CLINOSTOMUM MARGINATUM (BRAUN, 1899) Y AUSTRODIPLOSTOMUM COMPACTUM (LUTZ, 1928) METACERCARIAS CON POTENCIAL ZOONÓTICO EN PYGOCENTRUS NATTERERI (KNER, 1858) (CHARACIFORMES: SERRASALMIDAE) DE LA AMAZONÍA CENTRAL, BRASIL

El presente estudio investigó la presencia de helmintos en filetes de la piraña roja, Pygocentrus nattereri (Kner, 1858), alertando sobre un posible potencial zoonótico de su consumo en la forma in natural. Fueron examinados 40 peces capturados en lagos de varzea del Río Solimões, localizados entre los Municipios de Coari y Manaus en la Amazonía Central, Brasil. Todos los peces analizados fueron adultos y presentaban quiste amarillos en la musculatura del filete. Fueron encontrados 69 quistes e identificadas las metacercárias de las especie Clinostomum marginatum (Braun, 1899) (66 quistes) y Austrodiplostomum compactum (Lutz, 1928) (3 quistes). El análisis demuestra una mayor susceptibilidad de P. nattereri para metacercárias de C. marginatum. El hecho de haber sido encontradas metacercárias en filetes de P. nattereri, genera una situación de riesgo, remitiendo la preocupación en cuanto a su consumo en la forma cruda, no debiendo ser consumido sin una adecuada inspección, procesamiento y congelamiento, considerando que el cebiche es un alimento bastante consumido, principalmente en la región fronteriza del Alto Solimões en la Amazonía Occidental.

Age-associated hemogram and ultrastructural leukocyte morphology in Pygocentrus nattereri (Characiformes: Serrasalmidae) from the Brazilian Pantanal

ABSTRACT Pygocentrus nattereri is a carnivorous fish widely distributed in the Brazilian wetland and occupies different river strata. Based on the sexual maturity, the standard length (SL) has been used to categorize age and physiological attributes. However, hematological parameters and their relationship with age and growth features are unknow. Here, the aim was to evaluate the hematological profile and leukocyte data of juvenile and adult specimens, associating it with SL. Specimens of both sexes were weighted, and SL were measured for classify as juveniles (SL ≤16.0 cm) and adults (SL ≥16.1 cm). Blood was collected to perform the hemogram, for leukocyte quantification and ultrastructural descriptions. In general, hemogram values and leukocyte, lymphocyte, and monocyte counts were high in juveniles. Hemogram variables were negatively correlated with SL. Thrombocyte and neutrophil counts were higher in adults than in juveniles. SL was correlated with leukogram variables. Ultrastructural analysis showed that granular leukocyte count in P. nattereri was similar another fishes. PAS-positive granular leukocytes are slightly smaller than neutrophils and are characterized by dense elongated and semi-lunar shapes in the cytoplasm. Our results suggest that age-based SL may be useful for the analysis of the relationship between P. nattereri health status and wetland aquatic environments.

Reproductive biology of seven fish species of commercial interest at the Ramsar site in the Baixada Maranhense, Legal Amazon, Brazil

The purpose of this study is to determine the parameters of the reproductive biology of seven commercial species at the Ramsar Site of the Baixada Maranhense to support fisheries management measures. The collections were carried out between 2012 and 2016. The reproductive period, sex ratio, weight-length relationship and first sexual maturity were evaluated for seven species of commercial importance. The sex ratio showed that females are predominant for all species, except for Plagioscion squamossissimus. The weight-length relationship indicated a greater investment in weight for Cichla monoculus and Hassar affinis, and a greater investment in length for Hoplias malabaricus, Plagioscion squamosissimus, Prochilodus lacustris, Pygocentrus nattereri, and Schizodon dissimilis. The reproductive activity of the species was predominant in the rainy season, but C. monoculus, H. malabaricus and P. lacustris showed the ability to reproduce in both seasons. As management measures for the region, it is suggested a change in the closed fishing season established by IBAMA, from December 1 to April 30, to ensure the protection of all commercial species in this study.

