Araguaia Research Articles

Reevaluation of Rhipidomys emiliae (J.A. Allen 1916) and description of a new Rhipidomys (Rodentia: Cricetidae) species from Amazonia and Cerrado.

We present the revalidation of the sigmodontinae rodent species R. emiliae, as well as the description of a new species for the genus Rhipidomys. The maximum likelihood analysis recovers R. emiliae as sister species of the clade with Rhipidomys sp. nov. and R. ipukensis, with high bootstrap values. Comparisons between these species based on the external, cranial, and dental morphology identified several unique characters in Rhipidomys sp. nov., including more grayish brown color of the dorsal coat, subsquamosal fenestra wide and long, angular process ends in the same position of the end of condyloid process, conspicuous protostyle and enterostyle. We describe a new karyotype (2n = 44 and FN = 64) for the genus and, based on an integrative analysis together with morphology and molecular phylogeny, assign it to R. emiliae, and assign the karyotype with 2n = 44 and FN = 52 to Rhipidomys sp. nov.. The analysis integrating data indicated that R. emiliae has a geographic distribution restricted to the lowlands of eastern Amazonia, whereas Rhipidomys sp. nov. occurs in the central Amazonia and Cerrado. The data showed that some Rhipidomys species have its distribution currently limited by rivers, as Rhipidomys sp. nov. occurring west of the Araguaia-Tocantins interfluve, R. emiliae east of the Tocantins River, and R. ipukensis between the Tocantins and Araguaia rivers. This work, in addition to revealing a still unknown biodiversity describing a species, brings a new understanding to the genus, and shows how integrating different markers helps in the correct association between the nominal form and the karyotype.

New record of Spot-Legged Turtle, Rhinoclemmys punctularia (Daudin, 1801) (Reptilia, Testudines, Geoemydidae), from an Amazon ecotonal zone in the Tocantins–Araguaia river basin, Brazil

We report a new record of Rhinoclemmys punctularia (Daudin, 1801), extending the geographic dis-tribution of this species by 450 km towards the south to the Araguaia River in the state of Pará, Brazil. The new record comes from an ecotonal area of the Cerrado and Amazon biomes, which indicates a possible adaptability of this species in fragmented environments and in agricultural areas. These new findings help enable future investi-gations better understand the distribution of R. punctularia in the southern Amazon Basin and in ecotones.

On a new genus and four new species of the subfamily Cyprettinae (Crustacea, Ostracoda) from Brazilian floodplains.

We describe the new genus Triangocypretta gen. nov. and four new species from Brazilian floodplains. Triangocypretta angustus gen. et spec. nov. and Triangocypretta labiata gen. et spec. nov. were described from the Amazon floodplain only, while Triangocypretta nates gen. et spec. nov. was described from Amazon, Araguaia, and Paran River floodplains. Triangocypretta hirsuta gen. et spec. nov. was recorded from all four floodplains: Amazon, Araguaia, Pantanal and Paran. The new genus is characterized by the triangular shape of the carapace in lateral view, the absence of teeth on the posteroventral inner list in the right valve and the presence of anterior marginal septa in both valves, as well as by the relatively short and thin and -setae on the mandibular palp. All populations found were asexual. Owing to the clear differences in valve anatomy and limb chaetotaxy as compared to species of Cypretta s.s., the four species were allocated to a new genus in the subfamily Cyprettinae.

Are scattered microsatellites weak chromosomal markers? Guided mapping reveals new insights into Trachelyopterus (Siluriformes: Auchenipteridae) diversity.

The scattered distribution pattern of microsatellites is a challenging problem in fish cytogenetics. This type of array hinders the identification of useful patterns and the comparison between species, often resulting in over-limited interpretations that only label it as "scattered" or "widely distributed". However, several studies have shown that the distribution pattern of microsatellites is non-random. Thus, here we tested whether a scattered microsatellite could have distinct distribution patterns on homeologous chromosomes of closely related species. The clustered sites of 18S and 5S rDNA, U2 snRNA and H3/H4 histone genes were used as a guide to compare the (GATA)n microsatellite distribution pattern on the homeologous chromosomes of six Trachelyopterus species: T. coriaceus and Trachelyopterus aff. galeatus from the Araguaia River basin; T. striatulus, T. galeatus and T. porosus from the Amazonas River basin; and Trachelyopterus aff. coriaceus from the Paraguay River basin. Most species had similar patterns of the (GATA)n microsatellite in the histone genes and 5S rDNA carriers. However, we have found a chromosomal polymorphism of the (GATA)n sequence in the 18S rDNA carriers of Trachelyopterus galeatus, which is in Hard-Weinberg equilibrium and possibly originated through amplification events; and a chromosome polymorphism in Trachelyopterus aff. galeatus, which combined with an inversion polymorphism of the U2 snRNA in the same chromosome pair resulted in six possible cytotypes, which are in Hardy-Weinberg disequilibrium. Therefore, comparing the distribution pattern on homeologous chromosomes across the species, using gene clusters as a guide to identify it, seems to be an effective way to further the analysis of scattered microsatellites in fish cytogenetics.

