Fishes (Actinopterygii) of the rapids and associated environments in the lower Vaupés River Basin: an undiscovered Colombian Amazon diversity.

The Vaupés River stands out as one of the few within the Amazon basin due to its numerous rapids. These riverine fast-flowing sections not only provide habitat to highly specialized fishes but also function as natural barriers hindering the movement of fish along its course. During a fish-collecting expedition in the lower Vaupés River basin in Colombia, 95 species were registered belonging to 30 families and seven orders. Despite recent inventories in the region, our comprehensive sampling efforts particularly focused on the rapids and associated rheophilic fauna, allowing us to contribute the first records of four fish species in Colombia (Mylopluslucienae Andrade, Ota, Bastos & Jégu, 2016, Tometesmakue Jégu, Santos & Jégu, 2002, also first record of the genus, Leptodoraspraelongus (Myers & Weitzman, 1956), and Eigenmanniamatintapereira Peixoto, Dutra & Wosiacki, 2015) and six presumably undescribed species (i.e., Jupiaba sp., Moenkhausia sp., Phenacogaster sp., Bunocephalus sp., Hemiancistrus sp., and Archolaemus sp.). In this study, a commented list of the ichthyofauna of these environments is presented, as well as a photographic catalog of fish species integrated into the CaVFish Project - Colombia.

Macroevolutionary consequences of karyotypic changes in the neotropical Serrasalmidae fishes (Ostariophysi, Characiformes) diversification.

In the Neotropical region, one of the most diverse families of freshwater fishes is the monophyletic Serrasalmidae. Karyotypically, the family shows high diversity in chromosome numbers (2n = 54 to 64). However, little is discussed about whether the chromosomal changes are associated with cladogenetic events within this family. In the present study, we evaluated the role of chromosomal changes in the evolutionary diversification of Serrasalmidae. Our phylogenetic sampling included 36 species and revealed three main clades. The ancestral chromosome number reconstruction revealed the basic number 2n = 54 and a high frequency of ascending dysploid events in the most derived lineages. Our biogeographic reconstruction suggests an Amazonian origin of the family at 48-38 Mya, with independent colonization of other basins between 15 and 8 Mya. We did not find specific chromosomal changes or increased diversification rates correlated with the colonization of a new environment. On the other hand, an increase in the diversification rate was detected involving the genus Serrasalmus and Pygocentrus in the Miocene, correlated with the stasis of 2n = 60. Our data demonstrate that chromosomal rearrangements might have played an important evolutionary role in major cladogenetic events in Serrasalmidae, revealing them as a possible evolutionary driver in their diversification.

Phylogenomics, evolution of trophic traits and divergence times of hemiodontid fishes (Ostariophysi: Characiformes).

The South American characiform family Hemiodontidae comprises five genera and 34 species. The family lacks comprehensive phylogenetic hypotheses resolving its species relationships. The studies that addressed these questions exhibited a narrow taxon sampling or used single-locus markers. Herein we surveyed hundreds of ultraconserved elements (UCEs) loci to provide the first molecular phylogenetic hypothesis and divergence time estimates for hemiodontids encompassing all its genera and most species (27 of the 34 valid species). We also tracked the history of the protractile upper jaw in the genera Argonectes and Bivibranchia across the recovered phylogenies through ancestral state reconstruction. Our results corroborate the monophyly of Hemiodontidae and the genera Argonectes and Bivibranchia in all phylogenetic methods with maximum clade support. The genera Anodus and Hemiodus were not monophyletic because Anodus elongatus was sister to the monotypic Micromischodus instead of A. orinocensis, and H. immaculatus did not form a clade with its other congeners, but instead was sister to the clade including Anodus and Micromischodus. All remaining species of Hemiodus were placed together into a monophyletic group, where they were arranged into four major subclades. The relationship in the family is summarised as: (Bivibranchia, (Argonectes, ((H. immaculatus, (Anodus, Micromischodus)), Hemiodus clade))), in discordance with the morphological phylogeny that placed all genera monophyletic and resolved the family as: ((Anodus, Micromischodus), (Hemiodus, (Argonectes, Bivibranchia))). The origin of Hemiodontidae was estimated from the Late Cretaceous to the Middle Paleogene, with the mean age in the Paleocene, while the origin of most hemiodontid genera except Bivibranchia occurred in the Miocene. Unordered parsimony and likelihood reconstruction indicates that Argonectes and Bivibranchia developed their protractile upper jaw independently.

