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The present study aimed at describing and evaluating the fauna of Anisakidae and Raphidacarididae nematodes of lutjanid fish (snappers) from the Brazilian northeastern coast unloaded at the city of Aracaju, capital of the State of Sergipe. A total of 186 lutjanids of 5 different species were analyzed including 69 Lutjanus analis, 51 L. vivanus , 29 Ocyurus chrysurus, 23 L. synagris, and 14 L. jocu. Nematode specimens found in the viscera of these fish were clarified with lactophenol. Illustrations of each of these specimens were prepared to help identify these samples and compose their taxonomic description and classification. At necropsy, 3,183 nematodes belonging to two families were collected from fish viscera which included the following: Anisakidae: Anisakis, Terranova , Contracaecum, and Goezia; Raphidascarididae: Raphidascaris (Ichthyascaris) and Hysterothylacium . A total of six genera of nematodes were found at postmortem examination of which adult worms of only three genera (Goezia, Raphidascaris and Hysterothylacium) were detected in the fish examined. Larvae of Terranova sp. were found only in the musculature of O. chrysurus . Most of the nematode larvae were present in the mesentery and organs of the fish necropsied. Therefore, the zoonotic potential of these nematodes cannot be ruled out. There was a significant negative correlation between the intensity of parasitism by anisakids and the total body length of O. chrysurus; the intensity of parasitism was greater in smaller and shortef fish. There was a significant positive correlation between the abundance of these parasites and the length of L. synagris; the presence of these parasites increased according to the fish’s body length. To the authors’ knowledge, these are the first records of Raphidascaris (Ichthyascaris ) sp. and Hysterothylacium sp. in L. vivanus , of Terranova sp. in O. chrysurus and L. jocu, and of Goezia sp. in L. analis. These novel findings add the Brazilian northeast coast and the State of Sergipe in the geographic distribution of these parasites in the country. Resumo O objetivo deste trabalho é descrever e avaliar a fauna de Anisakidae e Raphidacarididae de peixes lutjanídeos do litoral nordeste do Brasil desembarcados na cidade de Aracaju, capital do estado de Sergipe. Foram analisados 186 lutjanídeos das espécies Lutjanus analis 69, L. vivanus 51, Ocyurus chrysurus 29, L. synagris 23 e L. jocu 14. Exemplares dos nematodas encontrados nas vísceras foram clarificados em lactofenol e ilustrados para auxiliar na identificação e compor a descrição taxonõmica. Foram coletados 3.183 nematodas das vísceras dos peixes, pertencentes a duas famílias: Anisakidae: Anisakis, Terranova, Contracaecum e Goezia; e Raphidascarididae: Raphidascaris (Ichthyascaris) e Hysterothylacium. Totalizando seis gêneros encontrados, apenas nos três últimos gêneros foram encontrados vermes em estágio adulto. Apenas em O. chrysurus foram encontradas larvas de Terranova sp. na musculatura. A maioria das larvas estava restrita ao mesentério e órgãos dos peixes, e em grande intensidade não podendo se descartar o potencial zoonótico. Observou-se uma correlação significativa negativa entre a intensidade anisakídeos e o comprimento total de O. chrysurus, onde a intensidade dos parasitas é maior em peixes de menor comprimento e uma correlação significativa positiva entre a abundância desses mesmos parasitos com o comprimento de L. synagris, onde a presença dos parasitas aumenta conforme o comprimento do peixe. Esse é o primeiro registro de Raphidascaris ( Ichthyascaris) sp. e Hysterothylacium sp. em L. vivanus ; de Terranova sp. em O. chrysurus e L. jocu e Goezia sp. em L. analis, adicionando o litoral nordeste do Brasil e o estado de Sergipe na distribuição geográfica desses parasitos.