Occurrence of Hyphessobrycon langeanii Lima & Moreira, 2003 (Characiformes, Characidae) in the upper Paraguay river basin

Hyphessobrycon langeanii was originally described as endemic to the upper Araguaia river basin, Brazil. However, our analysis of several Hyphessobrycon specimens collected in the Correntes river basin and another tributary of the Itiquira River in Mato Grosso state (both belonging to the Paraguay river basin) reveals the first verified record of H. langeanii from this basin and from the states of Mato Grosso do Sul and Mato Grosso. The objective of this study is to provide a novel record of H. langeanii from the basin of the Paraguay River and from the state of Mato Grosso do Sul. We compare the newly discovered populations with the populations in the Araguaia river basin, and we also provide a brief discussion on the biogeography of this species.

Agricultural input modifies trophic niche and basal energy source of a top predator across human-modified landscapes

Land-use conversion and resulting habitat fragmentation can affect the source(s) of primary productivity that fuels food webs and alter their structure in ways that leads to biodiversity loss. We investigated the effects of landscape modification on food webs in the Araguaia River floodplain in central Brazil using the top predator, and indicator species Caiman crocodilus (Crocodilia, Alligatoridae). We measured carbon (δ13C) and nitrogen (δ15N) isotope values of three tissues with different isotopic incorporation rates to evaluate spatial and temporal changes in caiman isotopic niche width with hierarchical Bayesian models that accounted for habitat use, intraspecific trait variation (sex and body size), and landscape attributes (composition and configuration). We also measured δ13C values of essential amino acids to assess if different primary producers are fueling aquatic food webs in natural and anthropogenic areas. Spatial analysis showed that caiman in agricultural areas had larger isotopic niche widths, which likely reflects some use of terrestrial resources in environments dominated by C4 plants. Patterns in δ13C values among essential amino acids were clearly different between natural and anthropogenic habitats. Overall, our findings suggest that caimans can persist in heterogeneous landscapes fueled by natural and agricultural energy sources of energy, which has implications for effectively managing such landscapes to maximize biodiversity.

Soil mineralogy and K reserves in soils from the Araguaia River valley, Brazil

In humid tropical regions, intense weathering extensively depletes soil nutrients. However, soils in the Araguaia River Valley, Brazil, are not responsive to potassium (K) fertilization. To explore the reasons for this lack of responsiveness, an extensive exploratory soil sampling campaign was performed in areas of the valley with different land uses and soil management practices. Soil was sampled at depths of 0–20 cm and 20–40 cm, and exchangeable K (Ke) and non-exchangeable K (Kne) were assessed. The average soil Ke content in the region was 66.3 mg kg−1, above the minimum required value for crop growth. The soil Kne content ranged from one to five times the soil Ke content and was greater in the 20- to 40-cm layer than in the 0- to 20-cm layer. The linear correlation between Ke and Kne was significant only in the silt fraction. Mineralogical analysis of the clay and silt fractions of selected samples showed that the dominant minerals in the clay fraction were kaolinite, vermiculite with or without interlayer hydroxy-Al (HIV), illite, goethite, and gibbsite. Mica and feldspar were found in the silt fraction of several samples. In the silt and clay fractions, the main source of Kne was 2:1 phyllosilicates, which may be interstratifications of illite/vermiculite-hydroxy and illite/vermiculite. The results indicated that Urochloa spp. functions as a K scavenger in deep layers and promotes K biocycling in the system. An equation for predicting Kne extracted with nitric acid on the basis of soil Ke and silt contents was developed.

Diversity of eukaryotic and prokaryotic microbiota revealed by metabarcoding in Neotropical floodplain lakes.

