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Banded Knifefishes (Gymnotus, Gymnotidae) comprise the most species-rich, ecologically tolerant (eurytopic), and geo- graphically widespread genus of Neotropical electric fishes (Gymnotiformes), with 40 valid species occupying most hab- itats and regions throughout the humid Neotropics. Despite substantial alpha-taxonomic work in recent years, part...
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A new species of the bluntnose knifefish genus Brachyhypopomus Mago-Leccia is described from headwaters of upper Rio Juruena, and upper Rio Machado, Amazon basin, Brazil. The new species differs from all congeners by the absence of a small independent ossification of the Weberian complex located posterodorsally to the supraoccipital. It can be addi...
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... and Salminus hilarii valenciennes, 1850) or intraspecific territorial aggressions. However, the presence of two caudal filaments both with rays and originating from the vertebral column (vs just a report of a split tail; see ellis, 1913) was unknown to the Gymnotus carapo clade sensu Craig et al. (2018), a group of species that includes the species Gymnotus sylvius. the regeneration of caudal filament in gymnotiforms is well documented for several species (e.g., ellis, 1913;Meunier, 1981, 1988), including for those known only from fossil records Meunier and Gayet, 1991). in fact, regeneration in fishes is a condition showed to numerous other species (e.g., Meunier et al., 2010;Silva et al., 2015), and it is likely that it is a common pattern in Actinopterygii fishes. ...
Here we describe anomalies in two Neotropical freshwater fishes. Case 1 refers to a tumour above the left pectoral fin near the operculum of a specimen of Rhamdia quelen (Heptapteridae). Case 2 is a horizontal plane dichotomy of the caudal filament of an individual of Gymnotus cf. sylvius (Gymnotidae). We also provide a brief comment of the possible cause of the anomalies in individuals of both species.
... A través de los años, las colecciones que preserva la Fundación Azara han sido fundamentales para estudios filogenéticos, descripciones de especies nuevas para la ciencia, identificación de nuevos registros de especies no citadas previamente para el país, revisiones taxonómicas, estudios biogeográficos, estimaciones de la variación genética, estudios de especies invasoras, o simplemente como fuente de comparación anatómica para estudios paleontológicos, arqueológicos o biológicos, entre muchísimas otras investigaciones. Solo para citar algunos ejemplos, ilustramos a continuación una lista de artículos donde se describen o se mencionan especímenes biológicos conservados en la Fundación Azara: Teta et al., 2007;Chebez et al., 2008;Iwaszkiw et al., 2010;Torres y Jayat, 2010;Apesteguía et al., 2011;Bogan y Agnolin, 2011 a, b, c;Bogan y Di Martino, 2011;Otero et al., 2011;Conil y Nigro, 2012;Agnolin y Bogan, 2013;Bogan y Fernández, 2013;Cenizo y Tassara, 2013;Ercoli et al., 2013;Ferro, 2013;Martinelli y Bogan, 2013;Pine y Flores, 2013;Prevosti et al., 2013;Schiaffini et al., 2013;Agnolin et al., 2014;Bianchini y Arenas, 2014;Brancolini et al., 2014;Chimento et al., 2014;Tarnawski et al., 2014 a, b;Álvarez y Arnal, 2015;Bogan et al., 2015 a, b;Cardoso et al., 2015 a, b, c, d;Cardoso y Bogan, 2015;Crespo et al., 2015;D'Angelo et al., 2015;Jones et al., 2015;Patitucci et al., 2015;Piloni, 2015;Tarnawski et al., 2015;Alonso et al., 2016;Benítez et al., 2016;Giménez y Giannini, 2016;Cabrera et al., 2017;Guerrero et al., 2017;Junín, 2017;Segura et al., 2017;Terán et al., 2017;Teta y Campo, 2017;Agnolin et al., 2018;Briñoccoli et al., 2018;Cardoso et al., 2018;Chimento y Dondas, 2018;Craig et al., 2018;Díaz et al., 2018;Garcia-Marsà y Agnolin, 2018;Guerrero, 2018;Lucero et al., 2018;Rosso et al., 2018;Agnolin et al., 2019 a, b;Almiron et al., 2019;Álvarez y Flores, 2019;Bogan et al., 2019 a, b Acosta Hospitaleche, 2021; Vezzosi y Chimento, 2021;y Vezzosi et al., 2022. El manejo y cuidado de las colecciones de ciencias naturales está guiado por la preocupación por el futuro de los ejemplares que se conservan. ...