Molecular characterization and genetic relationships of seven piranha species of the genera Serrasalmus and Pygocentrus (Characiformes: Serrasalmidae) from Paraná-Paraguay, São Francisco and Tocantins River basins in Brazil

Genetic and phylogenetic relationships among seven piranha species of the genera Serrasalmus and Pygocentrus from the Paraná-Paraguay, São Francisco and Tocantins River basins were evaluated in the present study by partial sequences of two mitochondrial genes, Cytochrome b and Cytochrome c Oxidase I. Phylogenetic analysis of Maximum-Likelihood and Bayesian inference were performed. Results indicated, in general, greater genetic similarity between the two species of Pygocentrus (P. nattereri and P. piraya), between Serrasalmus rhombeus and S. marginatus and between S. maculatus, S. brandtii and S. eigenmanni. Pygocentrus nattereri, S. rhombeus and S. maculatus showed high intraspecific genetic variability. These species have each one, at least two different mitochondrial lineages that, currently, occur in sympatry (S. rhombeus) or in allopatry (P. nattereri and S. maculatus). Species delimitation analysis and the high values of genetic distances observed between populations of S. rhombeus and of S. maculatus indicated that each species may corresponds to a complex of cryptic species. The non-monophyletic condition of S. rhombeus and S. maculatus reinforces the hypothesis. The geographic distribution and the genetic differentiation pattern observed for the piranha species analyzed herein are discussed regarding the geological and hydrological events that occurred in the hydrographic basins.

BIODIVERSIDAD DE MONOGENÓIDEOS DE LA PIRAÑA ROJA PYGOCENTRUS NATTERERI (KNER, 1958) (CHARACIFORMES: SERRASALMIDAE) EN LA AMAZONÍA CENTRAL: OCURRENCIA Y TAXONOMÍA

Fue descrita la fauna de parásitos de la clase Monogenoidea en Pygocentrus nattereri capturados en seis lagos inundables del río Amazonas en la Amazonía Central: Baixio Negro Iauara, Ananá, Campina y Maracá, localizados entre las ciudades de Manaus y Coari, Brasil. Fueron adicionadas informaciones a las descripciones originales de las especies ya descritas y fueron citadas nuevas ocurrencias. Fueron capturados 355 P. nattereri durante los meses de marzo, junio, septiembre y diciembre de 2008. Los peces median 15,4 cm ± 3,5 y pesaban 230,9 g ± 2,7. Fueron colectados y determinados, hasta el menor taxón posible 50,987 especímenes de Monogenoidea, divididos en siete géneros y 16 especies. Fue encontrada una nueva especie de Anacanthorus sp., sin embargo el número de individuos fue muy bajo para hacer la descripción correspondiente. Fue realizado el primer registro de una especie de la familia Gyrodactylidae parasitando P. nattereri. La gran diversidad de especies de Monogenoidea que utilizan a P. nattereri como huésped indica la importancia del rol que esta especie de pez posee para mantener la biodiversidad en los lagos inundables de la Amazonía Central.

COPEPODOS (CRUSTACEA: ERGASILIDAE) PARÁSITOS DE PECES DE LAGOS INUNDABLES DE LA AMAZONÍA CENTRAL, BRASIL

Fueron examinadas especímenes de nueve especies de peces provenientes de lagos inundables de la Amazonía Central, Brasil, de los cuales fueron identificados 1812 copépodos parásitos (1694 en las branquias y 118 en las narinas) correspondientes a 15 especies de siete géneros de la familia Ergasilidae. Las especies identificadas fueron: Acusicula pellonidis, Amplexibranchius bryconis, Ergasilus turucuyus y Miracetyma piraya en las branquias de Astronotus ocellatus; Therodomas elongatus en las narinas de Astronotus crassipinnis; Acusicola tucunarense y Ergasilus coatiarus en las branquias de Cichla monoculus; Gamidactylus jaraquensis, y Rhinergasilus piranhus en las narinas de Colossoma macropomum; Amplexibranchius bryconis, Ergasilus jaraquensis y Miracetyma etimaruya en las branquias de Potamorhina latior; Ergasilus yumaricus y Miracetyma piraya en las branquias de Pygocentrus nattereri; Rhinergasilus piranhus en las narinas de Pygocentrus nattereri; Ergasilus sp2 y Miracetyma kawa en las branquias de Raphiodon vulpinus; Amplexibranchius bryconis y Ergasilus jaraquensis en las branquias de Serrasalmus altispinis y Gamidactylus jaraquensis y Rhinergasilus piranhus en las narinas de S. altispinis. El presente estudio determinó nuevos registros y ocurrencias de diferentes especies de copépodos parásitos en otros hospederos y otras áreas geográficas anteriormente no registradas en Brasil.

