Marine catfishes (Ariidae-Siluriformes) from the Coastal Amazon: mitochondrial DNA barcode for a recent diversification group?

Background: Ariidae species play a significant role as fishing resources in the Amazon region. However, the family's systematic classification is notably challenging, particularly regarding species delimitation within certain genera. This difficulty arises from pronounced morphological similarities among species, posing obstacles to accurate species recognition. Methods: Following morphological identification, mitochondrial markers (COI and Cytb) were employed to assess the diversity of Ariidae species in the Amazon. Results: Our sampling efforts yielded 12 species, representing 92% of the coastal Amazon region's diversity. Morphological identification findings were largely corroborated by molecular data, particularly for species within the Sciades and Bagre genera. Nonetheless, despite morphological support, Cathorops agassizii and Cathorops spixii displayed minimal genetic divergence (0.010). Similarly, Notarius quadriscutis and Notarius phrygiatus formed a single clade with no genetic divergence, indicating mitochondrial introgression. For the majority of taxa examined, both COI and Cytb demonstrated efficacy as DNA barcodes, with Cytb exhibiting greater polymorphism and resolution. Consequently, the molecular tools utilized proved highly effective for species discrimination and identification.

Diet of three juvenile fish species of the coastal zone of a Southwest Atlantic beach, Brazil

Surf zones are associated with a shelter area, nursery and feeding for several species of fish. In this study, the dietary habits of three species of fish with demersal habits (Gulf kingcroakerMenticirrhu gracilis, Whitesea catfishGenidens barbusand Barbu Polydacytlus virginicus), were verified in the surf zone area of an active urban beach of Baixada Santista, concerning structure in size, day and night abundances and overlapping diets. Atotal of 617 fish were analyzed, of which 362 were 194 were G. barbusand 61 were P. virginicus. Stomach contents, represented in Relative Importance Index diagrams, showed that the bivalve Donax gemmulais the most important food item for M. gracilis, scales of Teleostei for G. barbusand Euphausiacea for P. virginicus. In order to evaluate the similarity of the diets, the Macarthur & Levins indices and a cluster analysis with the Bray-Curtis distance were applied revealing that the diet is 44% different between G. barbusand M. gracilis, 5% between G. barbusand P. virginicusand of 84% between M. gracilisand P. virginicus. Anthropogenic waste like plastic, nylon, metal pieces, were only occasionaly observed.(AU)

Morphological and molecular (28S rRNA) data of monogeneans (Platyhelminthes) infecting the gill lamellae of marine fishes in the Campeche Bank, southwest Gulf of Mexico.

During the examination of 913 fish specimens belonging to four families in the Campeche Bank (Gulf of Mexico), 23 gill ectoparasitic monogenean species were found, which belong to three families: Dactylogyridae, Microcotylidae and Diclidophoridae. The species Euryhaliotremaamydrum, E.carbuncularium, E.dunlapae, E.fajeravilae, E.fastigatum, E.longibaculum, E.paracanthi, E.tubocirrus, Haliotrematoidescornigerum, H.gracilihamus, H.heteracantha, H.longihamus, H.magnigastrohamus, H.striatohamus, Hamatopedunculariabagre, Neotetraonchusbravohollisae, and N.felis (all Dactylogyridae) were found on the hosts Lutjanussynagris, L.griseus, Ariopsisfelis, Bagremarinus, Archosargusrhomboidalis, and Haemulonplumieri. Additionally, Microcotylearchosargi, Microcotyle sp., and Microcotyloidesincisa (all Microcotylidae) were found on L.griseus and A.rhomboidalis; finally, Choricotyle sp. 1, Choricotyle sp. 2, and Choricotyle sp. 3 (all Diclidophoridae) were found on H.plumieri. The prevalence, abundance, mean intensity of infection, and supplementary taxonomic revisions for all monogeneans found are provided. Partial sequences of the 28S rRNA gene were also obtained for monogeneans of ariid, sparid, and haemulid host fishes to explore their systematic position within the Monogenea. New locality and host records for some previously described species of Euryhaliotrema, Hamatopeduncularia, Microcotyle, and Choricotyle from lutjanid, ariid, sparid, and haemulid hosts were reported. The present study adds evidence supporting the interoceanic occurrence of the same monogenean species (on lutjanids) on the west-east Atlantic and Pacific Oceans (= amphiamerican species). As previously suggested, there are at least, two possibilities to explain that parasite distribution: differentiation of morphological features in these monogeneans have resulted in only slight to insignificant morphological changes developing over the extended period of 3.2 mya (when the Isthmus of Panama was closing) and/or speciation is only evident at molecular level.

