Luisa Maria Sarmento-Soares

Rivulid killifishes are among the most threatened components of freshwater biodiversity in the Brazilian Atlantic Forest, yet their biogeographic patterns remain poorly documented. This study provides the first comprehensive biogeographic assessment for rivulids across the Southeastern and Eastern Atlantic basins of Brazil. We compiled distribution records for 54 species, analyzing patterns of endemism, similarity between hydrographic regions, and sampling coverage. Our results reveal patterns of hyper-endemism, with 31 species (57.4%) restricted to single basins and a highly aggregated distribution. Faunal similarity between regions was negligible, indicating strong historical isolation, with only 3.7% of species shared between the Eastern and Southeastern Atlantic basins. Seventeen bioregions were delimited across the study area, with minimal faunal overlap. We identified that 50.0% of basins lack any rivulid records, despite the region having been extensively sampled for more than 150 years (including since the Thayer Expedition of 1865–1866). This study area contains the highest concentration of research institutions in Brazil, suggesting that the absence of records reflects genuine absence rather than a sampling artefact. Based on endemism values, we highlight 16 priority basins for urgent conservation management. These findings reveal that small coastal basins harbor a disproportionately high, imperiled, yet overlooked diversity. We argue that effective conservation of this unique evolutionary heritage requires targeted research in unsampled areas, basin-scale management, and expanded protected area mosaics to incorporate these high-endemism micro-basins. Our results provide the biogeographic foundation for evidence-based strategies to prevent the extinction of these fishes.

The integration of morphological and molecular data for Imparfinis species from Amazonian drainages of the Brazilian Shield revealed the presence of three previously undescribed species, which are formally described herein. These species are readily distinguished from their congeners by characters related to coloration: I. melanopterus, from the middle Araguaia River, has a distinctly darker lower caudal-fin lobe; I. nigropunctatus, from the upper Araguaia River, possesses conspicuous black spots on the body; and I. tessellatus, from the upper Tapajós River, is characterized by dark blocks of chromatophores on the body, forming a variegated color pattern. Additionally, our species-delimitation analysis recovered these three morphotypes as independent genetic lineages, exhibiting high levels of genetic divergence. A discussion of distributional patterns of Imparfinis within the Amazon River basin is provided.

The degradation of urban streams is a critical challenge for cities worldwide, often exacerbated by climate change. In Niterói, Brazil, the Itaipu Lagoon and its tributaries, such as Colibris Stream, face siltation, pollution, and riparian forest loss. This article presents and analyzes a six-year (2019–2025) community-led initiative for urban stream restoration, demonstrating a viable socio-technical model. The intervention, carried out by the organized civil society collective ‘Córregos da Tiririca,’ employed an adapted syntropic agriculture protocol to restore a narrow, degraded riparian strip. The core innovation, however, extends beyond the agroforestry technique to the social architecture that sustained it. The Collective evolved into a permanent community of practice, ensuring long-term stewardship. The experience was systematized into a four-phase replicability framework (Social Foundation; Participatory Diagnosis and Planning; Pilot Implementation and Adaptive Learning; Scaling and Institutionalizing Care). This study argues that the most significant outcome is this integrated model itself, where ecological technique and social process are mutually reinforcing. The results show significant ecological recovery along a 900-m stretch, with the establishment of a stratified forest (>70% canopy cover) and a documented return of biodiversity (194 species recorded via citizen science), all driven by collective action. Therefore, this article serves as a practical replication guide for organized civil society groups, offering a scalable strategy for urban watershed regeneration that reconciles ecological restoration with social mobilization and resilience.