The diversity of eukaryotic and prokaryotic communities has been assessed by morphological and genetic approaches, which are used to characterize the microbiota in different environments. Here, planktonic prokaryotic and eukaryotic communities of the Araguaia River, located in the Central region of Brazil, were analyzed based on metabarcoding analysis of rRNA genes to evaluate the diversity of these groups in tropical floodplain lakes. Also, we tested their spatial concordance throughout the Araguaia river. Water samples were collected from 8 floodplain lakes in Araguaia River. The 16S and 18S rRNA genes were amplified and sequenced using Illumina MiSeq. For eukaryotes, 34,242 merged reads were obtained and 225 distinct OTUs were delineated, of which 106 OTUs were taxonomically classified. For prokaryotes, 26,426 sequences were obtained and 351 OTUs were detected. Of them, 231 were classified in at least one taxonomic category. The most representative eukaryotes belonged to Ciliophora, Chlorophyta and Charophyta. The prokaryotic phylum with the most OTUs classified were Proteobacteria, Actinobacteria and Bacteroidetes. The lakes did not show spatial concordance when comparing the similarity between their microbiota. The knowledge of freshwater biodiversity using DNA sequencing for important rivers, such as Araguaia River, can improve microbiota inventories of tropical biodiversity hotspots.

DNA Barcoding of Pyrrhulina australis (Characiformes: Lebiasinidae) reveals unexpected cryptic diversity in the group

Abstract The family Lebiasinidae includes a number of miniature and medium-sized fish species that are endemic to the Neotropical region. Pyrrhulina is the second most speciose lebiasinid genus and it is also the one with the most taxonomic uncertainties. In this context, the present study focused on the Pyrrhulina morphospecies found in a number of different drainage basins in South America to test the alternative proposals on the arrangement of the taxonomic units found within what is assumed to be a single nominal species, Pyrrhulina australis, based on a DNA Barcoding approach. The results of the analyses indicate that Pyrrhulina australis is a species complex, with intraspecific (within-group) genetic distances of up to 3.74%, well above the Optimal Threshold of 1.79% defined in the present study. The species delimitation analyses revealed a surprising level of diversification among the morphospecies evaluated, in particular, in the clade that encompasses Pyrrhulina australis (from the Paraguay River) + P. cf. rachoviana (Lower Paraná River), P. aff. australis I (Araguaia River)/II (Paraguay River)/III (Upper Paraná River)/IV(Guaporé River),and P. marilynae (Teles Pires River), which were arranged in six distinct evolutionary lineages that align with the geographical distribution of the respective drainage basins.

HEMATOLOGY OF Salminus hilarii AND CONSIDERATIONS ON THE POLLUTION OF THE CERRADO RIVERS

In this study, the health and well-being of fish species Salminus hilarii, in a stretch of a headwater river in the Araguaia River basin - Tocantins, Goiás State, were evaluated. Where the objective was to identify and measure the hematological parameters (erythrogram, thrombogram and leukogram of the referred species). The specimens (n = 50) were captured using fishing nets and cast nets. Blood samples were collected by caudal puncture. The hematological data were obtained according to the methodology described in the classic bibliography. Based on the results of the hematological analysis, the relationship between them and their collection area was obtained, as well as the analyzes by microscopy in the search for morphological (genotoxic) alterations, in the micronuclei. Changes or variations in these parameters can be used as indicators of environmental contamination since these animals are inserted in the environment. Thus, the immune responses presented by the analyzed specimens where the difference between the results of these parameters, as well as the presence of genotoxic markers, are indicative of changes in the studied river water quality.

Qualidade da água superficial em comunidades rurais do estado de Goiás durante a estação seca e sua relação com o uso e a ocupação do solo

Abstract Different land uses and occupations can influence water quality and affect the lives of the population, especially of people who live in rural areas. Because rural populations live under conditions of socio-environmental vulnerability, it is necessary to monitor the quality of water resources to prevent diseases. This work aimed to analyze surface water quality in rural and traditional communities in the state of Goiás through the Bascarán Water Quality Index (WQIB) to evaluate the effects of the predominant land use and occupation of each location. Raw water samples were collected from specific points during the dry season. The presence of pesticides was verified through chromatographic analysis, without quantification, and 11 physical-chemical and microbiological parameters were assessed according to standard methods. The results showed that the WQIB ranged in quality from “good” to “pleasant”. Classification as “pleasant” was statistically related to a high incidence of pasture area (> 80%) and classification as “good” with a percentage of agriculture below 30%. The main land uses and occupations were forest, pasture and agriculture. The apparent parameters color, thermotolerant coliforms and dissolved oxygen also indicated contamination of water courses. The detection of pesticides with a high degree of toxicity in the analyzed water resources, mainly in two rivers (the Facada and Sucuapara creeks), put human health at risk in rural areas, even under conditions of small exposure. Carbofuran, banned since 2017, was detected near the Itacaiú community, making it necessary to alert the local government, residents and tourists who use the Araguaia River for different purposes.

