Abstract A new species of Corydoras is described from the rio Tefé basin, a tributary of the rio Solimões, Amazonas State, Brazil. The new species can be distinguished from its congeners by having the following features: a conspicuous dark brown or black patch transversally crossing the orbit, forming a mask-like blotch; a large, transversally elongated dark brown or black patch extending from the anterior portion of the dorsal-fin base toward the ventral margin of the trunk, and absence of a distinct color pattern along midline of flank. Considering that the new species exhibits a color pattern similar to that of Corydoras pastazensis, the identity of this species was also analyzed herein. The examination of most type specimens, including holotypes, allowed the clear delimitation of C. pastazensis, as well as the confirmation of the previously proposed synonymy with C. pastazensis orcesi. Additionally, the analysis of the morphology of mouth and barbels within Corydoradinae indicated a new hypothesis of homology of the barbels, as well as the proposition of five new characters related to these structures.

The Neotropical freshwater fish (NFF) fauna constitutes the most diverse continental vertebrate assemblage on Earth, with more than 6,345 species distributed across South America, Central America, and the Greater Antilles. These species display a bewildering array of ecophysiological and behavioral traits, or ecotraits, used to exploit habitat and food resources across geographical, climatic, and seasonal gradients. Despite intensive taxonomic and systematic studies, the literature on ecological preferences and tolerances of NFF species is scattered and incomplete, and we have previously lacked a centralized database. Here we present the first comprehensive dataset of ecotraits for the NFF fauna using published data and expert knowledge from the community of Neotropical ichthyologists. This ecomatrix includes adult modal values for 42 ecotraits scored for all valid NFF species, including body size, four of habitat utilization related to water chemistry, 21 of physical habitat structure, 10 of diet (i.e. trophic guilds), and six other behavioral traits. This ecomatrix is a foundation for future studies on the ecology and conservation of Neotropical aquatic biodiversity.

Abstract In this work, we revisited the taxonomy of Hoplisoma paleatum, a species with one of the most extensive taxonomic histories within the genus Hoplisoma. The analysis of the type-specimens of H. microcephalus and non-type specimens from Tres Arroyos, Argentina, led us to propose this species as a junior synonym of H. paleatum. Additionally, considering that the monophyly of Hoplisoma and generic placement of H. paleatum and its closest relatives were recently contested, a broad discussion on the systematics of the genus is provided herein. Considering the potential taxonomic instability related to the recent proposal of Urkumayu, and in light of the large dataset supporting a monophyletic Hoplisoma, we herein consider Urkumayu to represent a junior synonym of Hoplisoma, pending further analysis. A discussion on the taxonomic status of the species in Urkumayu, H. steindachneri and H. osvaldoi is also provided.

Brazil hosts the highest fish diversity globally, underscoring the critical role of Brazilian Scientific Fish Collections (BSFCs) in biodiversity research and conservation. Despite their importance, BSFCs face persistent challenges. This study introduces the CARDUME network, the first nationwide initiative to assess BSFCs and propose strategies to enhance their role in ichthyology. Data from 74 collections across 25 Brazilian federal units reveal that most are affiliated with public universities and house 8 502 992 catalogued specimens in 906 890 lots, including over 2600 primary types. Although digitization efforts are underway in 92% of BSFCs, only 37% currently share data online. Genetic resources are severely limited, with tissue samples available for just 3% of specimens. Significant funding disparities exist, with 70% of collections receiving less than USD170 annually. Gender inequality is also notable, with more male-curated than female-curated collections. Survey responses highlighted issues such as staff shortages, inadequate facilities, and limited resources for fieldwork and collection curation. CARDUME aims to address these gaps through collaboration, professional training, improvement of data quality, and increase of shared data, while also advocating for recognition by Brazilian institutions, funding agencies, and the government. O resumo em portugu & ecirc;s est & aacute; dispon & iacute;vel no material suplementar.

Stellifer naso is known from the State of Bahia (Brazil), but there is a lack of an accurate definition of its type locality. Thayer's expedition (around 1865-1866), led by Louis Agassiz and staff from the Museum of Comparative Zoology (MCZ, Harvard University), intended to explore Brazilian fauna and flora, with most of its material housed in the MCZ and used to describe several species, including S. naso. Examination of specimens from the original description of that species, housed in the MCZ and the Smithsonian National Museum of Natural History, helped review the accurate point of origin for such specimens. A combination of data from reproductive biology and the history of the region further support the actual type locality of S. naso as Iguape Bay, with an error radius of 2.5 km. Damming in the Paragua & ccedil;u River in the early 1980s might have had an impact on the morphological variation over time recorded to this species.