Las colecciones son un elemento distintivo en la historia de la práctica científica y la construcción de conocimiento. Son una fuente primaria de datos que conforman una herramienta indispensable como material de referencia y como reservorio fundamental para la validación y la trazabilidad de la investigación científica. El valor de las colecciones para la ciencia no radica solamente en la importancia intrínseca de los objetos, sino en que, muchas veces, la información vinculada con estos puede ser aún más importante que el objeto mismo.
La Fundación de Historia Natural Félix de Azara (Fundación Azara) resguarda un conjunto de aproximadamente 200.000 objetos de valor científico, provenientes de la Argentina y otras partes del mundo, correspondientes a las ciencias naturales y antropológicas. Este conjunto abarca desde plantas hasta meteoritos, pasando por fósiles, minerales, rocas, caracoles, insectos, peces, anfibios, reptiles, aves, mamíferos, máscaras, cerámicas, textiles y réplicas de esqueletos de dinosaurios y megamamíferos, por solo nombrar algunos ejemplos.
Este trabajo contextualiza, a través de una breve reseña sobre su historia, las colecciones científicas que conserva la Fundación Azara, que representan un patrimonio de incalculable valor científico, de uso público. Deseamos finalmente que permitan –mediante su estudio– a las actuales y futuras generaciones de investigadores, acrecentar el conocimiento sobre la naturaleza, sobre la historia de los seres vivos con los que habitamos la Tierra y sobre la historia humana.
... Although G. omarorum is mostly restricted to Uruguayan territory (Craig et al., 2018;Richer-de-Forges et al., 2009), it is found in sympatry with Gymnotus paraguensis ( part of the Gymnotus tigre clade within Gymnotus) in the provinces of Entre Rios and Corrientes, in the Argentinian Mesopotamia between the Parana and Uruguay rivers (Craig et al., 2018). The two species are morphologically similar, and while their signals largely overlap in their power spectral density, the temporal course differs in the late negative wave component that originates in the tail region (Rodríguez-Cattáneo and Caputi, 2009). ...
... Although G. omarorum is mostly restricted to Uruguayan territory (Craig et al., 2018;Richer-de-Forges et al., 2009), it is found in sympatry with Gymnotus paraguensis ( part of the Gymnotus tigre clade within Gymnotus) in the provinces of Entre Rios and Corrientes, in the Argentinian Mesopotamia between the Parana and Uruguay rivers (Craig et al., 2018). The two species are morphologically similar, and while their signals largely overlap in their power spectral density, the temporal course differs in the late negative wave component that originates in the tail region (Rodríguez-Cattáneo and Caputi, 2009). ...
Some fish communicate using pulsatile, stereotyped electric organ discharges (EODs) that exhibit species- and sex-specific time courses. To ensure reproductive success, they must be able to discriminate conspecifics from sympatric species in the muddy waters they inhabit. We have previously shown that they use the electric field lines as a tracking guide to approach conspecifics (electrotaxis) in both Gymnotus and Brachyhypopomus genera. Here we show that the social species Brachyhypopomus gauderio uses electrotaxis to arrive abreast a conspecific, coming from behind. Stimulus image analysis shows that, even in a uniform field, every single EOD causes an image in which the gradient and the local field time courses contain enough information to allow the fish to evaluate conspecific sex, and to find the path to reach it. Using a forced-choice test we show that sexually mature individuals orient themselves along a uniform field in the direction encoded by the time course characteristic of the opposite sex. This indicates that these fish use the stimulus image profile as a spatial guidance clue to find a mate. Embedding species, sex, and orientation cues is a particular example of how species can encode multiple messages in the same self-generated communication signal carrier, allowing for other signal parameters (e.g., EOD timing) to carry additional, often circumstantial, messages. This ‘multiple messages’ EOD embedding approach expressed in this species is likely to be a common and successful strategy widespread across evolutionary lineages and among varied signaling modalities.
... Only adult specimens were included in this analysis, that is, individuals with a total length (TL) of at least 150 mm. 17 Twelve morphometric variables were measured with a digital caliper that had a precision of 0.01 mm, 17,30 with minor adjustments. The matrix of morphometric data was dimensionalized using the principal component analysis (PCA), 54 run in the Vegan package of the R platform. ...