Small Body, Large Chromosomes: Centric Fusions Shaped the Karyotype of the Amazonian Miniature Fish Nannostomus anduzei (Characiformes, Lebiasinidae).

Miniature refers to species with extraordinarily small adult body size when adult and can be found within all major metazoan groups. It is considered that miniature species have experienced severe alteration of numerous morphological traits during evolution. For a variety of reasons, including severe labor concerns during collecting, chromosomal acquisition, and taxonomic issues, miniature fishes are neglected and understudied. Since some available studies indicate possible relationship between diploid chromosome number (2n) and body size in fishes, we aimed to study one of the smallest Neotropical fish Nannostomus anduzei (Teleostei, Characiformes, Lebiasinidae), using both conventional (Giemsa staining, C-banding) and molecular cytogenetic methods (FISH mapping of rDNAs, microsatellites, and telomeric sequences). Our research revealed that N. anduzei possesses one of the lowest diploid chromosome numbers (2n = 22) among teleost fishes, and its karyotype is entirely composed of large metacentric chromosomes. All chromosomes, except for pair number 11, showed an 18S rDNA signal in the pericentromeric region. 5S rDNA signals were detected in the pericentromeric regions of chromosome pair number 1 and 6, displaying synteny to 18S rDNA signals. Interstitial telomeric sites (ITS) were identified in the centromeric region of pairs 6 and 8, indicating that centric fusions played a significant role in karyotype evolution of studied species. Our study provides further evidence supporting the trend of diploid chromosome number reduction along with miniaturization of adult body size in fishes.

Revealing the Satellite DNA History in Psalidodon and Astyanax Characid Fish by Comparative Satellitomics.

Eukaryotic genomes are usually enriched in repetitive DNA sequences, which can be classified as dispersed or tandemly repeated elements. Satellite DNAs are noncoding monomeric sequences organized in a head-to-tail fashion that are generally located on the subtelomeric and/or pericentromeric heterochromatin. In general, a single species incorporates a diverse group of satellite DNA families, which collection is called satellitome. Here, we characterized three new satellitomes from distinct characid fish (Psalidodon fasciatus, P. bockmanni, and Astyanax lacustris) using a combination of genomic, cytogenetic, and bioinformatic protocols. We also compared our data with the available satellitome of P. paranae. We described 57 satellite DNA (satDNA) families of P. fasciatus (80 variants), 50 of P. bockmanni (77 variants), and 33 of A. lacustris (54 variants). Our analyses demonstrated that several sequences were shared among the analyzed species, while some were restricted to two or three species. In total, we isolated 104 distinctive satDNA families present in the four species, of which 10 were shared among all four. Chromosome mapping revealed that the clustered satDNA was mainly located in the subtelomeric and pericentromeric areas. Although all Psalidodon species demonstrated the same pattern of clusterization of satDNA, the number of clusters per genome was variable, indicating a high dynamism of these sequences. In addition, our results expand the knowledge of the As51 satellite DNA family, revealing that P. bockmanni and P. paranae exhibited an abundant variant of 39 bp, while P. fasciatus showed a variant of 43 bp. The majority of satDNAs in the satellitomes analyzed here presented a common library repetitive sequence in Psalidodon and Astyanax, with abundance variations in each species, as expected for closely related groups. In addition, we concluded that the most abundant satDNA in Psalidodon (As51) passed through a diversification process in this group, resulting in new variants exclusive of Psalidodon.

Distribution and accumulation of major and trace elements in water, sediment, and fishes from protected areas of the Atlantic Rainforest.

