Rio Uruguay Research Articles

The Upper Rio Paraguay Basin Reveals Another Jewel Hidden: Hypostomus uruguayensis (Loricariidae)

The present work extends the distribution of Hypostomus uruguayensis to the upper Rio Paraguay basin. This species which was originally described from the Rio Uruguay in Southern Brazil and cited to Argentina and Bolivia is here reported for the first time within the Brazilian Midwest. Additionally, the new population was compared to the original description and the holotype of H. uruguayensis, providing a foundation for brief comments on a diagnosis of H. uruguayensis.

Conjectures and refutations: Species diversity and phylogeny of Australoheros from coastal rivers of southern South America (Teleostei: Cichlidae).

Morphological and genetic analyses of species of Australoheros focusing on those distributed in coastal rivers from the Rio de La Plata north to the Rio Buranhém, support recognition of 17 valid species in the genus. Eight species are represented in coastal rivers: A acaroides, A. facetus, A. ipatinguensis, A. oblongus, A. ribeirae, and A. sanguineus are validated from earlier descriptions. Australoheros mboapari is a new species from the Rio Taquari in the Rio Jacuí drainage. Australoheros ricani is a new species from the upper Rio Jacuí. Specimens from the Rio Yaguarón and Rio Tacuary, affluents of Laguna Merín, and tributaries of the Rio Negro, tributary of the Rio Uruguay are assigned to A. minuano pending critical data on specimens from the type locality of A. minuano. Australoheros taura is a junior synonym of A. acaroides. Australoheros autrani, A. saquarema, A. capixaba, A. macaensis, A. perdi, and A. muriae are junior synonyms of A. ipatinguensis. Heros autochthon, A. mattosi, A. macacuensis, A. montanus, A. tavaresi, A. paraibae, and A. barbosae, are junior synonyms of A. oblongus. Heros jenynsii is a junior synonym of A. facetus.

Two new annual fishes (Cyprinodontiformes: Rivulidae) unexpectedly discovered in the highlands of southern Brazil.

Two new species of Austrolebias are described based on specimens collected from temporary pools located in natural grassland landscape within the Araucaria Forest domain at exceptionally high altitudes (~1000 meters a.s.l.). Austrolebias botocudo sp. n. and Austrolebias nubium sp. n. occur, respectively, in drainages of upper rio Apuaê-Inhandava (upper rio Uruguay basin) and upper rio Taquari-Antas (upper rio Jacuí, Laguna dos Patos basin), in the Meridional Plateau of southern Brazil. Despite an intensive survey conducted in the area, only two populations of each species were recorded. Both new species occurs at altitudes that are among the higher recorded for species of the genus, and both are assigned to the subgenus Acrolebias. The new species described herein are easily distinguished for its congeners by the colour pattern of males, by presence of melanophores irregularly distributed in different parts of the body, contact organs cover the body and anal fins, position of fins related with vertebrae, by preopercular and mandibular series of neuromasts united, by a series of morphometric features and by larger maximum standard length. Austrolebias botocudo and A. nubium are distinguished from each other by colour pattern of males, length of contact organs in the flank and number of contact organs in scales of lateral line, dorsal profile of head, number of neuromasts in the preopercular + mandibular series, body depth in females, and by basihyal cartilage length. Additionally, we discuss the conservation status of the new species, and provided an identification key for the species of the subgenus Acrolebias.

Species co-occurrence and population dynamics in annual fish assemblages in the lower Río Uruguay basin

Austrolebias is a genus of annual killifishes from subtropical and temperate grasslands of South America. They coexist in assemblages of up to five species in pools with variable connection to permanent water bodies and complete their entire life cycle within 1 year, terminated by summer desiccation of their habitat. To quantify community and population characteristics of Austrolebias assemblages, we sampled a set of 18 pools in the lowlands of the confluence of Rio Negro and Rio Uruguay in western Uruguay, with 16 sampling trips conducted over the entire seasonal cycle in 2015. Austrolebias bellottii was a ubiquitous and generalist species, A. nigripinnis was more common in pools influenced by active floodplain, A. elongatus (a large predatory species) was rare overall, and four A. alexandri was found only in two pools. Unexpectedly, many pools desiccated in winter (mid season) and some of them supported a second cohort after their re-inundation. Fish abundance and fish density declined steadily prior to pool desiccations. There were indications that adult A. bellottii can survive a short period of habitat desiccation in wet mud, leading to coexistence of an older A. bellottii cohort with a younger A. nigripinnis cohort. Males disappeared from populations at a higher rate, especially towards the end of the season. The overall lifespan of both common species was up to 7 months in pools that did not experience mid-season desiccation. This study provides fundamental demographic parameters for the annual fish in this region.

