The family Narcinidae has a cosmopolitan distribution; however, its systematic composition and phylogenetic position within Torpediniformes remain poorly understood. This study evaluates the evolutionary and biogeographic history of the family Narcinidae and investigates its distribution patterns using molecular systematics. We analyzed mitochondrial COI sequences from specimens collected along the American coast, combined with publicly available data (GenBank/BOLD) and inferred evolutionary patterns through genetic distance analyses, haplotype network reconstruction and species delimitation methods. Our results demonstrate that electric rays originated in the Central Indo-Pacific realm and reveal two dispersal routes to the American. The first route was from the Central Indo-Pacific to the Pacific Ocean and then the Caribbean Sea, prior to the closure of the Isthmus of Panama. The second route originated in the Central Indo-Pacific, passed through South Africa and then crossed the Atlantic Ocean. The principal torpediniformes lineages diversified between the end of the Cretaceous and the early Palaeocene, with extant narcinid taxa diversifying between 25 and 20 Mya. The present study confirms the nonmonophyly of Narcinidae and corroborates the validity of the genus Narcinops, as well as the restriction of Narcine to American coastal environments. Additionally, three Atlantic species are documented and cryptic lineages are identified within Narcine entemedor and Narcine maculata. These findings improve taxonomic resolution, reveal hidden diversity and provide essential baseline data to support conservation planning, including the identification of management units, prioritization of vulnerable populations and the implementation of more effective monitoring and protection measures for electric rays.

The behavioral plasticity of non-marine elasmobranch species allows these animals to strategically inhabit areas where salinity aligns with their physiological needs. Thus, this study aimed to investigate habitat use by rays in an Amazonian estuary, following a categorization of non-marine species based on the type of environment in which critical life history phases occur. Data on the capture of ray species in fishing weirs were acquired through a monitoring program conducted from March 2011 to April 2012. One hundred and forty-five coastal-estuarine rays, representing seven species, were sampled over 1 year in the estuary, across a salinity range from 12.9 to 41.3 ppt (26.8 ± 11.6 ppt). The dominant presence of neonates and juveniles, constituting approximately 70

This study aimed to identify the most commonly used artisanal fishing gear for capturing elasmobranchs along the coast of Maranhao State, within the Brazilian Amazon Coast. Interviews were conducted with 314 fishers across 17 coastal municipalities using semi-structured questionnaires. These gathered information on vessel characteristics, fishing gear, and elasmobranch species caught in the region. Six types of fishing gear were identified, with gillnets and longlines being the most frequently used. Of the 70 elasmobranch species identified along the Brazilian Amazon Coast, 35 are commonly captured. Among rays, the species most frequently cited by fishers were Hypanus guttatus, Rhinoptera bonasus, Hypanus geijskesi, Aetobatus narinari, Gymnura micrura, Mobula hypostoma, Mobula birostris, and Pseudobatos percellens. For sharks, the most frequently mentioned species included Carcharhinus acronotus, Sphyrna tudes, Carcharhinus leucas, Ginglymostoma cirratum, Galeocerdo cuvier, Rhizoprionodon porosus, and Carcharhinus porosus. Notably, all identified species are susceptible to capture by both gillnets and longlines. To mitigate the impact of these practices on population stocks, particularly for species threatened with extinction, it is essential to develop targeted conservation measures and management plans that address fishing gear, capture areas, and most vulnerable species.

Due to their biological characteristics, elasmobranchs are highly vulnerable to overfishing and habitat degradation. Environmental pollution has also been shown to increasingly affect elasmobranch microbiota composition, yet studies in this area remain scarce. This study aimed to provide a baseline assessment of enteric bacterial species detected in various shark and ray species from the Brazilian Amazon Coast. Enterobacteria samples were collected through cloacal smears from elasmobranchs, cultured, isolated, and biochemically identified (e.g., Vibrio, Aeromonas, Enterobacterales). Polymerase chain reaction (PCR) assays were conducted to identify Aeromonas spp. pathotypes. The most frequently detected enteric bacteria were Klebsiella pneumoniae (47