Environmental pollution affects the quality of the natural environment where major and trace elements have been commonly found to accumulate in biotic and abiotic matrices. The purposes of this research were (1) to assess the accumulation and distribution of 24 major and trace elements in water, sediments, and muscle and gills of ten native fishes from two natural areas with different degree of protection in the Atlantic Rainforest, (2) to discuss potential origin of the elements related to the land use, and (3) to assess the human health risk for water and muscle fish consumption in general and fisher populations. Major and trace elements were determined by inductively coupled plasma mass spectrometry. Concentrations of Ag, Cu, and Se in water and Cr, Cu, Hg, Mn, Ni, and Zn in sediment were higher than the international guidelines for the aquatic biota protection. Muscle Cr, Cu, Ni, Pb, Hg, and Zn from several species (both studied areas) were above guidelines for human consumption. The bioaccumulation factor (< 6936) was higher in gills than in muscle, and indicated that Andromakhe saguazu, Andromakhe paris, Gymnogeophagus lipokarenos, and Steindachnerina biornata were macroconcentrators of Zn, and Australoheros ykeregua, G. lipokarenos, and Hemiancistrus fuliginosus were macroconcentrators of Se and Sr. The hazard index and target hazard quotient indicated that there is no risk from chronic consumption of water or fish. The results show the need to reduce the entry of pollutants into streams, paying special attention to reducing runoff in deforested areas.

Cannibalism rate and mLeptin expression are influenced by photoperiod and diets in Piracanjuba, Brycon orbignyanus (Valenciennes, 1850) larvae.

Piracanjuba (Brycon orbignyanus) is a species with great productive potential, and during its larval phase, it presents intense cannibal activity. The photoperiod and diet are primary feed behaviour and cannibalism modulators to fishes. This experiment aimed to verify the effect of different photoperiods and diets in Piracanjuba larviculture. Larvae were kept under different photoperiods - 12 h light: 12 h dark (12 L: 12D); 24 h light:00 h dark (24hL: 00D) - Larvae were fed with Artemia nauplii and a formulated micro-diet in a factorial scheme for 10 days, and at the end of the experimental period, the influences of the treatments on performance and quantitative expression of mLeptin and mBmall1 were evaluated. In order to quantify the expression of mLeptin and mBmall1, qPCR adopting ß-actin and Elongation Factor 1 as endogenous genes was used. The primers for all the analysed transcripts were obtained through multiple sequences alignments of different fish species. It was observed that the diet and photoperiod influence the performance of Piracanjuba (B. orbignyanus) larvae in the initial phase of larviculture. Feeding with artemia nauplii and the photoperiod of 24 L:00D reduce cannibalism rates in intensive Piracanjuba larviculture. The results on the rate of cannibalism, rate of survival and the relative expression of mLeptin are related to the survival rate of the larvae, and it is inversely proportional to the cannibalism rate. The expression levels of mBmall1 showed a correlation with the final weight of the larvae. Piracanjuba Larvae under a photoperiod of 24 light and fed Artemia nauplii showed more significant levels of mLeptin expression.

Characterizing the spatial signal of environmental DNA in river systems using a community ecology approach.

Environmental DNA (eDNA) is gaining a growing popularity among scientists but its applicability to biodiversity research and management remains limited in river systems by the lack of knowledge about the spatial extent of the downstream transport of eDNA. Here, we assessed the ability of eDNA inventories to retrieve spatial patterns of fish assemblages along two large and species-rich Neotropical rivers. We first examined overall community variation with distance through the distance decay of similarity and compared this pattern to capture-based samples. We then considered previous knowledge on individual species distributions, and compared it to the eDNA inventories for a set of 53 species. eDNA collected from 28 sites in the Maroni and 25 sites in the Oyapock rivers permitted to retrieve a decline of species similarity with increasing distance between sites. The distance decay of similarity derived from eDNA was similar and even more pronounced than that obtained with capture-based methods (gill-nets). In addition, the species upstream-downstream distribution range derived from eDNA matched to the known distribution of most species. Our results demonstrate that environmental DNA does not represent an integrative measure of biodiversity across the whole upstream river basin but provides a relevant picture of local fish assemblages. Importantly, the spatial signal gathered from eDNA was therefore comparable to that gathered with local capture-based methods, which describes fish fauna over a few hundred metres.