In the present study, we used DNA sequences from three mitochondrial (COI, Cytb, and nd2) and one nuclear (RAG2) marker, to perform species delimitation analyses (ABGD, GMYC, BPP, and bPTP) within Sturisoma to test the validity of currently recognized and potential new species for the genus. Additionally, a historical biogeographic analysis was carried out to test the age and centers of origin for species of the genus. Results found here indicate a high degree of genetic divergence with overlapping morphological characteristics suggesting a greater diversity than previously proposed for the genus. All valid species currently included in Sturisoma were confirmed here, and one potentially undescribed species was recovered. Based on genetic distances, geographical patterns and historical biogeography, the diversification of the group could be related to dispersal events from Western to Eastern Amazonia resulting in sympatric species that are highly divergent genetically but conservative morphologically. The lower (eastern) Amazonas and the Orinoco River basins were identified as the main centers of origin for the genus, with an approximate age of origin of 13 Mya, during the Miocene. The diversity of the genus is likely to be even higher because the Amazon River is a hotspot of hidden biodiversity.

A taxonomic revision of Sturisoma is presented. Individuals including both type and non-type specimens of all valid species were examined. Sturisoma was found to comprise 10 valid species: Sturisoma barbatum, Sturisoma brevirostre, Sturisoma graffini, Sturisoma guentheri, Sturisoma lyra, Sturisoma monopelte, Sturisoma nigrirostrum, Sturisoma reisi, Sturisoma rostratum, and Sturisoma tenuirostre. Furthermore, four new species are described: Sturisoma ghazziae, new species, from the Araguaia River, belonging to the Tocantins-Araguaia basin, Central Brazil; Sturisoma careirensia, new species, from the middle Amazon basin, Brazil; Sturisoma rapppydanielae, new species, from the Purus River, Amazon basin, Brazil; and Sturisoma defranciscoi, new species, from the Putumayo and Solimoes rivers, upper Amazon basin, Colombia, and Brazil. Sturisoma robustum is confirmed as synonym of S. barbatum, species registered along the Paraguay/Parana/La Plata River basin in Argentina, Brazil, and Paraguay. New records were found for S. nigrirostrum as present in the upper Amazon basin, in the Yavari River, Brazil, in addition to its already known locality, the Ucayali River, Peru. The distribution of the type species of the genus S. rostratum is limited to the lower portion of the Amazon basin in the Araguaia, Maranhao, Mearim, Tapajos, and Tocantins rivers and its affluents, Brazil, in contrast to the assumed widespread distribution across the main basins of South America, as previously proposed for the species; the Mearim River is a new record for the species. Updated diagnoses and descriptions are offered for species of Sturisoma, in addition to distribution maps and an identification key for the species.

The family Callichthyidae, which comprises the subfamilies Corydoradinae and Callichthyinae, represents one of the largest families within the Siluriformes. Corydoradinae, the largest subfamily of Callichthyidae, alone accounts for >200 valid species, with new species being described frequently. This subfamily holds significant popularity among catfish enthusiasts worldwide, mainly because Corydoras are small, peaceful, and colourful fishes. Recognizing the existence of polyphyletic groups within Corydoradinae, the aim of this study was to construct a new phylogenetic hypothesis using genomic data (ultraconserved elements) and to re-evaluate the synonymized genera using the most recent morphological data. Our results supported the monophyly of Corydoradinae and identified seven distinct groups of species, each one with an associated pre-available generic name. These genera, namely Corydoras, Aspidoras, Scleromystax, Gastrodermus (resurrected), Osteogaster (resurrected), Brochis (resurrected), and Hoplisoma (resurrected), were all validated based on evidence derived from molecular and morphological analyses. A taxonomic key for the Corydoradinae genera is provided.

Siluriformes are considered as primarily freshwater and have frequently been a model for the study of historical biogeography. Among catfishes, the most diverse clade is the Loricarioidei, a Neotropical group for which the fossil record extends back to the Palaeocene of Argentina. Here we describe a fossil from the early Late Cretaceous of Morocco, exhibiting typical morphological traits of the Loricariidae. A phylogenetic analysis integrating morphological characters with a multigene database for the main loricarioid lineages and outgroups highly supports inclusion of the fossil within the Loricariidae. A time-calibrated analysis corroborates the origin of loricarioids at about 112 MYA. The presence of this loricariid in Africa provides evidence that loricarioids have diversified before the separation of Africa and South America. The Moroccan loricariid shows an ancient evolutionary history that, in Africa, ended in the Late Cretaceous but persisted in South America, later surviving the K/Pg extinction.