Gymnotus is the most studied genus of the order Gymnotiformes, but the morphological similarities of the different species make it difficult to identify taxa reliably. The present study is a continuation of the ongoing research into the taxonomic diversity of the stocks of Gymnotus sold as live bait in the Pantanal, Brazil. These studies have been based on cytogenetic analyses, DNA barcoding, and the analysis of coloration patterns. The results of the cytogenetic analysis confirmed the presence of three distinct strains, recognized as Gymnotus paraguensis, G. sylvius, and G. pantanal. However, the results revealed that the molecular operational taxonomic units identified as G. paraguensis actually include a relatively diverse set of fish, separated by considerable genetic distances. As the G. paraguensis specimens also presented considerable variation in coloration patterns, further genetic diversity analyses were conducted on these individuals, to test the hypothesis that more than one species is present in this cytotaxonomic unit. The haplotype network revealed a regional pattern in the distribution of this species. The results indicate that the observed variation in coloration patterns is associated with a high degree of phenotypic plasticity in G. paraguensis. These findings emphasize the importance of using an integrative approach for a more accurate diagnosis of Gymnotus, in particular, the species marketed as live bait for the fisheries of the upper Paraguay River basin in the Brazilian Pantanal.
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... The collecting sites of O. piribebuy are relatively distant from each other (Fig. 1). However, a similar distribution pattern, with a large gap between collecting sites in the rio Paraguay basin, was already described for two non-loricariid species -Tatia neivai (Ihering, 1930) and Gymnotus pantanal Fernandes, Albert, Daniel-Silva, Lopes, Crampton & Almeida-Toledo, 2005 (Sarmento-Soares & Martins-Pinheiro, 2008;Craig et al., 2018). ...
Cascudinhos are a group of small benthic fishes included in the Hypoptopomatinae subfamily, inhabiting small to moderate streams and rivers within the Neotropical region, from Venezuela to Northern Argentina. Until now, Otothyropsis piribebuy originally described from the rio Paraguay basin, in Paraguay, is the only species of the genus not recorded in Brazil. Recent samples in the rio Tererê, rio Paraguay basin, Brazil, revealed a population of Otothyropsis with uncertain taxonomic identity. Therefore, the study aimed to unveil the distribution of Otothyropsis within Brazilian territory. External morphology, osteology, measurements, and counts (plates, teeth, and rays) of these specimens from rio Tererê were compared to data from the original description of O. piribebuy, and also with specimens of O. piribebuy sampled in Paraguayan territory. Observations indicated no differences among the analyzed specimens. Furthermore, a Principal Component Analysis (PCA), carried out using log-transformed measures from Brazilian and Paraguayan specimens, showed no separation of these populations, also indicating that all analyzed specimens pertain to the same species. Based on this, a prediction map of distribution, using Maximum Entropy, was produced. The correct identification of spatial range of occurrence is an essential step to ensure the conservation of species, and the extended distribution of Otothyropsis piribebuy was confirmed, enhancing the list of neotropical fish from Brazil.
... cylindricus LaMonte, at 15˚N) to the Rio Salado in Argentina (G. carapo australis Craig et al.,at 35˚S) [2] (Table 2). Gymnotus species exhibit a variety of phenotypes, ranging from meter-long floodplain piscivores (e.g. ...
The diversity of gymnotid electric fishes has been intensely studied over the past 25 years, with 35 species named since 1994, compared to 11 species in the previous 236 years. Substantial effort has also been applied in recent years to documenting gymnotid interrelationships , with seven systematic studies published using morphological and molecular datasets. Nevertheless, until now, all gymnotids have been assigned to one of just two supraspecific taxa, the subfamily Electrophorinae with one genus Electrophorus and three valid species and the subfamily Gymnotine also with one genus Gymnotus and 43 valid species. This simple classification has obscured the substantial phenotypic and lineage diversity within the subfamily Gymnotine and hampered ecological and evolutionary studies of gymnotid biology. Here we present the most well-resolved and taxon-complete phylogeny of the Gymnotidae to date, including materials from all but one of the valid species. This phy-logeny was constructed using a five-gene molecular dataset and a 115-character morphological dataset, enabling the inclusion of several species for which molecular data are still lacking. This phylogeny was time-calibrated using biogeographical priors in the absence of a fossil record. The tree topology is similar to those of previous studies, recovering all the major clades previously recognized with informal names. We propose a new gymnotid classification including two subfamilies (Electrophorinae and Gymnotinae) and six subgenera within the genus Gymnotus. Each subgenus exhibits a distinctive biogeographic distribution, within which most species have allopatric distributions and the subgenera are diverged from one another by an estimated 5-35 million years. We further provide robust taxonomic diagnoses , descriptions and identification keys to all gymnotid subgenera and all but four species. This new taxonomy more equitably partitions species diversity among supra-specific taxa, employing the previously vacant subgenus and subfamily ranks. This new taxonomy renders known gymnotid diversity more accessible to study by highlighting the deep divergences (chronological, geographical, genetic and morphological) among its several clades.