A new species of Cambeva (Siluriformes, Trichomycteridae) from the Rio Iguaçu basin, Paraná State, Brazil and redescription of Cambeva stawiarski (Miranda Ribeiro 1968).

This work aimed to describe Cambeva cauim, sp. nov., endemic to the Rio Iguaçu basin, Brazil and redescribe Cambeva stawiarski using external and internal morphological data through the revision of specimens deposited in fish collections, including the type material. In this process, we have also added comments on the possible type locality of C. stawiarski. C. cauim, sp. nov. and C. stawiarski are mainly diagnosed by the anatomy and number of procurrent caudal-fin rays in addition to colouration and several meristic and morphometric characters. Both species are compared with other possibly related species and their synapomorphic characters are discussed. C. cauim, sp. nov. and C. stawiarski along with eight other congeners are endemic to the Rio Iguaçu basin, a high impacted freshwater region which could be considered as a biodiversity hotspot to the genus.

Sex-Dependent Inheritance of B Chromosomes in Psalidodon paranae (Teleostei, Characiformes) Revealed by Directed Crossings.

B chromosomes are additional dispensable elements to the standard chromosomal set of an organism. In most cases, their transmission differs from Mendelian patterns, leading to their accumulation or extinction. The present study aimed to describe, for the first time, the transmission pattern of B chromosome in a population of Psalidodon paranae through directed crosses, as well as to analyze the populational dynamics of B chromosome. Our results revealed the possible elimination of B chromosome in crossings where only females were B-carriers, with a mean transmission rate (kB) of 0.149; however, kB was significantly higher in crossings involving male B-carriers (kB = 0.328-0.450). Moreover, we observed an increase in the frequency of B chromosomes in the natural population of P. paranae in the last two decades. These apparently contradictory results can make sense if the B chromosome provides adaptive advantages to their carriers. Here, we observed a differential transmission of B chromosomes in each sex of parental individuals, with higher transmission rates in crossing involving males B-carriers, in addition to describe the temporal changes of B chromosome frequency in P. paranae.

Efecto de etilenglicol y leche en polvo en la criopreservación de semen de bocachico Prochilodus magdalenae / Effect of ethylene glycol and milk powder in the cryopreservation of bocachico semen Prochilodus magdalenae

RESUMEN Bocachico Prochilodus magdalenae es una especie endémica y la más importante de la pesquería continental colombiana. No obstante, sus capturas han disminuido aproximadamente el 67% en los últimos cuarenta años, por tanto ha sido categorizada como vulnerable a la extinción. La criopreservación de semen, es una herramienta biotecnológica de conservación por tanto el objetivo del presente estudio fue evaluar la criopreservación de semen de bocachico con etilenglicol (EG) y leche en polvo descremada (LP). La solución crioprotectora estuvo compuesta por EG (6, 8 o 10%), LP (3, 5 o 7%) y glucosa 6%. La calidad del semen descongelado se evaluó con un software tipo CASA (computer assisted semen analysis). El porcentaje de inclusión de EG, no afectó significativamente ninguno de los parámetros de calidad seminal evaluados (p>0,05), a excepción de la tasa de eclosión (p<0,05); mientras que, la LP afectó significativamente el porcentaje de espermatozoides estáticos (p<0,05) y las tasas de fertilización y eclosión (p<0,01). La mayor movilidad total se obtuvo cuando EG se incluyó a 10% y la LP a 7% (38,4±18,4%) (p<0,05); pero las mayores tasas de fertilización (54,3-64,2%) y eclosión (47,7-57,5%) se obtuvieron cuando EG se incluyó a 6 u 8% y la LP se incluyó a la menor concentración evaluada (3%), sin observarse diferencia significativa entre estos tratamientos (p>0,05). Los resultados permiten concluir que la combinación EG 6% con LP 3% permiten la criopreservación de semen de Prochilodus magdalenae de buena calidad y capacidad fecundante.