Isotopic niche of the catfishes Bagre bagre and Genidens barbus in a coastal area of south-eastern Brazil / Nicho isotópico dos bagres Bagre bagre e Genidens barbus em área costeira do sudeste do Brasil

Abstract: The isotopic niche of Bagre bagre and Genidens barbus target of commercial fisheries in a marine coastal area from northern Rio de Janeiro State (~21ºS), south-eastern Brazil was compared to evaluate the feeding assimilation and the trophic relationship. The mean isotopic values of the catfishes and their food items in the δ13C-δ15N space were coherent with their respective trophic positions. The relative contributions of the food items highlighted the shrimp Xiphopenaeus kroyeri as the most assimilated item in the diet of B. bagre, while for G. barbus the model highlighted the fish Porichthys porosissimus. The absence of niche overlap together with the trophic evenness point to a reduced feeding overlap between B. bagre and G. barbus in northern Rio de Janeiro State.

Resumo: O nicho isotópico de Bagre bagre e Genidens barbus alvos de pescarias comerciais em uma área costeira marinha do norte do estado do Rio de Janeiro (~21ºS), sudeste do Brasil, foi comparado para avaliar a assimilação alimentar e a relação trófica. Os valores isotópicos médios dos bagres e de seus itens alimentares em δ13C-δ15N foram coerentes com suas respectivas posições tróficas. As contribuições relativas dos itens alimentares destacaram o camarão Xiphopenaeus kroyeri como o item mais assimilado na dieta de B. bagre, enquanto para G. barbus o modelo destacou o peixe Porichthys porosissimus. A ausência de sobreposição de nicho juntamente com a uniformidade trófica aponta para uma sobreposição alimentar reduzida entre B. bagre e G. barbus no norte do estado do Rio de Janeiro.

Hábito alimentar do bagre sciades herzbergii (Siluriformes, Ariidae) da ilha dos caranguejos, Maranhão, Brasil / Feeding habits of the catfish sciades herzbergii (Siluriformes, Ariidae) in caranguejos island, Maranhão, Brazil

The article describes the feeding habits of the catfish Sciades herzbergii caught in the Crabs Island (Ilha dos Caranguejos), an important coastal area of the Maranhão state, Brazil. A total of 167 individuals were collected: 110 females and 57 males. All the stomach contents were identified to the closest taxonomic level. The frequency of occurrence, biomass, numerical frequency and index of relative importance (IRI) of food items were determined for both genders. Stomach repletion was predominant, demonstrating good feeding conditions for S. herzbergii. The main alimentary items in the diet of this catfish were crustaceans, fish, oligochaets and polychaets, and the decapods crustaceans were the most representative.

Hábito alimentar do bagre Sciades herzbergii (Siluriformes, Ariidae) da Ilha dos Caranguejos, Maranhão, Brasil / Feeding habits of the catfish Sciades herzbergii (Siluriformes, Ariidae) in Caranguejos Island, Maranhão, Brazil

The article describes the feeding habits of the catfish Sciades herzbergii caught in the Crabs Island (Ilha dos Caranguejos), an important coastal area of the Maranhão state, Brazil. A total of 167 individuals were collected: 110 females and 57 males. All the stomach contents were identified to the closest taxonomic level. The frequency of occurrence, biomass, numerical frequency and index of relative importance (IRI) of food items were determined for both genders. Stomach repletion was predominant, demonstrating good feeding conditions for S. herzbergii. The main alimentary items in the diet of this catfish were crustaceans, fish, oligochaets and polychaets, and the decapods crustaceans were the most representative.(AU)