The region between the Brazilian Shield and the Atlantic Ocean is characterized by the presence of numerous hydrographic basins isolated by mountainous terrain that flow directly into the ocean without forming wide coastal plains. However, knowledge about the diversity and distribution of freshwater fish in several coastal areas is still incipient. One of these areas is the Costa Verde Fluminense region, situated between the municipalities of Mangaratiba and Paraty in the Brazilian State of Rio de Janeiro. In order to eliminate the gap of knowledge about the freshwater fish fauna of this region, we prepared a list of the species, and dichotomous identification keys and illustrations of all species. We examined material from expeditions carried out between 1942 and 2019, deposited in the Ichthyological Collection of the Museu Nacional, Universidade Federal do Rio de Janeiro, Brazil. The material comes from 29 continental coastal rivers and four drainages on Ilha Grande island. We recognized 54 fish species belonging to 16 families and 9 orders. The order Siluriformes was the most diverse with 18 species, followed by Characiformes with 14 species, Cyprinodontiformes with 10 species, Cichliformes with four species, Gobiiformes with three species, Syngnathiformes with two species, and Gymnotiformes, Salmoniformes and Synbranchiformes with one species each. These records include two putative undescribed species and four introduced species. Phalloceros anisophallos was the most widely distributed species, recorded in 24 drainages. More than a half (52 %) of the native species occur exclusively in coastal streams, demonstrating the importance of the area for biogeographic and conservation studies.

Abstract A new species of stick-catfish Farlowella is described from streams of the lower rio Tapajós drainage, in Pará State, northern Brazil. The new species is distinguished from all congeners by a naked gular region (vs. gular region with plates) and from most congeners by the presence of five lateral series of plate rows on anterior region of body (vs. four). The new species shows variation in the series of abdominal plates and a discussion on the variation of abdominal plates within Farlowella is made and comments on synapomorphic characters in Farlowellini.

Abstract A new species of Loricaria is described from the upper Amazon River basin, Colombia. The new species is distinguished from its congeners primarily by having the dorsal portion of head with uniform black or dark brown coloration extending to three or four plates posterior to dorsal fin base, or with two longitudinal bands from tip of the snout to origin of dorsal fin; abdominal plates tightly joined and completely covering the median abdominal space and pectoral girdle; and pectoral and dorsal fins totally black or dark brown, without bands, spots, or blotches. The new species is further distinguished by plate counts, and body measurements. An analysis of genetic distances using the cytochrome oxidase c subunit 1 marker of the mitochondrial genome showed a clear differentiation between the new species and Loricaria cataphracta (5.8–7.6%), L. nickeriensis (5.7–6.1%), and L. simillima (2.7–7.0%). Species delimitation analyses were carried out, which further supported the new species as a divergent lineage within the genus. Fish species diversity of the upper Amazon River basin and taxonomic issues related to L. simillima are included as part of the discussion.

A new loricariin species of Sturisoma is described from the Cautário, Guaporé, Mamoré, Machado and Soteiro rivers, Madeira River basin, in Bolivia and Brazil. The new species is distinguished from its congeners by the presence of a middorsal longitudinal, thin dark brown stripe on the caudal peduncle, extending from two or three plates posterior to the dorsal-fin base, reaching the origin of the caudal fin, or one or two plates anterior to the origin of the caudal fin; small squarish anteriormost abdominal plates; and a middorsal longitudinal dark-brown stripe from first predorsal plate to near the dorsal-fin origin. Furthermore, the new species is diagnosed from congeners by plate morphology, counts on the median series, coalescent plates and ventrolateral thoracic plates, in addition to measurements related to body and head structures. An analysis of genetic distances using cytochrome C oxidase subunit 1 gene marker of the mitochondrial genome between the new species and several congeners is presented, in addition to a likelihood analysis to illustrate the position of the new taxon within Sturisoma. An identification key for species of the genus currently recorded at the upper Amazonas River basin is provided.