ABSTRACT Bocachico Prochilodus magdalenae is an endemic species and the most important of the Colombian continental fishery. Its catches have decreased by approximately 67% in the last forty years and, it has been categorized as extinction vulnerable. Semen cryopreservation is a biotechnological conservation tool; therefore, the aim of this study was to evaluate bocachico semen's cryopreservation with ethylene glycol (EG) and skimmed milk powder (LP). The cryoprotective solution was composed of EG (6, 8 or 10%), LP (3, 5 or 7%) and glucose at 6%. The quality of the thawed semen was evaluated with CASA software (computer assisted semen analysis). The inclusion percentage of EG did not significantly affect any of the evaluated semen quality parameters (p>0,05), except for the hatching rate (p <0.05). In contrast, LP presented significant effects on the percentage of static sperm (p <0,05) and on fertilization and hatching rates (p<0,01). The highest total motility was achieved with EG included at 10% and the LP 7% (38,4±18,4%) (p<0,05); but the highest fertility rates (54,3-64,2%) and hatching (47,7-57,5%) were registered when EG included at 6 or 8% and LP included at the lowest rate evaluated (3%), no significant difference was observed between these treatments (p>0,05). The results allow us to conclude that the combination EG 6% with LP 3% allows the cryopreservation of Prochilodus magdalenae semen of good quality and fertilizing capacity.

Ivermectin: A multilevel approach to evaluate effects in Prochilodus lineatus (Valenciennes, 1836) (Characiformes, Prochilodontidae), an inland fishery species.

Ivermectin (IVM) is one of the most widely used antiparasitics worldwide. It is a potent and effective drug for treatment and prevention of internal and external parasitic infections of livestock and humans. IVM is excreted unchanged in manure of treated animals. Thus, residues of IVM may reach aquatic systems, affecting non-target organisms such as fish. Although the presence of IVM in aquatic environments has been reported, a multilevel approach (from cellular to behavioral responses) is necessary to determine the health of exposed organisms and the environmental risks associated. The aim of the present study was to investigate the response of the Neotropical fish Prochilodus lineatus, one of the main target species of South American freshwater fisheries, exposed to environmental concentrations of IVM: low (0.5 µg L-1) and high (1.5 µg L-1). Behavioral responses were assessed in juvenile fish and included water column use, routine swimming, total distance travelled, total activity time and Maximum swimming speed achieved during the escape response. Biochemical/oxidative stress responses assessed included brain acetylcholinesterase (AChE), catalase (CAT) and glutathione S-transferase (GST) activities; total antioxidant competence against peroxyl radicals (ACAP) and lipid oxidative damage (TBARs). Hematological biomarker responses included blood glucose levels, hematocrit, hemoglobin concentration, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, and mean corpuscular volume. Condition factor and hepatosomatic index were also calculated. The lowest IVM concentration caused a significant decrease in GST activity and maximum swimming speed during the escape response. Multivariate analysis with biochemical/stress and behavioral data revealed overall effects of IVM treatments. This multilevel analysis shows detrimental effects related to swimming behavior and predator avoidance which could affect population size and size-structure of P. lineatus. To our knowledge this is the first attempt to assess the effects of IVM on Neotropical fishes using an integrative approach based on biomarkers from different levels of biological organization.

Two new species of Hypostomus suckermouth-armoured catfishes (Teleostei: Loricariidae) from central Brazil.