Xylosandrus crassiusculus . [Distribution map

Abstract A new distribution map is provided for Xylosandrus crassiusculus Motschulsky. Coleoptera: Curculionidae. Hosts: polyphagous on many tree and shrub species. Information is given on the geographical distribution in North America (USA, Maryland, Michigan, Mississippi, Missouri, Nebraska, New Hampshire, New Jersey, New York, North Carolina, Ohio, Oklahoma, Oregon, Pennsylvania, South Carolina, Tennessee, Texas, Virginia, Washington, West Virginia), Central America and Caribbean (Costa Rica, Guatemala, Panama and Puerto Rico), South America (Argentina, Brazil, Amapa, Pernambuco, Rio de Janeiro, Sao Paulo, French Guiana and Uruguay) and Oceania (Australia, Queensland, Guam, New Caledonia, New Zealand, Palau, Papua New Guinea and Samoa).

Importance of the review on floristic and phytosociological studies of the arboreal stratum of the seasonal deciduous forest of the Serra Geral slope, Rio Grande do Sul, Brazil, to support proposals for sustainable management

The Seasonal Deciduous Forest (FED) is a deciduous and human-caused impacted vegetation, occurring at the Upper Rio Uruguay basin and at the southern slope of Serra Geral plateau, Rio Grande do Sul state. The aim of this study is to compile results of tree layer floristics and phytosociological surveys on FED of Serra Geral escarpment with the intention of supporting future interventions for the recovery of degraded areas and sustainable management projects. To obtain the data, was held a narrative review from 62 selected works from the digital libraries of CAPES, Scielo and Google Scholar. For quantitative variables, was calculated the median, standard deviation and amplitude. The hodgepodge of methods used in the surveys conducts to difficulties in comparing data. The median species richness is 54 and the Shannon-Wiener diversity index median is 3.10 nats. The analyzed surveys show very important information to define methods and planning for conservation, degraded area recovery and sustainable use of forest resources.

Occurrence of pesticide residues in fish from south American rainfed agroecosystems

Environmental sustainability of South American rainfed agroecosystems is of current concern. In this work, we evaluate the occurrence of multiple pesticide residues in muscle tissue of wild fish species from two large rivers in South America (Uruguay and Negro Rivers). Two sampling campaigns (representing summer and winter crops) were performed during 2015 targeting a wide biodiversity of fish species used for human consumption (ranging from migratory to non-migratory and from detritivorous to top-predators). Three different localities associated to rainfed agriculture were assessed, two of them enclosed to a RAMSAR site (National Park “Esteros de Farrapos e Islas del Rio Uruguay”). Pesticide residues occurred in muscle tissue of 143 from 149 sampled fishes (96%). Thirty different pesticides were detected at concentrations from <1 to 194μgkg−1. Incidence of pesticides in fish were tightly related to: i) features of the contaminant: (Kow, environmental persistence and mobility) and ii) intensity of use of particular pesticides and land dedicated to rainfed agriculture. Trifloxystrobin, metolachlor and pyraclostrobin showed the highest rates of occurrence. Of great concern is that strobirulins have highest toxicity to fish from those detected compounds. From the pattern of pesticides occurring for non-migratory fish species it was possible to trend important spatial differences related to the intensity of rainfed agriculture. Results suggest a regular exposition of aquatic wild biota to sublethal concentrations of multiple semi-polar pesticides.

First record of blackfin pearlfish Austrolebias nigripinnis (Regan, 1912 (Cyprinodontiformes, Cynolebiidae) from Brazil.