Abstract Aspidoras comprises 25 species currently considered as valid, being widely distributed in Brazil, occurring from the upper rio Paraná basin in São Paulo to coastal basins of Ceará. After Nijssen, Isbrücker’s review more than 40 years ago, no extensive work regarding the taxonomy of Aspidoras was conducted. Our paper presents a comprehensive taxonomic revision of the genus, based primarily on the extensive material that has been collected since then. Considering the new diagnosis plus the available phylogenetic data, A. pauciradiatus and A. virgulatus are transferred to Corydoras and Scleromystax, respectively. New synonymies are proposed: A. eurycephalus and A. taurus with A. albater; A. menezesi and A. spilotus with A. raimundi; and A. microgalaeus and A. marianae with A. poecilus. Additionally, a new species from the Araguaia and Paraguay river basins is described, which can be distinguished from its congeners by the morphology of its complex vertebra and infraorbital 1. Thereby, the number of valid species within Aspidoras was reduced from 25 to 18. Redescriptions for A. albater, A. belenos, A. depinnai, A. fuscoguttatus, A. lakoi, A. maculosus, A. poecilus, A. psammatides, A. raimundi, and A. velites are provided. An identification key to the species of Aspidoras is also provided.

Abstract An expedition crowdfunded by aquarists to a region of the Brazilian state of Pará drained by the Tapajós and Xingu river basins resulted in the capture of five species of Corydoras from the rio Jamanxim basin, a tributary to the rio Tapajós, of which three could be confirmed as new and described herein. The new species can be promptly diagnosed from their congeners by the combination of features related to color pattern and osteology. Considering the gathered information on color patterns and morphology plus field observations, the new species are considered to compose two distinct Müllerian mimicry rings, with two of them forming a mimetic pair, while the third one forms a pair with a fourth non-identified species captured in the same expedition. An identification key to the species of Corydoras from the rio Tapajós basin is also provided.

Abstract A new Ancistrus species is described from Tapajós and Xingu river basins. It is distinguished from its congeners by the singular body color pattern, consisting of dark vermiculated stripes almost all over the body, and also by combination of features as a narrow head, large internostril distance, and absence of rows of enlarged odontodes on the lateral plates. In addition, the new species is distinguished from congeners that inhabit the rio Tapajós basin by the presence of a fully-developed adipose fin (vs. adipose fin absent in Ancistrus parecis and A. tombador, and vestigial adipose fin or absent in A. krenakarore). It differs from A. ranunculus, also from the rio Xingu, by the color pattern, smaller body size, smaller gill opening, and narrower cleithral width. The new taxon adds a new record to the list of species shared among the Xingu and Tapajós basins.

Knowledge about the taxonomy and fish composition from the upper rio Paraúna (rio São Francisco basin) and upper rio Santo Antônio (rio Doce basin) in the middle portion of the Southern Espinhaço mountain range, state of Minas Gerais, Brazil is still incipient. Only few studies focusing on ichthyofaunistic diagnostic and species descriptions in the lower stretches of the rio Santo Antônio are available. Herein the aim was to provide a species list of the freshwater ichthyofauna from the headwaters of both basins in such region, and to verify the occurrence of threatened, exotic, and potentially new species. Sixty species were registered, with 34 associated to the upper rio Paraúna, and 40 to the upper rio Santo Antônio. Two species are included in some threatened category, three are exotics, and 14 represent potentially new species. An identification key of the fish species recorded in the area is also provided.

A new long-snouted Corydoras species is described from two tributaries of the rio Manuripe and a tributary of the rio Madre de Dios, rio Madeira basin, Peru. Corydoras fulleri can be distinguished from its congeners by having the following features: (a) branch of the temporal sensory canal at sphenotic, which gives rise to the supraorbital canal, with two pores; (b) upper tooth plate of branchial arch with three series of teeth; (c) area at the corner of the mouth, ventral to the maxillary barbel, with a small fleshy flap; (d) two moderate-sized dark-brown or black blotches on caudal-fin base, one on its lateral portion and another one on its dorsal portion, blotches variably diffuse and/or fused with each other; (e) absence of a dark-brown or black stripe transversally crossing the orbit; (f) a longitudinal dark-brown or black stripe on the postdorsal region of flank midline, variably fused with the lateral peduncular blotch, some specimens with slender, longitudinally elongated, dark-brown or black blotch on flank midline, forming a dash-like marking, stripe or dash-like blotch diffuse in some specimens; and (g) region around dorsal-fin origin generally lacking dark brown or black blotch, or displaying diffuse blotch.