Plasma ion levels of freshwater and marine/estuarine teleosts from Southern Brazil

The purpose of this study was to investigate Na+, Cl-, K+, Ca2+, and Mg2+ levels in the plasma of freshwater and marine/estuarine teleosts collected at different salinities (0 to 34) from the estuarine and freshwater portions of the São Gonçalo channel in Southern Brazil. Any relationship between plasma ion levels and salinity and the capacity of ionic regulation of teleosts found at three or more different salinities (Genidens barbus and Micropogonias furnieri) was also investigated. Results showed no relationship between plasma ion levels and salinity when considering all species together, but the two species collected from three or more different salinities showed a significant positive relationship between plasma ion levels and salinity, indicating that G. barbus and M. furnieri have a high capacity to regulate plasma ion levels at both low and high salinities.

A proposta deste estudo foi investigar os níveis de Na+, Cl-, K+, Ca2+, and Mg2+ no plasma de teleósteos de água doce e marinhos/estuarinos coletados em diferentes salinidades (0 a 34) nas porções de água doce e estuarinas do Canal São Gonçalo, sul do Brasil. Uma possível relação entre os níveis iônicos plasmáticos e a salinidade também foi investigada bem como a capacidade de regulação iônica dos teleósteos coletados em três ou mais salinidades (Genidens barbus e Micropogonias furnieri). Os resultados mostraram que não houve relação entre os níveis iônicos no plasma com a salinidade quando considerando todas as espécies juntas, mas as duas espécies coletadas em três ou mais salinidades mostraram uma relação significativamente positiva entre níveis iônicos no plasma e salinidade, mostrando que G. barbus e M. furnieri apresentaram uma grande capacidade para regular os íons do plasma em baixas e altas salinidades.

Descripción de una nueva especie de bagre marino fósil (Teleostei, Siluriformes, Ariidae) del Mioceno de la provincia de Río Negro, Argentina

En este trabajo se describen dos cráneos de la familia Ariidae procedentes del miembro Saladar de la Formación Gran Bajo del Gualicho, ubicados en las Salinas del Gualicho, provincia de Río Negro, Argentina. La edad de los depósitos del Miembro Saladar se remonta al Mioceno Temprano alto/Mioceno Medio bajo. Los materiales son asignados a una nueva especie extinta del género viviente Genidens. Este nuevo taxón se distingue de todas las especies actuales por presentar un proceso supraoccipital muy corto, ancho y redondeado, extraescapular subcircular y mesetmoides amplios con una conspicua escotadura mesial, frontales prácticamente planos en vista lateral y margen lateral de los huesos esfenóticos rectilíneo. Genidens sp. nov., representa el registro más antiguo para el género y constituiría una especie de aspecto similar a las formas actuales del género. sp. nov., representa el registro más antiguo para el género y constituiría una especie de aspecto similar a las formas actuales del género.

Two fossil crania referable to the siluriform fish family Ariidae are described. The specimens come from the Early Late Miocene-Lower Middle Miocene Saladar Member of the Gran Bajo del Gualicho Formation, located at Salinas del Gualicho, Río Negro province, Argentina. The materials are referred to a new species of the recent genus Genidens. The new taxon is distinguished from remaining living species in having a very short, broadened and rounded supraoccipital process, subrounded extrascapular and wide mesethmoid with a median notch, flat frontals, and straight lateral margins of the sphenotics. Genidens ancestralis sp. nov. represents the oldest (and only known) fossil record for the genus, and constitutes a relatively small-sized species, very similar in general traits to living forms of Genidens.