A new species of Poecilia, subgenus Pamphorichthys, is described from the Cachoeirinha River, a tributary of the upper Paraguaçu River basin in the Chapada Diamantina, Bahia, Brazil. Pamphorichthys is diagnosed among the Poecilini by the strongly pigmented gonopodium in mature males and the equally pigmented urogenital region in females. The new species exhibits four diagnostic features defining the Pamphorichthys clade within Poeciliidae. Males display a unique combination of a reticulated body pattern with diffuse vertical bars and a highly modified pelvic fin. The male pelvic fin possesses a subterminal process on the second ray, similar to that found in the limbs of Pamphorichthys, but highly modified. Although it shares the unique pelvic-fin processes of Pamphorichthys, its gonopodium exhibits reduced ornamentation, resembling the condition in P. pertapeh and P. akroa. Its discovery in an isolated drainage within the Chapada Diamantina underscores the notable endemism of the region. However, the species faces an imminent conservation crisis. Its only known habitat has undergone severe degradation in the last few decades. An excessive water withdrawal has collapsed the Utinga River, one of the main tributaries of the upper Paraguaçu River, and anthropogenic degradation can lead to the disappearance of species, even before it becomes known.

Trichogenes corresponds to a basal taxon in family phylogeny, with three species in Atlantic Forest domain. One is Trichogenes claviger, occurring in forested streams in the headwaters of the Itapemirim basin, Espírito Santo. Until now, it was known to occur only at two localities in the Picada Comprida stream, a tributary of the rio Caxixe. The present study used environmental DNA (eDNA metabarcoding) for detection of this threatened with extinction species. Individuals were collected using two methods: dip nets for targeted capture and gillnets for passive sampling and generated barcode references for the species, which enabled the catfish detection through eDNA sampling at three of the ten investigated sites. In addition to the target species of this study, it was possible to detect other fish from the community associated with each sample site. A comparison of the methods for estimating species composition per sampled stream demonstrated that the eDNA metabarcoding approach identified their presence with more sensitivity than traditional collection methods, with fishing gears. The results also provide a better understanding of the spatial distribution dynamics of T. claviger and reinforce its conservation status. Thus, eDNA metabarcoding was demonstrated to be a powerful method for monitoring threatened and rare species.

In light of the growing loss of aquatic biodiversity amid the current freshwater biodiversity crisis, systematic conservation planning is crucial for developing conservation policies to establish new protected areas that effectively address the complexity of freshwater environments. This study aims to identify priority basins for conservation of threatened, near-threatened, and restricted-range endemic freshwater fish species in the Northeastern Mata Atlântica freshwater ecoregion, highlighting irreplaceable and critical locations for conservation and impact mitigation. Through spatial prioritization, three scenarios with distinct conservation features were considered: (a) 35 threatened species, (b) 118 near-threatened and restricted-range species, and (c) all 153 species. A total of 50 and 89 basins were prioritized in the first two scenarios, respectively, and 135 basins in the third scenario, with 36 classified as critical due to environmental stressors, particularly in the Rio Doce basin. Our results suggest that the current protected area network is insufficient for safeguarding most target fish species. This study presents an initial framework for prioritizing areas that can provide a basis for further, more refined assessments and to support conservation policies such as national or regional action plans, protecting basins and species.

The Doce River basin is the largest river system in southeastern Brazil. Over the last century, the Doce River has been undergoing a serious process of degradation, culminating in a huge environmental disaster due to Fundão tailing dam bursting in Mariana (Minas Gerais) and causing severe damage to biodiversity and local human communities. Near its mouth, the Doce River harbors an extensive lake area, with over ninety lakes on coastal lowlands. These lakes are of fluvial origin and connected to each other and to the main Doce River by small tributary streams. In this area, one of the main sources of impact on the fish fauna is the presence of non-native fish species. We compared richness, taxonomic diversity, beta diversity, species composition and proportion of non-native species in lakes and streams, and related these variables to each other and to environmental variables. We used the indicator species index (IndVal) to identify species associated with each type of environment. We used multivariate analyses to test the influence of stream habitat on the fish fauna in streams and Generalized Linear Models (GLMs) to test the influence of distance to lakes on the proportion of non-native species in streams, and the influence of this proportion on total and native fish richness and diversity. The results showed that some non-native species originating from lentic environments have adapted to the lakes and are spread throughout the internal lake system. In streams, there are proportionally fewer non-native fish and their distribution is more fragmented, as some stretches do not provide the conditions for the establishment of some of these species, making them potential refuges for native ichthyofauna. As the streams move away from the lakes, the proportion of non-native species tends to decrease. In streams, the richness and diversity of native species are affected by the proportion of non-native species, but not in lakes. The native vegetation in the landscape showed no potential for reducing the invasion of non-native species. The depth and width of the streams are directly related to the proportion of non-native species within the streams and are structural characteristics that should be considered in strategies for the conservation of the fish fauna.

