color pattern characters, the new species is considered a member of the S. jurupari species group, and is syntopic with S. jurupari, which is widespread in the Amazon basin. The restricted geographical range of the new species is congruent to that observed for some other Satanoperca species.

Knowledge of the fish species in river basins is among the minimum requirements for the management of water and fish resources. Therefore, the aim of this study was to update the fish species composition of the Piquiri River basin, upper Paraná River basin. Data were gathered from recent information published in specialized literature and records for ichthyology collections. This update reports the occurrence of 152 fish species distributed in 8 orders, 31 families, and 89 genera. Non-native species accounted for 20% of all species, and the construction of the Itaipu Power Plant and its fish ladder were the main vectors of introduction. Three percent of the species were endangered, and 11% were classified as migratory. The Piquiri River basin harbors a large number of species, some of which are rare, endangered, migratory, endemic, and even unknown by science. Because of this, maintaining the integrity of this river basin will support the persistence of regional biodiversity. Resumo: O conhecimento das espécies de peixes existentes em uma bacia hidrográfica é condição mínima necessária para a implantação de qualquer medida de manejo dos recursos hídricos e pesqueiros. Dessa forma, o objetivo deste estudo foi realizar uma atualização da composição das espécies de peixes da bacia do rio Piquiri, sistema do alto rio Paraná, proveniente de recentes informações contidas em estudos divulgados na literatura especializada e registros de espécies depositadas em coleções ictiológicas. A atualização do levantamento ictiofaunístico da bacia do rio Piquiri revelou a ocorrência de 152 espécies, as quais foram distribuídas em oito ordens, 31 famílias e 89 gêneros. Vinte por cento das espécies foram consideradas não nativas. O principal vetor de introdução foi a construção da barragem de Itaipu e seu sistema de transposição. Três por cento das espécies apresentaram alguma ameaça de extinção e 11% foram classificadas como migradoras. A bacia do rio Piquiri comporta grande número de espécies, algumas delas raras, ameaçadas de extinção, migradoras, endêmicas e até mesmo desconhecidas pela ciência. Dessa forma, a manutenção da integridade da bacia promoverá a persistência da biodiversidade regional.

Introduction: The Magellanic Penguin migrates on the ocean currents from its reproduction colonies in Patagonia to seek abundant food on the Brazilian continental shelf. The pineal gland, an endocrine gland, whose secretions are affected by the light-darkness photoperiod, has a basic function in the biological processes of migrating animals. Melatonin, the hormone synthesized and secreted by the pineal gland affects the circadian, circannual and seasonal cycle that directly affects the migration processes of land and sea birds. Materials and Methods: Specimens were collected on the southern coast of Brazil, morphometric assessments and histological analyses of the glands were undertaken. Results: The pineal gland of the Magellanic Penguin lies in a triangular space between the brain hemispheres and the cerebellum and close to the cavernous sinus that follow the region's dura mater. The average of the pineal gland of the penguins under analysis was 11.16mm and 1,69mm for length and thickness respectively. Test t and the coefficients of co-relationship (r) between the analyzed variables demonstrated that there was no co-relationship between the morphometric variables and the size of the pineal gland (p < 0.05). The Magellanic penguin's pineal gland has a club-like sacular shape with cells in threads, involved and interlaced by fibrous conjunctive tissues. Conclusion: Results corroborated data in the literature and showed that the pineal gland of these birds is relatively greater than that of other birds and its tissue composition is similar to that of other vertebrates.

Karyotypes and chromosomal characteristics of both minor and major rDNAs in four fish species known popularly as “lambaris”, namely Astyanax abramis (Jenyns, 1842), Astyanax asuncionensis Géry, 1972, Astyanax correntinus (Holmberg, 1891) and Astyanax sp. collected from downstream of the Iguassu Falls (Middle Paraná River basin), preservation area of the Iguassu National Park, were analyzed by conventional and molecular protocols. Astyanax abramis had diploid chromosome number 2n=50 (4m+30sm+8st+8a) and single AgNORs (pair 22), Astyanax asuncionensis had 2n=50 (8m+24sm+6st+12a) and single AgNORs (pair 20), Astyanax sp. had 2n=50 (4m+26sm+8st+12a) and single AgNORs (pair 25), and Astyanax correntinus had 2n=36 (12m+16sm+2st+6a) and multiple AgNORs (pairs 12, 15, 16, 17). FISH with 18S rDNA showed a single site for Astyanax abramis, Astyanax asuncionensis and Astyanax sp. and multiple for Astyanax correntinus (14 sites). FISH with 5S rDNA showed single 5S-bearing loci chromosome pair only for Astyanax asuncionensis and multiple for Astyanax abramis (four sites), Astyanax correntinus (five sites) and Astyanax sp. (four sites). Distinct distribution patterns of heterochromatin were observed for karyotypes of all species, with the exception of the first acrocentric chromosome pair characterized by centromeric, interstitial-proximal and telomeric blocks of heterochromatin on the long arm, which may represent homeology between karyotypes of Astyanax abramis and Astyanax asuncionensis. Our study showed species-specific characteristics which can serve in diagnosis and differentiation between Astyanax abramis and Astyanax asuncionensis, considered cryptic species, as well as strengthening the occurrence of a species of Astyanax not yet described taxonomically. In addition, the data obtained from first cytogenetic studies in Astyanax correntinus suggest a high similarity with Astyanax schubarti Britski, 1964, suggesting that these species may belong to the same morphological group and that can be phylogenetically related.