Diplostomum ardeae Dubois, 1969 has seldom been reported since its description from the great blue heron (Ardea herodias L., 1758) in the USA. Sequences obtained in this study from the barcode region of cytochrome c oxidase 1 (CO1) in diplostomids from black-crowned night heron (Nycticorax nycticorax (L., 1758)) in Puerto Rico matched data from D. ardeae from A. herodias in the type region. We also obtained DNA barcodes from morphologically similar diplostomids from a rufescent tiger heron (Tigrisoma lineatum (Boddaert, 1783)) and from metacercariae from eye lenses of Trachelyopterus galeatus (Linnaeus, 1766) from the Parana River basin in Argentina and Brazil, respectively. Barcodes matched (97–100% identity) in these South American adult and larval specimens as well as in recently published sequences from metacercariae from 11 other siluriform fishes from the same region. Barcodes from the South American species, which we describe as Diplostomum lunaschiae n. sp., differed from those of D. ardeae by 7.2–9.8%, and the new species differs from D. ardeae in its size, pharynx:oral sucker length ratio, egg:body length ratio, and distribution of vitellaria. As in prior phylogenetic analysis of CO1 sequences, both D. ardeae and D. lunaschiae n. sp. were not associated with Diplostomum. In more character-rich analyses of nuclear rDNA and of mitochondrial genomes, D. ardeae was an early divergent member of clades of species of Diplostomum. Consequently, we continue to consider D. ardeae and D. lunaschiae n. sp. members of Diplostomum, in contrast to recent suggestions that these species may belong to a different genus.

Parasitic isopod species are poorly known in the northeastern coast of Brazil. In this sense, this study presents novel records of Isopoda of the families Aegidae, Cymothoidae, and Corallanidae. A total 69 specimens of Lutjanus analis and 19 of Lutjanus jocu, of which 46 isopods from 3 different species were collected, i.e. Rocinela signata, Cymothoa excisa, and Excorallana richardsoni. The species R. siganata and E. richardsoni are reported for the first time in L. jocu. A significant relationship between the parasite R. signata and the size of the fish L. jocu was also observed. The isopod C. excisa is considered an incidental finding in L. analis. To the authors’ knowledge, this is the first report of this species in fish from Brazil. The three species of isopods are new occurrences in the State of Sergipe, northeast region of the country. An additional morphological characteristic observed in the dorsal setae of pleotelson in specimens of E. richardsoni was that one end of this structure wws bifid. This information contributes to the current body of knowledge of the morphology of this particular species.

Lutjanids are marine fish and commonly inhabit coral reefs, which have migratory habits and feed in a general way, due to these characteristics, are susceptible to infections by parasites, such as cuculanid nematodes. This work aimed to report for the first time, the occurrence of Dichelyne (Dichelyne) bonacii in Brazil, in two new hosts, Lutjanus analis and Rhomboplites aurorubens, acquired from local artisanal fishermen at the Aracaju city public fishing terminal (10 ° 54’17 “S37 ° 2’56” W), northeast coast of Brazil. Adult nematodes were collected from the intestinal tract of the hosts, clarified in Aman’s Lactophenol and were briefly described here. Three adult males and five gravid females were found, indicating that the two species of fish acted as definitive hosts. Currently, this species of parasite has been reported only from fish collected in the coast of Mexico, which makes this work the first record of this parasite in Brazilian coastal waters. The results show that probably the range of hosts and the distribution of D. (Dichelyne) bonacii is not as restricted as data pointed in the literature, being a little wider, extending also to waters that bathe the Brazilian coast.

Three species of snappers from artisanal, small-scale fisheries were examined for the presence of parasites. A total of 139 lutjanid fish were collected: 69 specimens of Lutjanus analis, 47 specimens of Lutjanus vivanus, and 23 specimens of Lutjanus synagris. Encysted plerocercoid of trypanorhynch cestodes found at necropsy in the viscera of snappers were sampled for parasitological analysis. These plerocercoid larvae belong to the genera Floriceps, Pseudogrillotia , and Oncomegas. Although these parasites do not have any zoonotic potential, fish with heavy loads of plerocercoids are rejected during inspection as they compromise meat hygiene. Our findings suggest that light larval cestode infections in lutjanids would not lead to consumer rejection of the food product. The occurrence of Floriceps sp. in L. analis and in L. synagris, of Pseudogrillotia sp. in L. vivanus and in L. synagris , and of Oncomegas sp. in L. synagris are new findings in these fish species. These parasites are new to these fish species and have not been reported in snappers from the northeast coast of Brazil. The results contribute to the existing body of knowledge about the parasitic fauna of fish and its distribution along the coastline of Brazil.