The Atlantic Forest coastal tablelands is home to a wide diversity of small-sized freshwater fish sharing a biogeographically congruent distributional pattern. The annual killifish Xenurolebias are among these remarkable inhabitants in the riparian wetlands with four species in the area. Xenurolebias pataxo are located between the Jucuruçu and Mucuri rivers, geographically replaced by Xenurolebias myersi at the Riacho Doce and the Rio Itaúnas, and, further south, Xenurolebias cricarensis are in the floodplains of the Rio São Mateus and Xenurolebias izecksohni, living in temporary environments of the Rio Barra Seca, north of the Rio Doce. Due to their restricted habitat in the lowlands, these annual killifish could all be designated as a target species, providing benefits in the conservation of riparian wetlands. However, less is known about their habits and real distribution. Otherwise, the accelerated habitat loss is worrisome. Two of these species are threatened with extinction on Red Lists; one is Near-Threatened; and one is Data-Deficient. After ten years since the last species description, our investigations revealed a fifth species, the first recorded south of Rio Doce. The present contribution aims to characterize the occupied habitat by each species within the temporary environments and present an updated distributional data on these fish. Additionally, a new Xenurolebias is described, the first one recorded south of Rio Doce.

The Atlantic Forest coastal tablelands is home to a wide diversity of small-sized freshwater fish sharing a biogeographically congruent distributional pattern. The annual killifish Xenurolebias are among these remarkable inhabitants in the riparian wetlands with four species in the area. Xenurolebias pataxo between the Jucuruçu and Mucuri rivers, geographically replaced by Xenurolebias myersi at the Riacho Doce and the Rio Itaúnas, and further south Xenurolebias cricarensis in the floodplains of the Rio São Mateus and Xenurolebias izecksohni, living in temporary environments of the Rio Barra Seca, north of the Rio Doce. Due to their restricted habitat at lowlands, these annual killifish could be all signed as target species, providing benefits in the conservation of riparian wetlands. However, less is known about their habits and real distribution. Otherwise, the accelerated habitat loss is worrisome. Two of these species are threatened with extinction on Red Lists; one is Near Threatened and one Data Deficient. After ten years since the last species description, our investigations revealed a fifth species, the first recorded south of Rio Doce. The present contribution aims to highlight the habitat occupied by each species within the temporary environments, and present an updated distributional data on these fishes. Additionally, a new Xenurolebias is described, the first one recorded on south of Rio Doce.

Ambientes de riacho, normalmente negligenciados nos centros urbanos, são canalizados, poluídos ou até esquecidos sob o concreto das cidades. Considerando a importância da mata ciliar para a conservação dos riachos e, consequentemente, o bem-estar da população, além de ser o tema em pauta pouco divulgado, o objetivo deste relato é compartilhar a experiência de uma prática que visou à mobilização de processos para a educação ambiental. Tal prática foi desenvolvida com alunos do ensino médio de uma escola pública estadual, no âmbito do projeto de recuperação vegetal da mata ciliar em um córrego urbano, localizado no município de Niterói/RJ, o córrego dos Colibris. O relato indica que a atividade mediada tornou mais efetiva a educação ambiental nos estudantes, visto que estes puderam compreender a importância da restauração da mata ciliar dos rios que drenam para a lagoa de Itaipu como um caminho à revitalização do sistema lagunar.