This study describes two new endemic Hypostomus species from central Brazil, which were previously identified as genetically distinct lineages in a recent genomic study that recommended their testing and potential description based on morphological data. A machine learning classification procedure (random forest) was used to investigate morphological variation and identify putatively diagnostic characters for these candidate species and revealed that each is morphologically distinct. The new species Hypostomus cafuringa is characterized by small size, dark spots under a light background, deeper caudal peduncle and shorter first ray of the pectoral fin and base of the dorsal fin when compared to congeneric species from the region. H. cafuringa is known from the headwaters of the Maranhão River, upper Tocantins River basin, Distrito Federal, Brazil. The second new species, Hypostomus crulsi, is characterized by dark spots under a light background, absence of plates along the abdomen region, shorter first ray of the pelvic fin, shorter first ray of the pectoral fin and smaller body size. H. crulsi is known from the headwaters of the São Bartolomeu River, upper Paraná River basin, Distrito Federal, Brazil. The rapid conversion of natural habitats for agricultural development and the isolation of protected areas represent a serious threat to the continued existence of these two newly described endemic species, which warrant conservation assessment.

The crystalline waters of the Bodoquena Plateau revealed Hypostomus froehlichi (Siluriformes: Loricariidae), a new armored catfish from the rio Paraguay basin in Brazil.

The menaced and poorly-known waters of the Bodoquena Plateau revealed a new resident, the stunning Hypostomus froehlichi sp. n., a large-sized armored catfish, which is finally described after more than twenty years since its discovery. The Bodoquena Plateau is drained by the rio Paraguay basin, and is located in the state of Mato Grosso do Sul, Brazil. The new species differs from its congeners on the Bodoquena crystalline waters by having teeth with morphological and numerical variation in adult specimens. There is a continuous range of specimens having about 20 thick and worn teeth to specimens having about 50 thin teeth with intact crowns and lanceolate main cusps. Additional diagnostic characters are: dentaries angled more than 90 degrees, dark blotches, one plate bordering supraoccipital, moderate keel along dorsal series of plates, usually two rows of blotches per interradial membrane on dorsal, pectoral and ventral fins, and by attaining comparatively large size. Hypostomus froehlichi seems to be endemic to the area of the Bodoquena Plateau, in rivers draining to the rio Miranda. The description of the new species reveals a potential conservation flagship species as it is one of the most seen and documented fish by visitors and divers in the clear waters from the touristic, though menaced, Bonito region in Brazil.

Integrative taxonomy reveals the historically poorly defined armoured catfish Hypostomus variipictus (Ihering 1911), from the upper rio Paraná basin, Brazil (Siluriformes, Loricariidae).

In a recent expedition to the rio Grande basin, a tributary of the rio Paraná in southern Brazil, individuals of the armoured catfish genus Hypostomus with a peculiar and beautiful colour pattern composed of pale vermiculations on the head and four to five horizontal stripes on the flanks were collected. Initially, the specimens were identified as a colour morph of the pale-spotted H. margaritifer. However, when we compared their partial cytochrome C oxidase subunit I (COI) mitochondrial gene to sequences of some typically pale-spotted H. margaritifer, the striped specimens were genetically distinct. Further analysis of the striped individuals revealed that they are the poorly known but valid species Hypostomus variipictus, which was described by Ihering in 1911 from the rio Pardo, a tributary of the rio Grande, upper rio Paraná basin, in São Paulo State, Brazil. Since its descriptions, no robust taxonomic work has been published concerning this species. In this study, the newly sampled population was compared to the original description and to the holotype of H. variipictus, providing the foundation for a complete redescription, proper diagnosis, and first live colour illustration and description of the previously hidden H. variipictus.

When destruction comes first: Two new species of Hypostomus Lacépède, 1803 (Siluriformes: Loricariidae) from a deeply-impacted river in the Rio São Francisco basin in Brazil.

Environmental disasters affecting Brazilian rivers have been frequent recently, especially involving mining activities. Two recent dam-rupture events suddenly released millions of cubic meters of iron tailings downstream into two major Brazilian watersheds. These events generated major losses to the environment and human life. Additionally, the biodiversity in both watersheds was still incompletely known. Two new species of the armoured catfish genus Hypostomus were discovered in the Rio Paraopeba and surrounding rivers of the Rio São Francisco Basin. The species share some main characteristics including a depressed body, large dark spots on a clearer background and the absence of keels on flanks. However, while one species (Hypostomus freirei sp. n.) has a large mandibular ramus and numerous slender teeth, the other (Hypostomus guajupia sp. n.) has a shorter mandibular ramus and few robust teeth. The discovery of these two new mid-sized fish species emphasizes the presumption that the effects of major environmental disasters cannot be fully estimated as local biodiversity is not completely known. This discovery in a recently devastated area also shows that tough environmental laws for the protection, supervision and mitigation of major impacts are urgently needed in developing countries.