Schistosomiasis, which is caused by trematodes of the genus Schistosoma and by the species Schistosoma mansoni in Brazil, is transmitted primarily by Biomphalaria glabrata mollusks. Infections occur in humans and mollusks in freshwater environments contaminated with feces from infected humans. This study aimed to evaluate potential foci of schistosomiasis based on the identification of infection sites for the snails, factors that increased the human infection probability of S. mansoni infection, and the relationship of the disease with abiotic, biotic, and sociocultural factors. The study was conducted in an urban area on the northeast coast of Brazil; this location was chosen based on the following factors: the presence of B. glabrata, nearby freshwater, and the absence of sewer treatment. A parasitological analysis was performed to evaluate infections of the mollusks and residents inside the perimeter defined by the collection points. Questionnaires were applied to obtain demographic data and to identify behaviors that led to human infection. To verify the contamination of freshwater by human feces, a microbiological analysis of the water was performed at the mollusk collection points to determine the rate of contamination with fecal coliforms. A total of 10,270 B. glabrata mollusks were collected between August 2013 and August 2014, of which 8.8% were positive for S. mansoni; the prevalence ranged from 0 to 34.5% over the study period. A total of 232 coprological samples from the residents were analyzed. The S. mansoni infection prevalence rate was 16.4%, and the S. mansoni parasitic load in the infected residents was 54.9 eggs per gram of feces on average. Males were more affected by the parasite, especially in the 8-17-year-old age range. Thermotolerant coliforms were observed at the mollusk collection sites, which indicated that freshwater and sewage were in continuous contact. This contamination indicated poor sanitary conditions, as was previously observed, which could be combined with detrimental behavior due to the residents' habits. These conditions cause a predisposition for both intermediate and definitive infections of the hosts by creating a socioenvironmental scenario that is conducive to the formation and maintenance of potential schistosomiasis foci. This and similar areas deserve special attention from the government with an aim of improving sanitation services and local resident knowledge to prevent future contamination.

In Brazil, more than 150 non-native fish species have been introduced either intentionally or unintentionally, mainly due to aquaculture, fishery improvement and ornamental trade. The non-native jaguar guapote Parachromis managuensis was recorded in two artificial ponds, four rivers, one stream and two reservoirs, ecosystems belonging to the Una, Ipojuca, Capibaribe and Pajeu River basins, Pernambuco, northeastern Brazil. The sampling period was between October 2006 and July 2015. A total of 376 individuals of P. managuensis was captured by seines, casting nets and gillnets. This species may have been introduced in the study sites by accidental release during pond drainage in fish farms, stocking for the purpose of animal protein production or by aquarium dumping. The presence of various ontogenetic life stages in all studied environments is a strong evidence that the species is established. Seven management actions are proposed to prevent further introductions of P. managuensis in other environments of the region.Keywords: exotic, bioinvasion, introduction, aquarism, freshwater fish.

Traira (Hoplias malabaricus) is a neotropical fish that is widely distributed in freshwater environments in South America. In the present study, we documented the occurrence of metacercariae of Austrodiplostomum spp. (Diplostomidae) in the eyes and cranial cavity of H. malabaricus and described parasite-induced behavioral changes in the host. The fish were collected from the upper São Francisco River, in the Serra da Canastra mountain range, Minas Gerais, transported alive to the laboratory, observed for 2 weeks, and subsequently examined for parasites. Of the 35 fish examined, 28 (80 %) had free metacercariae in the vitreous humor (mean intensity=95.4; mean abundance=76.3), and 24 (68.57 %) had free metacercariae in the cranial cavity, mainly concentrated below the floor of the brain, at the height of the ophthalmic lobe (mean intensity=12.91; mean abundance=8.85). Specimens of H. malabaricus with a high intensity of infection in the brain displayed changes in swimming behavior.

Parasites are important components of communities and constitute great part of the biological diversity found in ecosystems, providing valuable information about their hosts and the environment in which they live. However, despite its importance, parasitic diversity is still not well known in some regions of Brazil, especially with respect to fish parasites in the Northeast Region. The present study aims to perform the survey of gill parasites of fish from two tropical estuaries located in northeastern Brazil: Paraíba and Mamanguape rivers. Two collections were made in each estuary, one during the dry period (November / 2013) and the other during the rainy season (July / 2014). The fish were caught using a beach seine net, dragged along the main channel margin. After the identification, biometry and necropsy of the fish, their parasites were collected, stored and identified. For each species of parasite, the values ​​of prevalence, mean intensity and mean abundance were calculated. Of the 882 examined fish, belonging to four species, 145 were parasitized by at least one species of parasite. In total, 18 taxa of parasites of the groups Monogenea, Digenea, Nematoda, Copepoda and Isopoda were recorded, being the copepod Acusicola brasiliensis the most abundant species of parasite.