Plasma ion levels of freshwater and marine/estuarine teleosts from Southern Brazil

The purpose of this study was to investigate Na+, Cl-, K+, Ca2+, and Mg2+ levels in the plasma of freshwater and marine/estuarine teleosts collected at different salinities (0 to 34) from the estuarine and freshwater portions of the São Gonçalo channel in Southern Brazil. Any relationship between plasma ion levels and salinity and the capacity of ionic regulation of teleosts found at three or more different salinities (Genidens barbus and Micropogonias furnieri) was also investigated. Results showed no relationship between plasma ion levels and salinity when considering all species together, but the two species collected from three or more different salinities showed a significant positive relationship between plasma ion levels and salinity, indicating that G. barbus and M. furnieri have a high capacity to regulate plasma ion levels at both low and high salinities.(AU)

A proposta deste estudo foi investigar os níveis de Na+, Cl-, K+, Ca2+, and Mg2+ no plasma de teleósteos de água doce e marinhos/estuarinos coletados em diferentes salinidades (0 a 34) nas porções de água doce e estuarinas do Canal São Gonçalo, sul do Brasil. Uma possível relação entre os níveis iônicos plasmáticos e a salinidade também foi investigada bem como a capacidade de regulação iônica dos teleósteos coletados em três ou mais salinidades (Genidens barbus e Micropogonias furnieri). Os resultados mostraram que não houve relação entre os níveis iônicos no plasma com a salinidade quando considerando todas as espécies juntas, mas as duas espécies coletadas em três ou mais salinidades mostraram uma relação significativamente positiva entre níveis iônicos no plasma e salinidade, mostrando que G. barbus e M. furnieri apresentaram uma grande capacidade para regular os íons do plasma em baixas e altas salinidades.(AU)

Descripción de una nueva especie de bagre marino fósil (Teleostei, Siluriformes, Ariidae) del Mioceno de la provincia de Río Negro, Argentina

En este trabajo se describen dos cráneos de la familia Ariidae procedentes del miembro Saladar de la Formación Gran Bajo del Gualicho, ubicados en las Salinas del Gualicho, provincia de Río Negro, Argentina. La edad de los depósitos del Miembro Saladar se remonta al Mioceno Temprano alto/Mioceno Medio bajo. Los materiales son asignados a una nueva especie extinta del género viviente Genidens. Este nuevo taxón se distingue de todas las especies actuales por presentar un proceso supraoccipital muy corto, ancho y redondeado, extraescapular subcircular y mesetmoides amplios con una conspicua escotadura mesial, frontales prácticamente planos en vista lateral y margen lateral de los huesos esfenóticos rectilíneo. Genidens sp. nov., representa el registro más antiguo para el género y constituiría una especie de aspecto similar a las formas actuales del género. sp. nov., representa el registro más antiguo para el género y constituiría una especie de aspecto similar a las formas actuales del género.

Two fossil crania referable to the siluriform fish family Ariidae are described. The specimens come from the Early Late Miocene-Lower Middle Miocene Saladar Member of the Gran Bajo del Gualicho Formation, located at Salinas del Gualicho, Río Negro province, Argentina. The materials are referred to a new species of the recent genus Genidens. The new taxon is distinguished from remaining living species in having a very short, broadened and rounded supraoccipital process, subrounded extrascapular and wide mesethmoid with a median notch, flat frontals, and straight lateral margins of the sphenotics. Genidens ancestralis sp. nov. represents the oldest (and only known) fossil record for the genus, and constitutes a relatively small-sized species, very similar in general traits to living forms of Genidens.

Taxocenose de bagres marinhos (Siluriformes, Ariidae) da região estuarina de São Vicente, SP, Brasil / Taxocenose of marine catfish (Siluriformes, Ariidae) in the complex bay-estuary of São Vicente, SP, Brazil

O objetivo do trabalho foi analisar a taxocenose de bagres marinhos do complexo baía-estuário de São Vicente, SP. As coletas foram mensais, no período de setembro de 2000 a agosto de 2002, em quatro regiões do estuário. Foram capturados 3.985 exemplares, pertencentes a cinco gêneros e seis espécies, totalizando 47.807 g. A espécie Cathorops spixii apresentou a maior abundância numérica com 1.569 indivíduos amostrados. No transecto I (próximo da região costeira) foi registrada a maior riqueza e no transecto IV (estuário acima) a maior abundância com 2.602 exemplares e peso de 26.236 g. Em março de 2002 registrou-se a maior abundância com 687 indivíduos e o maior peso ocorreu em fevereiro de 2002 (8.816 g). A salinidade da água de fundo, ao longo do período de estudo, variou entre 14 e 36 e a temperatura da água variou entre 19 e 30 ºC. Na região amostrada foram capturados exemplares jovens e adultos, ocorrendo um predomínio de jovens, o que demonstra que esta área apresenta condições favoráveis para crescimento.