Geomorphic diversity of the middle Araguaia River, Brazil: A segment-scale classification to support river management

The complex mosaic of geomorphic units that characterizes the fluvial corridor of large rivers poses challenges to effectively describe and discriminate the landforms diversity, and is relationships with the hydrosedimentological dynamics and state of the system. Consequently, the classification of the diverse array of fluvial features into discrete segments can be a systematic and organized approach useful to sustain geomorphically-informed management strategies. Here we propose a methodological approach and characterize the geomorphic diversity of the middle Araguaia River by applying a classification of reaches into segments with a certain consistent level of morphological variability. A GIS framework developed for this purpose relied on the survey, analysis, and statistical treatment of morphological variables derived from remote sensing data. It allowed to differentiate 19 distinct reaches (R1-R19) that were further clustered into five major segments (SI-SV). We investigated the first-order controls of the fluvial style in each of the identified segments and found that changes in valley gradient influence in a major way the segments I, III, and IV, while the entrance of important tributaries and the nature of the valley floor are natural governing factors in segments II and V, respectively. The system exhibits a significant morphological diversity among segments, and it is strongly influenced by the late Holocene avulsion history of the river. Given the increasing pressure of human activities on the hydrological system, the present study can be of use to subsidize sustainable management plans aiming to safeguard the last large free-flowing river of the Cerrado biome, and our methodological proposal is valid for use in other large rivers worldwide.

A New South American Freshwater Turtle of the Genus Mesoclemmys from the Brazilian Amazon (Testudines: Pleurodira: Chelidae)

We describe a new species of small chelid turtle from perennial streams in the Araguaia River subbasin near Serra das Andorinhas State Park, São Geraldo do Araguaia, Pará, Brazil. It is morphologically distinct and the smallest known member of the genus Mesoclemmys, with an average straight-line carapace length (CL) of 144 mm and maximum recorded CL of 170 mm. The species has a moderate head width of approximately 20% of CL. The carapace and dorsal soft parts are blackish, the plastron is light brownish yellow with a blackish brown central plastral figure, and the ventral soft parts are pale yellow. It has the largest femoral scutes of any Mesoclemmys and its plastral contact formula is Intergular > Anal > Humeral > Femoral > Abdominal > Pectoral > Gular. We describe the shell and skull morphology of the new species and performed genetic analysis using mitochondrial DNA (cytochrome c oxidase, subunits I [COI] and 16S) to build a phylogenetic tree for the genus, which placed the new species as sister to M. vanderhaegei.

Landscape features affect caiman body condition in the middle Araguaia River floodplain

AbstractLandscape modifications often undermine habitat suitability for species’ persistence, with initial effects observed through the physiological responses of individuals and populations. However, some landscape features can allow tolerant wildlife species to persist in human‐modified landscapes, but they are still overlooked. Across distinct agricultural landscapes, we assessed landscape features affecting the body condition (estimate through scaled mass index ‐ SMI) of Caiman crocodilus (Crocodylia, Alligatoridae) in human‐modified landscapes of the Araguaia floodplain, central Brazil. We used a spatial Bayesian model averaging approach to determine the effects of landscape attributes, ectoparasites, tail damage and severe body injuries on caiman body condition. We found that caimans had higher SMI in anthropogenic (ditches and artificial ponds) than natural habitats (lakes or rivers). Overall, caiman SMI was negatively associated with wetland cohesion (an aggregation and connectivity metric). Otherwise, landscape composition did not influence caiman SMI. Further, ectoparasites and body injuries did not affect SMI, whereas tail damage negatively affected SMI. Our findings underscore that caiman populations can adapt to artificial wetlands and irrigated rice fields, provided they incorporate natural and semi‐natural habitat patches that enhance environmental heterogeneity, prey availability, and waterbody availability and connectivity.