Larvae (metacercariae) in some species of Diplostomidae (Platyhelminthes: Digenea) inhabit fish eyes and are difficult to identify to species based on morphology. DNA barcoding has clarified the diversity and life cycles of diplostomids in North America, Europe and Africa, but has seldom been used in parasites sampled in large numbers or at large spatial scales. Here, distance-based analysis of cytochrome c oxidase 1 barcodes and, in some specimens, internal transcribed spacer (ITS-1, 5.8S, ITS-2) sequences was performed for over 2000 diplostomids from Africa, the Middle East, Europe, Asia and the Americas. Fifty-two species of Diplostomum, Tylodelphys and Austrodiplostomum (Digenea: Diplostomidae) were distinguished. The 52 species comprise 12 identified species, six species in two species complexes and 34 putative species, and 33/52 had been delineated in previous studies. Most (23/40) of the unidentified, putative species distinguished by cytochrome c oxidase 1 distances were supported by at least one additional line of evidence. As the intensity of sampling of the 52 species increased, variation in cytochrome c oxidase 1 decreased between and increased within species, while the spatial scale at which species were sampled had no effect. Nonetheless, variation between species always exceeded variation within species. New life-cycle linkages, geographic and host records, and genetic data were recorded in several species, including Tylodelphys jenynsiae, Tylodelphys immer and Diplostomum ardeae. Species of Diplostomum inhabiting the lens are less host-specific and less numerous than those infecting other tissues, suggesting that reduced immune activity in the lens has influenced rates of speciation.

The prevalence of Clinostomum complanatum Rudolphi, 1814 (Digenea, Clinostomidae) in fishes Loricariichthys platymetopon, Parauchenipterus galeatus and Hoplosternum littorale, which are second intermediate hosts, was studied at the floodplain of the high Paraná River, Brazil. Season (alternation flood-drought), habitat (lentic and semi-lotic), and sex were not related to its prevalence. For L. platymetopon, the immature and smaller fish had the lowest prevalence, whilst the opposite was observed for P. galeatus and H. littorale. This suggests that the probability of being predated is unchanged by parasitism for L. platymetopon; thus, a cumulative effect of repeated infections is observed; for the two other species, the highest parasitised fish may have higher predation mortality rates. While H. littorale is the preferred item in birds' diet, L. platymetopon is the most abundant fish species and has the highest C. complanatum prevalence, which makes it the most likely path of transmission to the bird, the definitive hosts of C. complanatum.

La fixation de Clinostomum sp. a l'oesophage de son hote definitif Ardea cocoi (Oiseau) est decrite. Le parasite s'attache a la couche muqueuse de l'oesophage par l'acetabulum, la ventouse orale et la partie anterieure du corps. La couche muqueuse de l'œsophage de l'Oiseau recouverte par la ventouse orale presente une necrose intense et liquefiante, mais vraisemblablement ce recouvrement ne contribue pas de facon significative a la fixation du parasite. La partie anterieure du corps du parasite entourant la ventouse orale est juxtaposee a la couche muqueuse de l'œsophage montrant une adhesion parfaite des deux surfaces. En conclusion, le mecanisme principal intervenant dans la fixation du parasite a l'oesophage de l'hote est fourni par l'acetabulum et par la juxtaposition de la partie anterieure du corps du parasite et de la surface oesophagienne de l'hote.

The life cycle of the digenetic trematode Clinostomum complanatum was studied on the floodplain of the high Paraná river, Brazil. Sampling was done between June 1999 and June 2000. The mollusc Biomphalaria peregrina was the first intermediate host with a prevalence of infection of 0.75%. The fish Loricariichthys platymetopon, Hoplosternum littorale, Parauchenipterus galeatus, Hoplias malabaricus and Loricaria sp. were second intermediate hosts, with the prevalence varying from 2.45% ( H. malabaricus) to 60.8% ( L. platymetopon). The birds Ardea cocoi, Phalacrocorax brasilianus, Egretta alba and Egretta thula were definitive hosts, with the prevalence ranging between 5.5% ( E. thula) and 95% ( A. cocoi). The high prevalences in birds, especially in A. cocoi, suggest some kind of mechanism facilitating the predation of infected fish. The importance of the various hosts is discussed, and it is concluded that the floodplain of the high Paraná river has suitable conditions for the maintenance of the life cycle of C. complanatum.