1. Mobulid rays are medium- to large-sized pelagic-dwelling planktivorous elasmobranchs that are circumglobally distributed. Brazil has a high diversity of Mobula species, with five of the nine globally valid species and one additional putative new species. 2. Brazil represents a substantial knowledge gap concerning the ecology, distribution and threats to mobulid rays. In global distribution analyses, several species have been underrepresented along the Brazilian coast. 3. The dataset is composed of information from peer-reviewed and grey literature, as well as data from scientific expeditions, citizen science collaboration, social media and local news. 4. We found 6,450 records of manta and devil rays along the Brazilian coast, including Mobula tarapacana, Mobula mobular, Mobula thurstoni, Mobula hypostoma, Mobula birostris and the putative new species (Mobula cf. birostris). 5. Our results revealed alarmingly high captures, such as 4.5 tons of M. hypostoma in a single fishery cruise and 809 individuals of Mobula spp. from a single fleet during one year in the Southeastern region. 6. These findings evidence the fisheries' threats to mobulid species in Brazil and highlight previously unnoted species records, such as the occurrence of M. hypostoma on the entire Brazilian continental shelf, including estuaries and M. tarapacana in coastal regions. 7. Integrative information on the occurrence, distribution, and threats to mobulid rays on local and global scales is crucial to supporting strategies for their effective management and conservation.

The deep ocean is the last natural biodiversity refuge from the reach of human activities. Deepwater sharks and rays are among the most sensitive marine vertebrates to overexploitation. One-third of threatened deepwater sharks are targeted, and half the species targeted for the international liver-oil trade are threatened with extinction. Steep population declines cannot be easily reversed owing to long generation lengths, low recovery potentials, and the near absence of management. Depth and spatial limits to fishing activity could improve conservation when implemented alongside catch regulations, bycatch mitigation, and international trade regulation. Deepwater sharks and rays require immediate trade and fishing regulations to prevent irreversible defaunation and promote recovery of this threatened megafauna group.

The electric rays belonging family Narcinidae are a cosmopolitan group, which has come under increasing scrutiny in relation to the taxonomic composition of the family and its phylogenetic position within the order Torpediniformes. Phylogeographic inferences can provide important insights into the present-day distribution of the narcinid species, as well as the systematics of the group. In this context, the present study evaluates the evolutionary and biogeographic history of the family Narcinidae, inferring distribution patterns and the molecular systematics of these organisms based on the DNA barcode. The results of the analysis indicate that the electric rays originated in the Central Indo-Pacific realm, with all other dispersal events beginning from this region. Two different dispersal routes were observed for the American narcinids. The first route was from the Central Indo-Pacific realm to the Pacific Ocean and then the Caribbean Sea, prior to the closure of the Isthmus of Panama. The second route start on Central Indo-Pacific realm passed South Africa continent before crossing the Atlantic. The principal torpediniform lineages diversified between the end of the Cretaceous and the early Paleocene, with the present-day narcinid taxa arising and diversifying between 25 and 20 Mya. The present study confirms the lack of monophyly in the Narcinidae, validates the genus Narcinops, and restricts the occurrence of the genus Narcine to the coastal environments of the Americas, which emphasizes the need for the review and revalidation of the synonym Syrraxis for the narcinids of the Central/Western Indo-Pacific realm. This study also describes additional lineages for Narcine entemedor and Narcine maculata and validates the occurrence of three species (Narcinesp., Narcine brasiliensis, and Narcine bancroftii) in the Atlantic Ocean, based on the published data, and emphasizes the need for a definitive description of Narcine sp. ### Competing Interest Statement The authors have declared no competing interest.

Preliminary findings regarding the reproduction of three neotropical freshwater stingray species, Potamotrygon henlei, P. motoro, and P. orbignyi, are presented herein. These species are characterized by the presence of a singular functional left ovary and two operational uteri. Two distinct fertility models have been identified: fecundity dependent, and fecundity independent of maternal size. Furthermore, this study briefly outlines the process of capture-induced parturition and its implications for the fate of the litter. Additionally, it sheds light on novel embryonic behavioral patterns, particularly highlighting the active swimming exhibited by embryos within the uterine environment, notably during the latter stages of development. Consequently, it is suggested that these movements, coupled with oral activities and active biting, facilitate branchial ventilation and potentially intrauterine foraging - a phenomenon previously documented only in sharks belonging to the order Lamniformes. Keywords: Abortion, Histotroph, Capture stress, Embryonic nutrition.