The purpose of this study was to analyze the taxocenose of marine catfish in the complex bay-estuary of Sao Vicente, Brazil. The sampling was done monthly from September/2000 to August/2002, in four places of the estuary. Were caught 3.985 individuals belonging for 5 genus and 6 species, totalizing 47.807 g. The specie Cathorops spixii showed the biggest plentiful with 1.569 individuals sampled. In the transect I (close to the coastal region), it was registered the biggest richness (6 species) and in the transect IV (upper estuary) the biggest number of individuals (n = 2.602) e weight of 26.236 g. In March/2002 were registered the biggest occurrence with 687 individuals and biggest weight in February/2002 (8.816 g). The bottom water salinity, in the time of study, changed between 14 and 36, and the water temperature varied between 19 and 30 ºC. In the sample place juveniles and adults' individuals were caught, a mostly juvenile which demonstrates that of this place shows favorable conditions for growth.

Ontogenetic and seasonal shifts in the diet of the pemecou sea catfish Sciades herzbergii (Siluriformes: Ariidae), from a macrotidal mangrove creek in the Curuçá estuary, Northern Brazil

The feeding ecology of pemecou sea catfish (Sciades herzbergii) was studied bimonthly from September 2003 to July 2004 in a macrotidal mangrove creek at Curuçá estuary, Brazil. Feeding activity and relative importance of prey groups were assessed in 528 and 226 specimens (6.2 to 36.0 cm total length), respectively, using stomach contents. A total of 1 820 specimens were caught. The fish left the creek with an average of 2.2 % of their body weight in prey. Feeding activity was lower in the dry season (September and November 2003) than in the rainy season (January to May 2004). The diet was dominated by Ocypodidae and Grapsidae. Feeding strategies of the pemecou sea catfish indicated a slight variation between the diets of adults and juveniles; however; the main factor leading to diversification in the diet were the seasons. Opportunistic feeding behavior was observed in the dry season, shifting to more specialized feeding in the wet season. This temporal diet shift may be explained by the environmental seasonal variations (e.g. transparency of the water, high water level) in the intertidal mangrove creek habitat. Rev. Biol. Trop. 56 (2): 861-873. Epub 2008 June 30.

Estudiamos la ecología trófica del bagre guatero Sciades herzbergii, con periodicidad bimestral, desde septiembre de 2003 a julio de 2004, en un canal de marea del estuario del río Curuçá, norte de Brasil. Del total de 1820 ejemplares capturados, analizamos la actividad alimentaría y la importancia de las diferentes fuentes de alimento por evaluación de los contenidos estomacales de 528 y 226 ejemplares (longitud corporal 6,2 a 36,0 cm), respectivamente. S. herzbergii sale del canal de marea con un valor promedio de 2,2 % de su peso corporal como alimento. El ritmo alimentario fue menor durante el período seco (septiembre a noviembre de 2003) que en el lluvioso (enero a mayo de 2004). Los análisis de los contenidos estomacales de 226 ejemplares indicaron una dieta con predominio de Ocypodidae y Grapsidae. Las estrategias alimentarías de S. herzbergii mostraron pequeñas diferencias entre las dietas de los adultos y de los jóvenes, pero la variación estacional fue el factor que mejor definió la diversificación de la dieta. En el período seco hubo un comportamiento oportunista en la alimentación, cambiando a una dieta mas especializada durante el período lluvioso. Esta variación temporal en la dieta corresponde con la variación estacional en los hábitats del canal de marea.