Hypostomus hermanni redescription and a new species of Hypostomus (Siluriformes: Loricariidae) from Upper Paraná River basin, Brazil

A redescription of Hypostomus hermanni is presented herein along with the description of a new species of Hypostomus, which is apparently endemic to the Ivaí River basin, a tributary of the Upper Paraná River basin, Brazil. Hypostomus hermanni is diagnosed from congeners mainly by having: usually large black blotches on body and fins; absence of keels on compound pterotic, on pre-dorsal plates, and on lateral series of bony plates; by having parieto-supraoccipital and predorsal region flat; and by having less than 46 teeth per each premaxilla or dentary ramus. The new species is distinguished from congeners9au0 mainly for lacking conspicuous blotches, parieto-supraoccipital non-carinate, and villiform bicuspid teeth.

Uma redescrição de Hypostomus hermanni é aqui apresentada, juntamente com a descrição de uma nova espécie de Hypostomus, que é aparentemente endêmica da bacia do rio Ivaí, afluente do alto rio Paraná, Brasil. Hypostomus hermanni é diagnosticada de suas congêneres principalmente por apresentar: geralmente grandes manchas pretas ao longo do corpo e nadadeiras; ausência de quilhas no pterótico-composto, nas placas pré-dorsais e nas séries laterais de placas ósseas; por ter as regiões do parieto-supraoccipital e predorsal planas; e por ter menos que 46 dentes por cada ramo premaxilar ou dentário. A espécie nova distingue-se de suas congêneres principalmente pela ausência de manchas conspícuas no corpo, e supraocciptal não quilhado e dentes viliformes bicuspidados.(AU)

Streams fish from Upper Araguaia and Middle Rio da Mortes basin, Brazil: generating subsidies for preservation and conservation of this critical natural resource / Peixes de riachos das bacias do alto rio Araguaia e médio Rio das Mortes, Brasil: gerando subsídios para preservação e conservação desse importante recurso natural

The Araguaia River basin has the highest fish biodiversity within the Cerrado biome (Brazilian savannah), with many endemic and threatened species by human activities. Despite growing efforts to catalog Neotropical freshwater fish biodiversity, many regions are still undersampled. Our objective is to complement the information about stream fish in two hydrographic basins in the Cerrado. We sampled 72 streams with 50 m stretch in the Upper Araguaia (n = 32) and Middle Rio das Mortes (n = 40) basins. We collected 14,887 individuals distributed in 137 species, 81 genera, 30 families, and six orders. Characidae, Loricariidae, and Cichlidae were the families richer in species. We found a high diversity of rare fish species in the streams sampled, ca. 71.5% of the species had at least five individuals collected, and 18 species had only one collected specimen. The most frequent species were Astyanax cf. goyacensis, Knodus cf. breviceps, and Characidium cf. zebra. Both basins shared around 43% of the species. We caught 76 species in Upper Araguaia and 120 species in Middle Rio das Mortes. Seventeen exclusive fish species occurred in Upper Araguaia, whereas 61 were found in the Middle Rio das Mortes basin. Our analysis showed lower diversity of fish in Upper Araguaia than in the Middle Rio das Mortes basin. Considering the exclusive fish species of both basins, the human threats in those regions, and the few existent protected areas, we need a better look at the aquatic biodiversity conservation of this ecosystem.