Austrolebias Costa is a genus of annual fish inhabiting temporary wetlands in the Chaco-Pampasic region of southern Brazil, Uruguay, Paraguay, Bolivia and Argentina (Costa, 2006, Nielsen & Pillet, 2015, Alonso et al., 2016). Currently, about 45 species of Austrolebias are known (Costa, 2006, Volcan et al., 2014, Nielsen & Pillet, 2015), and of these, 24 occur in Rio Grande do Sul, the southernmost state of Brazil, distributed across the Rio Uruguay basin and the Patos-Mirim lagoon system and adjacent coastal areas (Volcan et al., 2015).

Review of the Odontesthes perugiae species group from Río de La Plata drainage, with the description of a new species (Atherinomorpha: Atherinopsidae).

Specimens presently identified as belonging to Odontesthes perugiae species group from rio Paraná, rio Uruguay and rio Negro in Argentina, Brazil and Uruguay are revised. Two species are recognized: Odontesthes perugiae, type species of the genus with Odontesthes orientalis as a junior synonym, and a new species described herein. Odontesthes perugiae is redescribed and its distribution restricted to the lower rio Paraná, lower rio Uruguay and rio Negro basins. The new species is endemic from the upper rio Uruguay above Salto do Yucumã (Brazil) or Saltos del Moconá (Argentina) falls. Both species share with the remaining taxa included in the O. perugiae species-group (O. bicudo, O. ledae, O. mirinensis, and O. piquava) the possession of teeth of the outer row on dentary and premaxilla shorter than those in the inner row, being distinguished from them by the number of gill rakers, body measurements and some osteological characters.

Unexpectedly high diversity in a small basin: A taxonomic revision of Eurycheilichthys (Siluriformes: Loricariidae), with descriptions of seven new species

ABSTRACT A taxonomic revision of Eurycheilichthys is provided, and seven new species are described in addition to the two previously known species in this genus: E. pantherinus from the upper rio Uruguay, and E. limulus from the upper rio Jacuí. The genus is diagnosed based on the uniquely derived presence of seven branched pectoral-fin rays, and on the possession of reduced filamentous gill rakers in the oral surface of the hyobranchial skeleton, and presence of a distinct fleshy flap along the posterodorsal margin of the pectoral-fin spine in adult males. The seven new species are described from tributaries to the rio Taquari basin, itself a tributary to the rio Jacuí in Rio Grande do Sul State, southern Brazil. The new species are diagnosed based on color variation, abdominal plate morphology, lip size, parieto-supraoccipital shape, the number of dermal plates, the number of teeth, and body proportions. The high diversity and degree of species endemism in a limited area are discussed and compared to other fish groups. Genetic sequences (GenSeq) of mitochondrial and nuclear DNA, distribution maps, an identification key, and illustrations are presented for all species.

Inventory of the freshwater fishes from a densely collected area in South America-a case study of the current knowledge of Neotropical fish diversity.

We herein analyse the history of the description of the freshwater fish fauna from three drainages in one of the most densely collected areas of Brazil, and possibly of South America, the Rio Grande do Sul State, southern Brazil. An updated inventory of the freshwater fish species from rio Uruguay (partial) in Brazil, Laguna dos Patos (complete) and rio Tramandaí basins (complete) is presented. We found the number of new species described in these drainages increased nearly 56% since 1981, reaching a total of 422 species, but even now 10% of this number still corresponds to undescribed species. This rate of species description suggests that previous estimates of the Neotropical fish fauna are low, and we predict a final number of Neotropical fishes larger than the largest prediction estimate (8,000 species), after other regions of South and Central Americas become densely sampled. We discuss and attempt to demonstrate that species diversity knowledge is historically and strictly related to collecting efforts. We also demonstrate that the ecoregions in eastern South America with the highest density of species per area correspond to the areas more densely sampled in collections, and this may represent a bias in such kinds of analyses. This uneven sampling in Brazilian regions is apparently associated with the uneven distribution of Zoological research centers in different regions of the country. Small-sized species represents an important source of new species, along with little explored regions or little explored habitats, sometimes associated with restricted range species, and species complexes that need revisionary work. In contrast to other Neotropical regions, Atheriniformes are relatively diverse, sharing the fifth place in species richness with Gymnotiformes, and there is a remarkably high number of species of Rivulidae. Eight species are endemic to the rio Tramandaí drainage, 68 to the Laguna dos Patos system, and 78 to the rio Uruguay drainage. Almost 10% of the freshwater fish species are "Critically Endangered", "Endangered" or "Vulnerable" according to the IUCN criteria, with Rivulidae as the family with the largest number of threatened species.