Redescrição de Genidens barbus (Lacépède, 1803) e Genidens machadoi (Miranda-Ribeiro, 1918), Bagres Marinhos (Siluriformes, Ariidae) do Atlântico Sul Ocidental

Variation in the pattern of the vomero-palatine tooth patches of Genidens barbus and Genidens machadoi is reviewed and the species redescribed based on the analysis of 46 morphological characters. Genidens machadoi can be distinguished from Genidens barbus by: the notched lateral margin of the sphenotic (vs. lateral margin of the sphenotic straight); the cephalic shield narrowest in the sphenotic (vs. cephalic shield narrowest in the frontal); distance between the lateral margin of the cephalic shield, at narrowest portion, and the posterior margin of the orbit 0.681.0 of the smallest width of the cephalic shield (vs. 1.21.7); width of the posterior extremity of the supra-occipital process 2.03.4 of the length of the supra-occipital process (vs. 3.34.7); one or two groups of tooth patches on roof of mouth, anterior patch small and round, posterior patch oval, sometimes confluent or fused with the front group (vs. patches a with horseshoe shape, patches totally fused or divided in confluent groups, always with a posterior projection); longest length of the tooth patches 3.24.9 of the height of the head (vs. 1.93.4); granulation on cephalic shield coarse and irregularly distributed (vs. smooth and distributed in regular series).

A variação no padrão das placas de dentes vômero-palatinas de Genidens barbus e Genidens machadoi é revista e as espécies redescritas com base na análise de 46 caracteres morfológicos. Genidens machadoi pode ser diferenciada de Genidens barbus pela: margem lateral do esfenótico recortada (vs. margem lateral do esfenótico retilínea); escudo cefálico mais estreito na região dos esfenóticos (vs. escudo cefálico mais estreito na região dos frontais); distância entre a margem lateral do escudo cefálico, na porção mais estreita, e a margem posterior da órbita cabendo 0,681,0 na menor largura do escudo cefálico (vs. 1,21,7); menor largura do processo occipital, na porção posterior, cabendo 2,03,4 no comprimento do processo occipital (vs. 3,34,7); um ou dois pares de placas de dentes na região do palato, par anterior arredondado e pequeno, par posterior ovalado às vezes confluente ou fusionado com o par anterior (vs. placas de dentes na região do palato formando um conjunto com aspecto de uma ferradura, as placas totalmente fusionadas ou confluentes e distintas, mas sempre com uma projeção posterior); maior comprimento das placas de dentes cabendo 3,24,9 na altura da cabeça (vs. 1,93,4); granulação no escudo cefálico espessa e irregularmente distribuída (vs. fina e distribuída em série regulares).

Redescrição de Genidens barbus (Lacépède, 1803) e Genidens machadoi (Miranda-Ribeiro, 1918), Bagres Marinhos (Siluriformes, Ariidae) do Atlântico Sul Ocidental

Variation in the pattern of the vomero-palatine tooth patches of Genidens barbus and Genidens machadoi is reviewed and the species redescribed based on the analysis of 46 morphological characters. Genidens machadoi can be distinguished from Genidens barbus by: the notched lateral margin of the sphenotic (vs. lateral margin of the sphenotic straight); the cephalic shield narrowest in the sphenotic (vs. cephalic shield narrowest in the frontal); distance between the lateral margin of the cephalic shield, at narrowest portion, and the posterior margin of the orbit 0.681.0 of the smallest width of the cephalic shield (vs. 1.21.7); width of the posterior extremity of the supra-occipital process 2.03.4 of the length of the supra-occipital process (vs. 3.34.7); one or two groups of tooth patches on roof of mouth, anterior patch small and round, posterior patch oval, sometimes confluent or fused with the front group (vs. patches a with horseshoe shape, patches totally fused or divided in confluent groups, always with a posterior projection); longest length of the tooth patches 3.24.9 of the height of the head (vs. 1.93.4); granulation on cephalic shield coarse and irregularly distributed (vs. smooth and distributed in regular series).