... The identification of species in this genus based on morphological characters is sometimes challenging due to the morphological conservatism among species 2 e190075 [2] and high phenotypic plasticity within species. Many efforts have been made based on studies of morphology, cytogenetics, molecular, and electrical signals to elucidate the taxonomy of electric fishes, including Gymnotus (Alves-Gomes et al., 1995;Albert, Crampton, 2003;Fernandes et al., 2005;Margarido et al., 2007;Maxime, Albert, 2009;Scacchetti et al., 2011;Milhomem et al., 2012;Tagliacollo et al., 2016;Sousa et al., 2017;Craig et al., 2017Craig et al., , 2018. ...
... Species of Gymnotus known to occur in the Upper Paraná basin include: G. carapo australis Craig, Crampton & Albert, 2017, G. cuia, G. inaequilabiatus, G. pantanal, G. pantherinus, G. paraguensis Albert & Crampton, 2003 and G. sylvius (Craig et al., 2017;Craig et al., 2018). Of these species, G. carapo australis, G. cuia, and G. pantanal are ecologically abundant and G. inaequilabiatus, G. pantherinus, G. paraguensis and G. sylvius are not abundant. ...
... cuia presented also 99% of identity with Gymnotus new sp. RS2 that, according to Tagliacollo et al. (2016), belongs to G. carapo clade and not to G. tigre clade, which includes the species G. inaequilabiatus and G. paraguensis (Maxime, Albert, 2014;Craig et al., 2018). It is possible that the specimens identified as G. inaequilabiatus in previous studies based on Graça, Pavanelli (2007) and Ota et al. (2018) may be actually G. cuia. ...
The capture of live bait for sport fishing is an important activity for fishing communities. The main species used for this purpose are members of the genus Gymnotus, which comprises numerous species of cryptic nature that are difficult to identify based on external morphology. The aims of this work were to identify through partial sequences of the COI gene Gymnotus species fished in the Jacaré-Guaçu River, SP, and to develop a molecular diagnostic approach using PCR-RFLP to identify these species. Partial COI sequences were compared to those of other species deposited in GenBank. The sequences were assessed in the NEBCutter program to determine restriction sites in the sequence and the enzymes to be tested. Phenetic analysis performed by Neighbor-Joining method showed that the specimens sampled belong to two species preliminary identified here as G. cf. sylvius and G. cf. cuia, with G. cf. sylvius accounting for 95.2% of the individuals sampled. The enzymes NlaIII and SacI generated fragments that allowed distinguishing the Gymnotus species using PCR-RFLP. This analysis can be used to accurately identify these species, which is fundamental for monitoring Gymnotus fishing and assessing the conservation of this genetic resource.
... Gymnotus carapo australis Craig, Crampton & Albert, 2017 (Fig. 7e) Distinguished from conspecifics by possessing 25 obliquely-oriented dark brown bands with wavy margins and about three times as broad the paler interbands, slender body (73 % of HL), slender head (58 % of HL) and longer head (11 % of TL). The species is found throughout South America east of the Andes, with the subspecies restricted to the La Plata basin (Craig et al. 2017(Craig et al. , 2018. A nocturnal ambush predator, the only specimen was collected in the vegetated areas along the lake edge, typical of their preferred swampy and headwater habitats (Albert 2001;Craig et al. 2018). ...
... The species is found throughout South America east of the Andes, with the subspecies restricted to the La Plata basin (Craig et al. 2017(Craig et al. , 2018. A nocturnal ambush predator, the only specimen was collected in the vegetated areas along the lake edge, typical of their preferred swampy and headwater habitats (Albert 2001;Craig et al. 2018). ...
Despite the high fish diversity of the Paraguay basin, there is still large uncertainty about the presence and distribution of species in the country of Paraguay. Here, I present an annotated checklist to the fish of Paraguay's only true lake, Laguna Blanca, in San Pedro department, based on samples collected opportunistically between 2012 and 2017. A total of 32 species from 16 families and 6 orders were found, although the actual total is estimated at between 36 and 58 species. This included an unnamed species of Hemigrammus and the first country record of Moenkhausia bonita. Live colouration is also described for Hemigrammus mahnerti. One species was endemic to Paraguay, four to the Paraguay river basin, eight to the Paraná-Paraguay and 15 to the Rio De La Plata, whilst two were potamodromous. Species composition is typical of Neotropical lentic systems but with a distinct scarcity of benthivores, likely associated with the oligotrophic conditions of the lake. The threats to this unique ecosystem, through uncontrolled development, illegal deforestation, pollution and overfishing are imminent and recommendations for its protection are given.