Minas Gerais is the fourth largest Brazilian state, and has an estimate of 354 native fish species. However, these fish species may be threatened, as this state has the highest rank of fish introductions reported for Brazil and South America. As one from the total of 85 non-native species detected, Lepomis gibbosus was introduced in the 60s to serve both as foragefish and to improve sport fishing. In this study, we evaluated the establishment of L. gibbosus in a shallow lake in the city of Ouro Preto, Doce River basin, state of Minas Gerais, Southeastern Brazil. We collected fish with fishing rods every two months from March 2002-February 2003. Fragments of gonads from a total of 226 females and 226 males were obtained and processed following standard histological techniques; then 5-7μm thickness sections were taken and stained in hematoxylin-eosin. Besides, for each specimen, the biometric measurements included the standard length (SL) and body weight (BW); and the sex ratio was obtained. The reproductive cycle stages were confirmed by the distribution of oocytes and spermatogenic cells. The type of spawning was determined by the frequency distribution of the reproductive cycle stages and ovarian histology. Based on the microscopic characteristics of the gonads, the following stages of the reproductive cycle were determined: one=Rest, two=Mature, three=Spawned for females or Spent for males; males and females in reproduction were found throughout the study period. Post-spawned ovaries containing oocytes in stages one (initial perinucleolar), two (advanced perinucleolar), three (pre-vitellogenic), four (vitellogenic) and post-ovulatory follicles indicated fractionated-type spawning in this species. The smallest breeding male and female measured were 4.6 and 4.9cm standard length, respectively, suggesting stunting. The sex ratio did not vary between males and females along the year and bimonthly, being 1:1. Moreover, L. gibbosus appears to be at stage three of biological invasion: establishment through reproduction. We suggest to deliver information about “non-native species” through lectures in schools, colleges/ universities, NGOs, government and environmental agencies in the cities and villages, in order to try to prevent environmental degradation by the introduction of non-native fish such as L. gibbosus in the region. We also recommend high fines for redhanded, and the import ban of non-native fish species to the region.Se analiza el establecimiento del pez introducido Lepomis gibbosus en una laguna natural de la ciudad de Ouro Preto, Cuenca del Rio Doce, provincia de Minas Gerais, región sureste de Brasil. Cada dos meses se realizaron muestreos con anzuelo y línea, entre marzo 2002-febrero 2003 y se capturaron 226 hembras y 226 machos. Se encontraron hembras y machos en actividad reproductiva durante todo el muestreo. Ovarios con signos de desove con oocitos de diferentes tallas y folículos post-ovulatorios indicaron la puesta parcial para L. gibbosus. La hembra y macho en reproducción más pequeños tenían entre 4.6cm y 4.9cm de longitud, que caracteriza el enanismo. La proporción sexual fue 1:1 y no presentó diferencias bimensuales ni anuales. De las cinco fases del proceso de bioinvasión, se confirmó que L. gibbosus se encuentra en la fase tres, llamada establecimiento a través de la reproducción. Se sugiere aclaración sobre la temática “especie foránea” para evitar la degradación del ambiente con la introducción de peces foráneos en la región.

Scanning electron microscopy is used for the first time to study the surface topography of Ithyoclinostomum dimorphum (Diesing, 1850), collected from Ardea cocoi Linnaeus, 1766 on the floodplain of the upper Parana River Basin, Brazil. The body surface exhibits annular furrows, ridges and sensory papillae but no spines, and the tegument is reticulate. The oral sucker is terminal, bears radial furrows and is surrounded by a collar. The ventral sucker is located close to the oral sucker but lacks a collar. When extruded, the cirrus can be seen to bear papillae in its base, and the aperture of the ejaculatory duct is visible distally. The excretory pore is dorso-subterminal. Various incrustations and secretions are present on the body surface. These detailed observations make it possible for to us speculate on the functional significance of some of our findings in relation to the large size and contractile nature of these worms, and their ability to survive and mate in an apparently hostile environment.