A new species of Gymnogeophagus Miranda Ribeiro from Uruguay (Teleostei: Cichliformes)

ABSTRACT We describe a new species of a substrate-brooding Gymnogeophagus , based on coloration characters. The new species can be distinguished from the remaining substrate-brooding species in the genus by the unique pigmentation of the dorsal fin which consists of light blue, diagonal stripes over a red background in the spiny section and a combination of round, elliptic, and elongated bright blue spots over a red background in the soft section. It can be further distinguished from all other species of Gymnogeophagus by the following combination of characters: a discontinuous bright blue band above the upper lateral line in the humeral area, light blue roundish spots over a red to orange background on the anal fin, and conspicuous bright blue horizontal bands on body. The new species inhabits a wide range of freshwater habitats in the lower rio Uruguay basin, Rio de la Plata coastal drainages and Atlantic Ocean coastal drainages in Uruguay.

Descriptions of five new species of the Neotropical cichlid genus Gymnogeophagus Miranda Ribeiro, 1918 (Teleostei: Cichliformes) from the rio Uruguay drainage

ABSTRACT Gymnogeophagus is a Neotropical cichlid genus distributed in the río Paraguay, rio Paraná and rio Uruguay drainages and also in the coastal rivers of Uruguay and southern Brazil. Its monophyly is supported by two derived features: the absence of supraneurals and the presence of a forward spine in the first dorsal-fin pterygiophore. Herein, five new species of Gymnogeophagus are described from middle to upper tributaries of the rio Uruguay drainage and from the rio Negro. All these new species belong to a clade, which includes G. gymnogenys , easily recognized by sharing two synapomorphies: the absence of an oblique bar between the dorsal border of the eye and the nape, and the possession of a black bar originating in the dorsal contour near the dorsal-fin origin and directed downward and backward on the dorsum. A key to all species of Gymnogeophagus is provided.

Characterization of the ovary fatty acids composition of Rhamdia quelen (Quoy &amp; Gaimard) (Teleostei: Siluriformes), throughout their reproductive cycle

Knowledge about gonad fatty acid composition is important for broodstock diet formulation. This study characterized ovary fatty acid composition of wild female jundiá catfish (Rhamdia quelen) in their different gonadal maturation stages. Female jundiá (n = 36, average weight= 383.8 + 208.8 g) were captured in the rio Uruguay, comprising all seasons. Ovaries were extracted and classified according to their gonadal maturation stage. Gonad-somatic ratio varied significantly among seasons, being higher in spring (3.7), followed by summer (2.2), winter (0.9) and autumn (0.6). Main fatty acids groups detected were: saturated (SFA= 35.5%), monounsaturated (MUFA= 28.1%) and polyunsaturated fatty acids (PUFA= 33.5%). Over the four seasons, palmitic acid was recorded in large quantities, followed by docosahexaenoic acid (DHA) and arachidonic acid (ARA). ARA was present in higher concentrations in immature or maturing ovaries, and its content decreased along the maturation process. Conversely, DHA and eicosapentaenoic acid (EPA) contents increased during maturation. Such variation resulted in an increase in EPA/ARA and DHA/ARA ratios in mature gonads, which can be important for successful breeding. Such findings suggest that jundiá broodstock diets should contain lipids that provide long chain polyunsaturated fatty acids from both the n-3 and n-6 series to ensure gonadal maturation completion.

A new species of Astyanax Baird &amp; Girard (Ostariophysi: Characidae) from the rio Taquari-Antas basin, southern Brazil

A new Astyanax is described from the rio Taquari-Antas basin, rio Jacuí drainage, laguna dos Patos system, Rio Grande do Sul State, Brazil. The new species is distinguished from its congeners inhabiting the rio Uruguay, laguna dos Patos and rio Tramandaí basins by the presence of two vertically elongated humeral spots, the anterior humeral spot with the upper portion wider than the lower portion and slightly directed forward, 37-39 perforated scales along the lateral line, 14 scale rows around caudal peduncle, 2-4 maxillary tricuspid teeth, 24-28 branched anal-fin rays, bony hooks on all fins of mature males, and conspicuous caudal peduncle spot. Furthermore, the new species differs from its congeners by body depth (37.9-45.9% of standard length), preanal distance (62.4-69.1% of SL), anal-fin base length (29.7-35.6% of SL), and orbital diameter (29.5-38.2% of head length).