Length-weight relationships are valuable in fisheries biology for estimating a fish's average weight at a given length, aiding in predicting population conditions based on total biomass. This study presents length-weight relationships for six threatened shark species captured off the Brazilian Amazon Coast. The specimens of Carcharhinus porosus, Carcharhinus oxyrhynchus, Rhizoprionodon porosus, Sphyrna lewini, Sphyrna mokarran, and Sphyrna tudes were caught by commercial fleets using gillnets with a mesh size of 95-100mm in three distinct periods: from 1997 to 1999, from 2010 to 2012, and from 2018 to 2019. The values of parameter b ranged between 2.98 and 3.28. Keywords: Fishery biology, artisanal fishery, allometry, elasmobranchs

The cyclopoid family Ergasilidae Burmeister, 1835, is the most common group of parasitic copepods infesting fish in Brazil, and the type-genus Ergasilus von Nordmann, 1832 comprises the highest number of species. During a survey of freshwater fish in Northeast Brazil, a new species of Ergasilus was found on the gills of the Longtail Knifefish Sternopygus macrurus (Bloch & Schneider) (Actinopterygii: Sternopygidae) in the Viana lake system, State of Maranhão. Ergasilus lyraephorus n. sp. can be distinguished from its closest congeners mainly because it has a lyre-shaped ornamentation on the ventral surface of first pedigerous somite, a feature that has never been reported in the family. In addition, the new species differs from closely related congeners by having a maxillule bearing three elements, by the large spinules on the interpodal plates of legs 1, 2 and 3, and by having leg 5 reduced to a single seta of moderate size. The present study is the first report of an ergasilid parasitizing S. macrurus , as well as the first parasitic copepod found on a host belonging to the family Sternopygidae Cope.

Little is known about the ecology and distribution of mobulid rays along Brazil's extensive coastline. Here we report opportunistic sightings of manta rays (Mobula cf. birostris) in the Brazilian Amazon estuaries and the Great Amazon Reef System. These sightings consist of manta ray individuals stranded in tide pools, caught in artisanal fisheries, and footage obtained with a submersible. Future investigations on the spatial, temporal, and environmental drivers of manta rays' distribution on the northern Brazilian coast and the threats posed by fishing gear are warranted.

The Shortfin Mako (Isurus oxyrinchus) is a pelagic species found in tropical and temperate waters worldwide. Despite being listed as Endangered on the International Union for Conservation of Nature (IUCN) Red List of Threatened Species, Shortfin Mako remains one of the most frequently captured species by industrial fleets and raising concerns about population declines. While interactions with oceanic fleets are well-documented, coastal captures of Shortfin Mako are less reported. In this study, we present the first record of a Shortfin Mako in the Brazilian Amazon Coast. The specimen was captured incidentally by artisanal fishers using a bottom longline at an approximate distance of 12 nautical miles from the shore. Given the challenges in sustainable fisheries and conservation along the Brazilian Amazon Coast and Shortfin Mako´s global vulnerability, comprehensive approaches, including co-participatory management are essential for better understanding the importance of the area for the species.

The family Carcharhinidae includes the most typical and recognizable sharks, although its internal classification is the subject of extensive debate. In particular, the type genus, Carcharhinus Blainville, 1816, which is also the most speciose, appears to be paraphyletic in relation to a number of morphologically distinct taxa. Isogomphodon oxyrhynchus (Valenciennes, 1839) (the daggernose shark) is a carcharinid, which is endemic to a limited area of the Western Atlantic between Trinidad and Tobago and the Gulf of Maranhão in northern Brazil, one of the smallest ranges of any New World elasmobranch species. In recent decades, I. oxyrhynchus populations have been decimated by anthropogenic impacts, which has led to the classification of the species as critically endangered by the IUCN. However, there is considerable debate on both the validity of the species (I. oxyrhynchus) and the status of Isogomphodon Gill, 1862 as a distinct entity from the genus Carcharhinus. The present study is based on a molecular assessment of the genetic validity of the I. oxyrhynchus that combines mitochondrial and nuclear markers, which were used to identify the biogeographic events responsible for the emergence and dispersal of the species in northern Brazil. The genetic distance analyses and phylogenetic trees confirmed the paraphyly of the genus Carcharhinus, recovering a clade comprising Carcharhinus+I. oxyrhynchus+Prionace glauca (Linnaeus, 1758). Our results indicate not only that the daggernose shark is actually a member of the genus Carcharhinus, but that it is genetically more closely related to Carcharhinus porosus (Ranzani, 1839) than it is to the other Carcharhinus species analyzed. Given this, I. oxyrhynchus and P. glauca are therefore reclassified and recognized as Carcharhinus oxyrhynchus and Carcharhinus glaucus. The daggernose shark, Carcharhinus oxyrhynchus, diverged from C. porosus during the Miocene, when significant geomorphological processes occurred on the northern coast of South America, in particular in relation to the configuration of the Amazon River. It is closely associated with the area of the Amazon plume, and its distinctive morphological features represent autapomorphic ecological adaptations to this unique habitat and do not reflect systematic distinction from Carcharhinus.