Rineloricaria quilombola: a new species of whiptail catfish (Siluriformes, Loricariidae, Loricariinae) from upper and middle Tocantins River basin, Brazil

The genus Rineloricaria comprises 69 valid species and has been considered monophyletic by some authors. The taxonomic history of Rineloricaria is quite complex, especially concerning its wide distribution and morphological plasticity that make it difficult to diagnose and describe new species. Even with the great species-richness of the genus and the huge diversity of the system, the Tocantins-Araguaia River basin hosts only three formally described species of Rineloricaria: R. hasemani, R. lanceolata, and R. osvaldoi, the former is known from lower Tocantins River, R. lanceolata widespread along Amazon basin and the last one restricts to the Araguaia River basin. Recent field expeditions and collection examination revealed an undescribed species of the genus from the upper and middle Tocantins River drainage. The new species is diagnosed among its congeners by having a greater number of premaxillary and dentary teeth (both with up to 15 vs. up to 10 in most congeners). From R. hasemani it is also distinguished by having the edge of snout straight in lateral view and absence of filaments on lower lip. It is also diagnosed from R. lanceolata by having wider cleithral width and a quite different color pattern, lacking a hyalin spot on the base of pectoral and pelvic fins; and from R. osvaldoi by having a lower head depth, triangular head in dorsal view, shorter snout length and other features.

Probable causes of hardening of redoximorphic features in Plinthosols of the Araguaia River floodplain, Central region of Brazil

This study aimed to investigate the possible causes or conditions for the greater hardening or more hardened consistency of the plinthic feature, particularly in relation to forms and quantities of iron both in wet and dry conditions, taking into account that variations in the degree of consistency of these features are a phenomenon of great importance in the behavior of the soils of the Araguaia River floodplain, Brazil, due to its wide agricultural use. Soil features were collected at five positions in the profiles, where initial, central, and base plinthic horizons were detected. The separated samples of matrix, mottle, and plinthite were broken by the Instron apparatus and ground into powder. Then, chemical determinations were carried out by X-ray fluorescence (XRF), sulfuric acid attack (H2SO4), citrate-bicarbonate-dithionite (CBD), acid ammonium oxalate, and X-ray diffraction. The greater hardness of the plinthic features of the soils is directly related to the iron content in the oxidized form contained in its fine fraction and iron oxides are the elements responsible for promoting and maintaining the hardening of the features. The presence of the plinthic feature with the adequate hardness requirements was observed in the cases that presented a combination of the following factors: seasonality of the water regime; absolute Fed contents of at least 40.0 g kg−1 associated with a Fed/Fes ratio of at least 0.35; and Fes values equal to or >100 g kg−1 associated with a Fes/Fet ratio of at least 0.70. High Feo/Fed ratios, above 0.07, are indicative of more unstable features and, at the same time, with greater potential for hardening after drying.

Priority areas and integrated actions for the conservation of Amazonian turtle populations historically over-exploited by humans

The definition of priority areas for conservation and integrated management actions are essential for the effective maintenance and recovery of natural populations, especially for species overexploited by humans. Amazonian chelonians are a food resource historically used by people, resulting in the decline of species populations and worsening the risk of local extinctions. In this paper, we establish priority areas and define integrated conservation actions for populations of three Amazonian chelonians most threatened by human consumption in Brazil (Podocnemis expansa, P. unifilis and P. sextuberculata). To do so, we used 15 prioritization criteria (ecological, logistical and socioeconomic) estimated with 30 years monitoring data in 15 areas by the Amazon Chelonian Program (in portugues Projeto Quelonios da Amazonia, PQA). Each criterion presented four levels of priority with scores increasing according to the relevance for conservation of chelonian populations. The sum of the scores obtained in each area of the PQA allowed a ranking and four categories of importance for conservation to be defined. We also analyzed the similarity of scores among areas of the PQA and among the prioritization criteria to evaluate the application of integrated conservation action strategies. The areas of PQA were classified as Extremely Important for Conservation (Rebio Trombetas River, Middle Xingu River, Middle Araguaia River, Upper Guaporé River), Very Highly Important for Conservation (Middle Purus River, Middle Juruá River, Crixás-Açu River Mouth, Sub-middle Tapajós River); Highly Important for Conservation (Sub-Middle Araguaia River, Amazonas River Mouth, Middle Mortes River); and Important for Conservation (Middle Guaporé River, Lower Branco River, Flechal River, Afuá River). The prioritization and similarity analyses can support the development of a national integrated plan of conservation actions to reduce the overexploitation of Amazon chelonian populations, according to the ecological, logistical and socioeconomic needs of each PQA area.