DIPLOSTOMUM (AUSTRODIPLOSTOMUM) COMPACTUM (LUTZ, 1928) (PLATYHELMINTHES, DIGENEA) METACERCARIA LIBRE EN LOS OJOS DE LOS PECES DE LOS LAGOS DE INUNDACIONES AL RIO INFERIOR DE SOLIMÕES, BRASIL

Doscientos ochenta y nueve peces de 24 especies y cuatro órdenes fueron capturados en los lagos Catalão, Preto y Poraquê en la estación seca. Trece especies fueron parasitadas por metacercarias libres de Diplostomum (Austrodiplostomum) compactum (Lutz, 1928) en los ojos: Pygocentrus nattereri Kner, 1858, Serrassalmus elongatus Kner, 1858 (Serrasalmidae); Acestrorhynchus falcirostris (Cuvier, 1819) (Characidae); Satanoperca jurupari (Heckel, 1840); Geophagus surinamensis (Bloch, 1791), Crenicichla johanna Heckel, 1840, Mesonalta festivus (Heckel, 1840) (Cichlidae); Plagioscion squamosissimus Heckel, 1840 (Sciaenidae); Loricariichthys acutus Valenciennes, 1840, Pterygoplichthys pardalis (Castelnau, 1855) (Loricariidae); Pimelodus bloch Valenciennes, 1840 (Pimelodidae) y Pellona castellneana Valenciennes, 1847 (Pristigasteridae). Se recogieron un total de 1065 metacercarias libres de D. (A.) compactum. Plagioscion squamosissimus fue la especie con mayor abundancia de metacercarias con 640 individuos. Las especies de peces bentónicos fueron más parasitadas que las pelágicas.

The Piranha Genome Provides Molecular Insight Associated to Its Unique Feeding Behavior

The piranha enjoys notoriety due to its infamous predatory behavior but much is still not understood about its evolutionary origins and the underlying molecular mechanisms for its unusual feeding biology. We sequenced and assembled the red-bellied piranha (Pygocentrus nattereri) genome to aid future phenotypic and genetic investigations. The assembled draft genome is similar to other related fishes in repeat composition and gene count. Our evaluation of genes under positive selection suggests candidates for adaptations of piranhas’ feeding behavior in neural functions, behavior, and regulation of energy metabolism. In the fasted brain, we find genes differentially expressed that are involved in lipid metabolism and appetite regulation as well as genes that may control the aggression/boldness behavior of hungry piranhas. Our first analysis of the piranha genome offers new insight and resources for the study of piranha biology and for feeding motivation and starvation in other organisms.

Nematofauna of red piranha Pygocentrus nattereri (Kner, 1958) (Characiformes: Serrasalmidae) from Amazonia, Brazil

Between March and October 2008, 355 specimens of Pygocentrus nattereri were collected from the lowland lakes of Central Amazonia, Brazil, to study their nematode fauna. A total of 1.116 specimens of Nematoda were collected, belonging to six species. Procamallanus (Spirocamallanus) inopinatus was the species with the highest parasite indices. Larvae of Anisakis sp. have zoonotic potential and were found parasitizing the intestine and liver of Pygocentrus nattereri. Some of these nematode species were new records for the host P. nattereri. The diversity of nematodes that use P. nattereri as a host indicates the important role of this fish species in the maintenance of these six nematode species in the lowland lakes of Central Amazonia.