Summary This study reports the length-weight relationship estimatives (LWRs) for 55 fish species caught in the Iguatemi River drainage, Upper Parana River Basin, Mato Grosso do Sul State, Brazil. The LWRs of 15 of the species are provided for the first time.

We provide cytogenetic data for the threatened species Gymnogeophagus setequedas, and the first record of that species collected in the Iguaçu River, within the Iguaçu National Park’s area of environmental preservation, which is an unexpected occurrence for that species. We verified a diploid number of 2n = 48 chromosomes (4sm + 24st + 20a) and the presence of heterochromatin in centromeric and pericentromeric regions, which are conserved characters in the Geophagini. The multiple nucleolar organizer regions observed in G. setequedas are considered to be apomorphic characters in the Geophagini, whereas the simple 5S rDNA cistrons located interstitially on the long arm of subtelocentric chromosomes represent a plesiomorphic character. Because G. setequedas is a threatened species that occurs in lotic waters, we recommend the maintenance of undammed environments within its known area of distribution. RESUMO Fornecemos dados citogenéticos para a espécie ameaçada Gymnogeophagus setequedas, e o primeiro registro da espécie coletado no rio Iguaçu, na área de preservação ambiental do Parque Nacional do Iguaçu, a qual é uma área de ocorrência inesperada para esta espécie. Verificamos em G. setequedas 2n = 48 cromossomos (4sm + 24st + 20a) e heterocromatina presente nas regiões centroméricas e pericentroméricas, as quais indicam caracteres conservados em Geophagini. Múltiplas regiões organizadoras de nucléolos foram observadas em G. setequedas e são consideradas características apomórficas em Geophagini, enquanto cístrons de DNAr 5S simples e localizados intersticialmente no braço longo de cromossomos subtelocêntricos representam uma característica plesiomórfica. Visto que G. setequedas é uma espécie ameaçada de extinção que ocorre em águas lóticas, recomendamos a manutenção de ambientes livre de barragens em sua área de distribuição.

Recent sampling on fish from the headwaters of the Jordão and Areia rivers, combined with collection databases and specialized literature reports, yielded the first species inventory. Both basins reflect the high endemism rate associated with the Iguaçu River. However, four species previously thought to be restricted to the Jordão River basin are now known to also occur in the basin of the Areia River: Astyanax jordanensis Vera Alcaraz, Pavanelli & Bertaco, 2009; Characidiumtravassosi Melo, Buckup & Oyakawa, 2016; Jenynsia diphyes Lucinda, Ghedotti & Graça, 2006; and Trichomycterus igobi Wosiacki & de Pinna, 2008. This suggests an ancestral connection between the tributaries of the Jordão and Areia rivers, with putative drainage rearrangements resulting from the uplift of the Serra da Esperança. The endemic fauna of this region is presently threatened by invasive species, the construction of dams, and other human activities.

Australoheros is represented by species of Cichlidae spread over different Brazilian river systems. Individuals of Australoheros angiru were collected in isolated lagoons at 950 m of altitude in a dividing plateau between the basins of the Iguassu River and the Uruguay River, located in the Sao Lourenco do Oeste region (Santa Catarina State), and subject to basic and molecular cytogenetic analyzes. Moreover, a review about the occurrence and collections sites of A. angiru was used to the clarification of biogeographical issues of Australoheros and other species of fish that are common between the basins of the Uruguay River and Iguassu River. The analysis by conventional staining with Giemsa found a diploid number of 48 chromosomes (18 submetacentric + 30 subtelocentric/acrocentric) for males and females, without sex chromosome differentiation. The nucleolar organizing regions identified by silver impregnation and by fluorescence in situ hybridization with 18S rDNA probes showed to be simple, located on the end of the short arm of subtelocentric chromosome pair 15. Heterochromatin was observed in the centromeric region of most of the chromosomes of the complement, in addition to coincide with the nucleolar organizing regions. The data presented in this study are the first reports on the location of sites of 5S rDNA for Australoheros, being located in interstitial position on the long arm of subtelocentric chromosome pair 11. The basic and molecular cytogenetic data presented here contribute to the better understanding of chromosomal evolution of Cichlidae, act as interesting tools for taxonomy and phylogeny of the group, in addition to help in understanding the dispersion of A. angiru between the two hydrographic basins.