A bacia do rio Araguaia apresenta a maior diversidade de peixes no bioma Cerrado, muitas dessas são endêmicas e ameaçadas pelas atividades antropogênicas. Apesar dos crescentes esforços para catalogar a diversidade de peixes neotropicais muitas regiões ainda permanecem subamostradas. O objetivo do nosso estudo é complementar a informação sobre peixes de riachos para duas importantes bacias hidrográficas no Cerrado. Amostramos um total de 72 trechos de 50 metros em riachos nas bacias alto rio Araguaia (n = 32) e médio Rio das Mortes (n = 40). Coletamos um total de 14.887 indivíduos distribuídos em 137 espécies, 81 gêneros, 30 famílias e seis ordens. As famílias Characidae, Loricariidae e Cichlidae foram as tiveram maior número de espécies. Encontramos uma grande raridade de espécies de peixes nos riachos amostrados, cerca de 71,5% das espécies apresentaram ao menos até cinco indivíduos coletados e 18 espécies tiveram apenas um único exemplar. As espécies com maior ocorrência nos riachos foram, Astyanax cf. goyacensis Knodus cf. breviceps e Characidium cf. zebra. As duas bacias compartilham aproximadamente 43% das espécies de peixes coletadas. Encontramos 76 espécies para o alto rio Araguaia e 120 espécies para médio Rio das Mortes. Observamos 17 espécies exclusivas para a bacia do alto rio Araguaia e 61 espécies exclusivas para bacia do Médio Rio das Mortes. Nossas análises mostraram que a diversidade de peixes é menor na bacia do alto rio Araguaia quando comparada a bacia do médio Rio das Mortes. Considerando as ameaças antrópicas, o baixo número unidades de conservação e o elevado número de espécies exclusivas presentes em ambas as bacias, existe uma necessidade urgente concentrar esforços na conservação desses ecossistemas

Genetic diversity and species delimitation in Rhamdia (Siluriformes: Heptapteridae) in South America, with a redescription of R. quelen (Quoy amp; Gaimard, 1824).

More than 100 species have been referred to Rhamdia since its description, but in the last revision of the genus more than two decades ago, only eleven species have been considered as valid. Rhamdia quelen was then redefined to include 47 junior synonyms, resulting in a species with a large distribution in the Neotropics, from Mexico to Argentina. Populations of Rhamdia from west of the Andes have been recently removed from the synonymy of R. quelen, and currently there are 27 species recognized in the genus. Most cis-Andean populations, however, remain referred to the R. quelen species complex. In this paper, we use species delimitation methods and multilocus phylogenetic analyses to delimit the species contained in the R. quelen species complex in cis-Andean river drainages. Eighteen MOTUs in the gene tree were recovered with high support. We further demonstrate that the previous designation of a neotype for R. quelen is invalid, and has to be replaced by the proper designation of a neotype from the type locality of the species. The neotype is designated herein and R. quelen is diagnosed and redescribed.

Multiple Sex Chromosomes and Evolutionary Relationships in Amazonian Catfishes: The Outstanding Model of the Genus Harttia (Siluriformes: Loricariidae).

The armored Harttia catfishes present great species diversity and remarkable cytogenetic variation, including different sex chromosome systems. Here we analyzed three new species, H. duriventris, H. villasboas and H. rondoni, using both conventional and molecular cytogenetic techniques (Giemsa-staining and C-banding), including the mapping of repetitive DNAs using fluorescence in situ hybridization (FISH) and comparative genomic hybridization (CGH) experiments. Both H. duriventris and H. villasboas have 2n = ♀56/♂55 chromosomes, and an X1X1X2X2 /X1X2Y sex chromosome system, while a proto or neo-XY system is proposed for H. rondoni (2n = 54♀♂). Single motifs of 5S and 18S rDNA occur in all three species, with the latter being also mapped in the sex chromosomes. The results confirm the general evolutionary trend that has been noticed for the genus: an extensive variation on their chromosome number, single sites of rDNA sequences and the occurrence of multiple sex chromosomes. Comparative genomic analyses with another congeneric species, H. punctata, reveal that the X1X2Y sex chromosomes of these species share the genomic contents, indicating a probable common origin. The remarkable karyotypic variation, including sex chromosomes systems, makes Harttia a suitable model for evolutionary studies focusing on karyotype differentiation and sex chromosome evolution among lower vertebrates.