Fish mislabeling is a global issue with far-reaching consequences for both food security and biodiversity conservation. This practice involves the intentional or unintentional misidentification of fish species sold in markets and restaurants, often driven by economic gain or cultural preferences. The mislabeling of threatened fish species further exacerbates the problem. This manuscript focuses on an emerging mislabeling practice in the Brazilian Amazon coast, which impacts a critically endangered elasmobranch species, the Daggernose Shark Isogomphodon oxyrhynchus. More specifically, the mislabeling of the Atlantic Tripletail Lobotes surinamensis as the Acoupa Weakfish Cynoscion acoupa has led to intensified fishing activities and incidental capture of the Daggernose Shark. Traditional enforcement approaches have shown limited effectiveness, and alternative conservation interventions, including participatory management and education programs for artisanal fishers, are needed to address this complex issue.

The bluntnose sixgill shark, Hexanchus griseus, is a widely distributed demersal species found in tropical and temperate waters of the Pacific, Atlantic, and Indian Oceans, inhabiting continental shelves and slopes, islands, and mid-ocean ridges at depths ranging from 200 to 1100 m. In the Southwestern Atlantic, this species has been recorded from northeastern to southern Brazil, Argentina, and Uruguay. Despite this, the known distribution of this species in the Southwestern Atlantic is very patchy and, in some cases, still mostly ignored in the literature, such as in northeastern Brazil. This study, therefore, aimed to report 23 new records of Hexanchus griseus in the Tropical Southwestern Atlantic and highlight the presence of this species off the northeastern Brazilian coast. So far, Hexanchus griseus was officially reported from the Fernando de Noronha Archipelago, Saint Peter and Saint Paul Archipelago, and the state of Ceará along the northeast coast of Brazil. Herein, the known distribution is extended to the continental shelf breaks and upper slopes of other Brazilian states, reinforcing the previously reported occurrence of the species near the Saint Peter and Saint Paul Archipelago.

The diversity of popular names used in fish nomenclature off the Brazilian coast makes it difficult to identify species, and many names have their origins in Indigenous languages, mainly Tupi-Guarani. This study sought to understand and update the list of the most popular names and assess some ethnotaxonomic patterns employed by artisanal fishers from the Brazilian Amazon Coast in naming elasmobranchs. Interviews with 314 fishermen from 17 coastal municipalities were carried out employing a semi-structured form, banners, and photographic records of local elasmobranch species, addressing characteristics applied to species identification. A total of 130 ethnospecies were identified (113 names in Portuguese and 17 of Tupi-Guarani origin) for the identification of 22 and 18 species of sharks and rays, respectively. The highest degree of homonyms occurs interspecifically for the Dasyatidae, Mobulidae, Pristidae, Urotrygonidae, Carcharhinidae, Sphyrnidae and Triakidae families. Sphyrna tiburo and Hypanus guttatus comprised the taxa with the highest diversity of common names. Morphological characteristics such as shape, colors, texture, and size of certain body parts are the ethnotaxonomic patterns most applied in shark and ray identification. We conclude that the use of common names for elasmofauna facilitates communication between fishers and that the scientific approach to this local ecological knowledge is fundamental for the management and sustainability of fisheries in the long term.

The Roughskin Dogfish Centroscymnus owstonii is a poorly known species with eventual records along the Western South Atlantic. Different dermal denticles have been historically reported for juveniles and adults, which presupposes changes from a juvenile denticle type to an adult denticle type during growth. The present study was based on a male neonate 324 mm in total length (TL) captured with crab pots on the northeastern continental slope of Brazil, between 400-450 meters. This was considered a newborn based on its small size, very similar to previously reported large embryo dimensions and close to the expected birth size in literature. Three different dermal denticles were observed, alternating from the rostrum to the branchial slits, where a tricuspidated denticle type extended covering the rest of the posterior portion of the body. Dermal denticle types and distribution suggest that the replacement process of dermal denticles begins before birth or early after birth, undergoing at least three changes until reaching the adult dermal denticle type. These different types may be related to uterine epithelial histotroph absorption or embryo movement within the mucous environment, which would be enhanced by largely spaced denticles. The reported fragmented distribution of this species along the Brazilian coast is probably related to insufficient sampling coverage. (C) 2021 Elsevier B.V. All rights reserved.