Evaluation of ichthyofauna in lotic and lentic environments in the Araguaia River basin, Cerrado Biome, Brazil

The Araguaia River is an important watercourse located in Central Brazil and well known for its diversity of fish fauna. Differences between landscape and resources in the distinct environments existing in a floodplain can determine the success of a species. This study presents a list of ichthyofauna species found in lentic and lotic environments in the floodplain of the Araguaia River basin, bordering Mato Grosso and Goiás States. We carried out sampling in July 2019, during the dry season, using diverse fish collection strategies, such as waiting nets, trawl, cast net and fishing rods. Were distributed 12 sampling points between lentic and lotic environments and we captured a total of 168 individuals of 42 species, 19 families and six orders. The predominant orders were Characiformes, Siluriformes and Cichliformes, while the families were Serrasalmidae, Characidae, Triportheidae, Curimatidae and Anostomidae. The genera Triportheus, Psectrogaster and Moenkhausia were the most abundant, while Pimelodus was the most dispersed. Results showed greater abundance and diversity in the lentic environment than in the lotic one, with top-of-the-chain species in both. The variance between environments and the presence of species that are endemic, recently described, of undefined taxonomic status, and bioindicators, highlight the importance of conserving and further studying the ichthyofauna in the Araguaia River basin.

Comparative Phylogeography of Birds Across the Tocantins–Araguaia Interfluve Reveals a New Biogeographic Suture in the Amazon Far East

Few phylogeographic studies have focused on understanding the role of the Tocantins–Araguaia Interfluve (TAI) in the diversification of Amazonian biodiversity. Herein we evaluate the phylogeographic relationships of 14 avian lineages present in the TAI and its two neighboring Amazonian Areas of Endemism: the Xingu (XAE) and Belém (BAE). Four alternative scenarios coupling degree of genetic differentiation and area relationships were tested: (1) populations distributed in TAI, BAE, and XAE are not genetically differentiated from each other (assumed as the null hypothesis); (2) populations from TAI are more closely related to those from BAE; (3) populations from TAI are more closely related to those from XAE; and (4) TAI populations represent independent or endemic lineages not present in either the BAE or XAE. Molecular analyses considered Bayesian Inference methods and Bayesian Information Criterion (BIC) evolutionary models, haplotype sharing and genetic differentiation estimates. We found three distinct phylogeographic patterns: (i) four lineages presented no population structure across XAE, TAI and BAE; (ii) six lineages were represented in the TAI with distinct phylogroups replacing each other between XAE and BAE, but with varying degrees of contact and evidence of gene-flow within the TAI; and (iii) for four lineages, the Tocantins River acted as a barrier isolating BAE phylogroups from those inhabiting both TAI and XAE. These different patterns demonstrate a heterogeneous response to the barrier effects posed by both the Tocantins and Araguaia rivers on the local fauna. Historical geomorphological and hydromorphological factors, such as the presence and absence of paleochannels and anastomosed channel stretches and variations in sedimentation rates support a dynamic history for the Araguaia-Tocantins floodplains, likely accounting for the observed heterogeneity in species’ specific responses. Finally, the scenario of phylogeographic breaks and population subdivision recovered herein along the Tocantins and Araguaia rivers, associated with the existence of contact zones and the occurrence of gene flow, define the TAI as hitherto unknown biogeographic suture zone, localized in southeasternmost Amazonia.

Phylogenetic Evidence for the Cyphocharax saladensis Clade with Description of a New Species of Cyphocharax Endemic to the Upper Rio Paraguai Basin (Teleostei: Curimatidae)

New genetic and morphological data support the recognition of a distinct monophyletic group, the Cyphocharax saladensis clade, which includes C. vanderi, C. saladensis, C. boiadeiro, and a new species. This four-species group can be recognized by modifications in the laterosensory system with instances of incomplete or interrupted poring, by the ontogenetic development of the lateral line with larger specimens having a more developed laterosensory system, and by the presence of a patch of dark pigmentation over the caudal peduncle. The new species is described from the upper Rio Correntes, an upland tributary of the upper Rio Paraguai in central Brazil and is diagnosed by the presence of a thin longitudinal black stripe, by the variable shapes of the dark blotches on the caudal peduncle, and by morphometric and meristic data. New mitochondrial data from paratypes provide clear evidence of genetic distinction between the new species and congeners, and additionally place it as the sister species to C. boiadeiro from the upper Rio Araguaia. Based on the updated molecular phylogeny and biogeographic information, we propose an evolutionary hypothesis with four events of river captures with subsequent allopatric speciation of the new species and C. boiadeiro in the Correntes and Araguaia systems. The new species is suggested to be categorized as Near Threatened, living in a strongly impacted region of the Brazilian Cerrado.