A variação no padrão das placas de dentes vômero-palatinas de Genidens barbus e Genidens machadoi é revista e as espécies redescritas com base na análise de 46 caracteres morfológicos. Genidens machadoi pode ser diferenciada de Genidens barbus pela: margem lateral do esfenótico recortada (vs. margem lateral do esfenótico retilínea); escudo cefálico mais estreito na região dos esfenóticos (vs. escudo cefálico mais estreito na região dos frontais); distância entre a margem lateral do escudo cefálico, na porção mais estreita, e a margem posterior da órbita cabendo 0,681,0 na menor largura do escudo cefálico (vs. 1,21,7); menor largura do processo occipital, na porção posterior, cabendo 2,03,4 no comprimento do processo occipital (vs. 3,34,7); um ou dois pares de placas de dentes na região do palato, par anterior arredondado e pequeno, par posterior ovalado às vezes confluente ou fusionado com o par anterior (vs. placas de dentes na região do palato formando um conjunto com aspecto de uma ferradura, as placas totalmente fusionadas ou confluentes e distintas, mas sempre com uma projeção posterior); maior comprimento das placas de dentes cabendo 3,24,9 na altura da cabeça (vs. 1,93,4); granulação no escudo cefálico espessa e irregularmente distribuída (vs. fina e distribuída em série regulares).

Community ecology of the metazoan parasites of white sea catfish, Netuma barba (Osteichthyes: Ariidae), from the coastal zone of the state of Rio de Janeiro, Brazil

Between March 2000 and April 2001, 63 specimens of N. barba from Angra dos Reis, coastal zone of the State of Rio de Janeiro (23°0'S, 44°19'W), Brazil, were necropsied to study their infracommunities of metazoan parasites. Fifteen species of metazoan parasites were collected: 2 digeneans, 1 monogenean, 2 cestodes, 1 acantocephalan, 2 nematodes, 6 copepods, and 1 hirudinean. Ninety-six percent of the catfishes were parasitized by at least one metazoan parasite species. A total of 646 individual parasites was collected, with mean of 10.3 ± 16.6 parasites/fish. The copepods were 37.5% of the total parasite specimens collected. Lepeophtheirus monacanthus was the most dominant species and the only species with abundance positively correlated with the host total length. Host sex did not influence parasite prevalence or mean abundance of any species. The mean diversity in the infracommunities of N. barba was H = 0.130 ± 0.115 with no correlation with host's total length and without differences in relation to sex of the host. One pair of endoparasites (Dinosoma clupeola and Pseudoacanthostomum floridensis) showed positive association and covariation between their abundances and prevalences. The parasite community of N. barba from Rio de Janeiro can be defined as a complex of species with low prevalence and abundance and with scarcity of interspecific associations. However, because of both the presence of assemblages of sympatric ariid species as well as the spawning behavior characteristic of these fishes, additional comparative studies of the parasite component communities of ariids are necessaries to elucidate this pattern.

Entre março de 2000 e abril de 2001, 63 espécimes de N. barba, provenientes de Angra dos Reis, litoral do Estado do Rio de Janeiro (23°0'S, 44°19'W), Brasil, foram necropsiados para estudo de suas infracomunidades de metazoários parasitos. Foram coletadas 15 espécies de metazoários parasitos: 2 digenéticos, 1 monogenético, 2 cestóides, 1 acantocéfalo, 2 nematóides, 6 copépodes e 1 hirudíneo. Constatou-se que 96% dos bagres estavam parasitados por, no mínimo, uma espécie de parasito. Um total de 646 parasitos foram coletados, com média de 10,3 ± 16,6 parasitos por peixe. Os copépodes representaram 37,5% do total de espécies coletadas. Lepeophtheirus monacanthus foi a espécie dominante e a única com abundância correlacionada positivamente com o comprimento total dos hospedeiros, cujo sexo não influenciou a prevalência e a abundância média parasitária de nenhuma espécie. A diversidade média das infracomunidades de N. barba foi de H = 0,130 ± 0,115, sem apresentar correlação com o comprimento total dos hospedeiros e sem diferenças em relação ao sexo destes. Um par de endoparasitos (Dinosoma clupeola e Pseudoacanthostomum floridensis) apresentou associação e covariação positiva entre suas abundâncias e prevalências. A comunidade parasitária de N. barba do litoral do Estado do Rio de Janeiro pode ser definida como um complexo de espécies com baixa prevalência e abundância e escassez de associações interespecíficas. Entretanto, em razão da presença de assembléias de espécies simpátricas de arídeos e do comportamento reprodutivo característico desses peixes, são necessários estudos comparativos adicionais das comunidades parasitárias componentes dos arídeos para confirmar esse padrão.