... Ellis' perception of G. carapo was influential, and a number of subsequent authors in the 20 th century shared his view about the identity of that species (e.g., Eigenmann and Allen, 1942;Fowler, 1951;Ringuelet et al., 1967;Berra, 2007). More than a hundred years has passed since that seminal study, and Gymnotus is currently considered the most species-rich genus in Gymnotiformes, with more than 40 valid species (e.g., Ferraris et al., 2017;Craig et al., 2018aCraig et al., , 2018b. Many of those were described after a review of G. carapo (Albert and Crampton, 2003), also including a recent proposal of a subspecific taxonomic arrangement regarding that species (Craig et al., 2017). ...
... carapo'' or ''Gymnotus sp.,'' have been made available in recent studies mainly dealing with ecological and environmental issues (e.g., Rosa and Groth, 2004;Silva Filho et al., 2011;El-Deir et al., 2012;GEOSISTEMAS, 2012;Collier et al., 2015). Collections by one of us (CDS) at the Refúgio Ecológico Charles Darwin (RECD), a protected area north of Recife (rio Botafogo drainge, Igarassu municipality), as well as the detailed study of additional material available at the Museu Nacional (Rio de Janeiro)-MNRJ (Rio de Janeiro, Brazil) Craig et al., 2018b), which is described herein. ...
... Tagliacollo et al. (2016) recognized the ''Gymnotus carapo clade'' (their ''Node 196'') based on two synapomorphies, ''anal fin membrane with pale posterior patch'' and ''teeth with triangular, arrow-head shape,'' both also noted in Gymnotus darwini. More recently, Craig et al. (2018b) noted that members of the ''G. carapo clade'' were distinguished from congeners (except those in the ''G. ...
A new species of Gymnotus is described from coastal river systems in the Pernambuco State, Brazil. It is phylogenetically referred to the “Gymnotus carapo group clade” for presenting a clear patch posteriorly at anal fin, two independent pores at dorsoposterior corner of preopercle, a single row of well-developed teeth (most arrowhead-shaped) anteriorly on premaxilla, cleithrum with anterior notch, and by the relative anus to anal-fin distance, pectoral-fin length, and maxilla length. The new species is distinguished from all congeners in the “Gymnotus carapo group clade” by a unique set of characters of uncertain polarity, including the number of dark bands along the body, dark bands along body three to four times wider than pale interbands, with nearly straight margins (never broken anteriorly into irregular dark spots), and bands nearly uniform in color, number of scales above lateral line, number of lateral-line perforated scales to first ventral ramus, number of total pored lateral-line scales, head length, snout length, body depth, number of anal-fin rays, number of pectoral-fin rays, number of precaudal vertebrae, number of teeth on anterior row of premaxilla, and number of teeth along outer row of dentary. The new taxon represents the first species of Gymnotus described from localities in northeastern Brazil, north of the mouth of the rio São Francisco.
... This problem has already been highlighted by Albert and Crampton (2003). Furthermore, data on G. carapo has recently been reviewed and new species and subspecies have been delimitated (Craig et al., 2017(Craig et al., , 2018. ...
... However, these specimens are probably not G. inaequilabiatus. Although some authors have assigned G. inaequilabiatus to the carapo clade (Albert et al., 2004;Lovejoy et al., 2010), recent morphological studies have suggested that this species belongs to the tigre clade, together with G. paraguensis (Craig et al., 2018). On the basis of DNA sequences obtained from the GenBank, G. ...
... Moreover, considering the geographical distribution of the specimens of Gymnotus sp. belonging to the carapo complex, some may correspond to new species or subspecies already described by Craig et al. (2017Craig et al. ( , 2018. ...
Gymnotus is the most species rich genus of electric fish in the Neotropical region. Recently, a previously unknown diversity has been found in this genus, motivating a pursuit for new species. In this study, a fragment of the mitochondrial Cytochrome c Oxidase subunit I (COI) gene was used to analyse the diversity of 10 morphospecies of Gymnotus (G. carapo, G. pantanal, G. sylvius, G. ineaquilabiatus, G. pantherinus, G. coropinae, G. jonasi, G. cylindricus, G. chaviro, G. tigre) in two Neotropical river basins (Paraná River and Doce River), in addition to specimens identified as Gymnotus sp.. At least 15 OTUs were determined, eight of which belonged to the carapo complex. Our results indicate the existence of at least four Gymnotus species belonging to the carapo clade in the upper Paraná River basin and possibly erroneous previous identifications. Besides that, we identified a possible new species of Gymnotus in the Rio Doce basin. The Generalized Mixed Yule Coalescent (GMYC) and Poisson Tree Processes (PTP) molecular delimitation approaches place other specimens found in the upper Paraná River and Guaíba River (Gymnotus sp.) in well‐established groups that should be considered in studies involving the carapo complex.