Fishes from rio Ibirapuitã basin, Environmental Protection Area of Ibirapuitã, Pampa Biome

The fish species herein presented were collected in streams, swamps and rivers of the rio Ibirapuitã basin, middle rio Uruguay basin, in the Environmental Protection Area of Ibirapuitã. Samplings resulted in 72 species distributed in 51 genera, 21 families, and six orders. This study represents the first fish survey in the EPA of Ibirapuitã (Pampa biome).

Three new species of Astyanax from drainages of southern Brazil (Characiformes: Characidae)

Three new species of Astyanax are described from southern Brazil: A. dissensus and A. xiru from the laguna dos Patos system and rio Uruguay basin, the first species also occurring in the rio Tramandaí system, and A. procerus from the laguna dos Patos system. Astyanax procerus and A. xiru possess outer row premaxillary teeth pentacuspid and inner row heptacuspid, maxillary with one tri- to pentacuspid teeth, 18-23 branched anal-fin rays, and two humeral spots. Astyanax procerus has the largest body depth (38.3-46.0% of SL), while A. xiru has the lowest body depth (32.5-37.5% of SL) among the three species. The characters combination can distinguish these species from its congeners. Astyanax dissensus distinguish from Astyanax species by the presence of one developed heptacuspid teeth on maxillary, 22-28 branched anal-fin rays, 35-39 perforated scales along the lateral line, two humeral spots, conspicuous lateral band continuous on middle caudal rays, 6-7 scale row between dorsal-fin origin and lateral line, and head length 22.7-27.3% of SL. All three species has the predorsal region of the body scaled. An identification key to the species of Astyanax species from the rio Uruguay basin, and laguna dos Patos and rio Tramandaí systems is provided.

A new species of Astyanax from headwater streams of southern Brazil (Characiformes: Characidae).

Astyanax pirabitira, new species, is described from the upper portion of the rio das Antas, laguna dos Patos system, and from the rio Pelotas, upper rio Uruguay drainage, Rio Grande do Sul State, Brazil. The new species belongs to the A. scabripinnis species complex and differs from its congeners by a combination of characters, viz., body depth (27.1-34.0% of standard length), narrow interorbital width (22.2-28.7% of head length), head depth (72.9-97.0% of HL), number of branched anal-fin rays (15-20), number of lateral line scales (37-40), one or two maxillary teeth, two humeral spots and absence of secondary sexual characters (bony hooks in the fins or other differences in the morphology). Comments on the endemic fish fauna of the region are presented.

Geographic and seasonal variation analysis of digestive morphology in the catfish Iheringichthys labrosus along lower R&amp;iacute;o Uruguay

The study of geographic variation of individual traits is an important component of evolutionary research, in that individual morphological features can be subjected to multiple selective pressures. The present work is aimed to analyze the geographic and seasonal varia- tion in several digestive traits in Iheringichthys labrosus along three localities in the lower Rio Uruguay. Statistically significant differences among locations and between seasons were found for all the variables assessed, the most noticeable of differences being observed were intestinal length, intestine weight, and liver weight. In part, these differences could be an adaptive response to changes in food availability and/or in the energetic costs of reproduction. Results obtained herein also suggest that individuals of this species spend enough time in each locality as to show

A diversidade da cultura fronteiriça a Oeste da província do Rio Grande de São Pedro: o comércio e a paróquia de São Patrício de Itaqui (1850-1870)

This article analyzes the organization of business activity that is established in the Province of Rio Grande de São Pedro, in the second half of the nineteenth century, from the Parish of St. Patrick Itaqui, between 1850 and 1870. Seeks to identify as manifested commercial activities in a region bordering open and susceptible to the flow of goods, people and trade associations which went along the Rio Uruguay, helping to boost the performance of traders and dealers in this society. Primary sources, legal and administrative, helped identify through quantitative research a trade that went through the action of a number of agents and private strategies of accumulation of funds that multiply in this border area, making it possible to expand the activities of the various lines of business. Thus, trade has created multiple strategies that society border favorable to mercantile interests that we are willing to consider.