A new species of Centromochlus (Siluriformes,Auchenipteridae, Centromochlinae) from the middle Rio Tocantins basin,Brazil

A new species of the catfish genus Centromochlus (Auchenipteridae, Centromochlinae) is described. The new species is diagnosed by having numerous dark rounded blotches over the body and fins, dorsal‐fin spine with serrations anteriorly and smooth posteriorly, anal fin of mature males with three unbranched and seven branched rays, anterior nuchal plate absent and posterior nuchal plate not extended ventrally. The new species is described from a small stream in the Estação Ecológica Serra Geral de Tocantins, a natural reserve in the centre of the Brazilian Cerrado, close to the watershed between the Rio Tocantins and the Rio São Francisco basins. The new species is possibly the sister taxon to the recently described Centromochlus meridionalis from the upper Rio Tapajós. Those two species share with Centromochlus perugiae, from the upper Amazon and upper Paraguay, derived features associated with the modified anal fin in sexually mature males.     

The Electric Glass Knifefishes of the Eigenmannia trilineata species‐group (Gymnotiformes: Sternopygidae): monophyly and description of seven new species

Eigenmannia trilineata López and Castello, 1966 (Sternopygidae) was described from the Río de La Plata basin and subsequently cited from most South American river basins. Questions about the limits of this species raise the possibility of the occurrence of undescribed species misidentified as E. trilineata. Herein we propose the Eigenmannia trilineata species group for species that share the presence of the superior medial stripe on the flank. This group comprises: E igenmannia antonioi sp. nov. , from the Rio Anapu, Rio Amazonas basin; E igenmannia desantanai sp. nov. , from the Rio Cuiabá, Rio Paraguay basin; E igenmannia guairaca sp. nov. , from the Riacho Água do Ó, upper Rio Paraná basin; E igenmannia matintapereira sp. nov. , from the Rio Uneiuxi and Rio Urubaxi, Rio Negro basin; Eigenmannia microstoma (Reinhardt, 1852), from the Rio São Francisco basin; E igenmannia muirapinima sp. nov. , from small tributaries of the Rio Amazonas; E igenmannia pavulagem sp. nov. , from the tributaries of Rio Capim, Rio Guamá basin; E. trilineata, from the lower Rio Paraná basin and Río de La Plata basin; Eigenmannia vicentespelaea Triques, 1996, from São Vicente I and II caves, Rio Tocantins basin; and E igenmannia waiwai sp. nov. , from the Rio Trombetas basin. These species can be distinguished from each other by unique sets of meristics, morphometrics, osteological and colour pattern features. © 2015 The Linnean Society of London     

Moenkhausia celibela: a new species from the Amazon basin,Brazil (Characiformes: Characidae)

A new species of Characidae, Moenkhausia celibela, is described from the Rio Amazonas at Santarém, Rio Maraú, several localities in the Rio Tapajós, Rio Curuá‐Una, Rio Xingu and Rio Jari, all from the Amazon basin, Brazil. The new species is distinguished from its congeners, except species included in Géry's 1992 Moenkhausia lepidura group, by presenting a dark blotch on the upper caudal‐fin lobe, and the lower lobe is hyaline or light grey. Moenkhausia celibela is distinguished from the species of the M. lepidura group by the absence of a humeral spot and the presence of a roughly triangular and dark spot at the caudal‐fin base, extending posteriorly along the middle caudal‐fin rays, and distinctly separate from the spot on the upper caudal‐fin lobe.     

Archolaemus janeae (Gymnotiformes,Teleostei): First insights into karyotype and repetitive DNA distribution in two populations of the Amazon

Archolaemus, one of the five genera of Neotropical freshwater fish of the family Sternopygidae (Gymnotiformes), was long considered a monotypic genus represented by Archolaemus blax. Currently, it consists of six species, most of them occurring in the Amazon region. There are no cytogenetic data for species of this genus. In the present study, we used classical cytogenetics (conventional staining and C‐banding) and molecular cytogenetics (probes of telomeric sequences and multigenic families 18S rDNA, 5S rDNA, and U2 snDNA) to study the karyotype of Archolaemus janeae from Xingu and Tapajós rivers in the state of Pará (Brazil). The results showed that the two populations have identical karyotypes with 46 chromosomes: four submetacentric and 42 acrocentric (2n = 46; 4m/sm + 42a). Constitutive heterochromatin occurs in the centromeric region of all chromosomes, in addition to small bands in the interstitial and distal regions of some pairs. The 18S rDNA occurs in the distal region of the short arm of pair 2; the 5S rDNA occurs in five chromosome pairs; and the U2 snDNA sequence occurs in chromosome pairs 3, 6, and 13. No interstitial telomeric sequence was observed. These results show karyotypic similarity between the studied populations suggesting the existence of a single species and are of great importance as a reference for future cytotaxonomic studies of the genus.     

Three new species of Curimatopsis (Characiformes: Curimatidae) from the Amazon basin

Three new species of Curimatopsis are described from major tributaries of the Amazon basin. Curimatopsis guaporensis n. sp., from the Rio Madeira, belongs to the Curimatopsis evelynae clade and can be distinguished by the distinctive shape of the dark blotch on the caudal peduncle and by the position and shape of the nostrils. Curimatopsis pallida n. sp., from the Rio Negro, also related to C. evelynae, is distinguished from all congeners by the complete absence of pigmentation on the lateral surface of the caudal peduncle. Curimatopsis jaci n. sp., apparently endemic to the upper Rio Tapajós, belongs to the Curimatopsis macrolepis clade and differs from all congeners in details of body pigmentation. Meristic and morphometric features supplement diagnoses for the three new species. These species are hypothesized to belong to the two main clades of Curimatopsis on the basis of previous studies of osteology and external morphology and supplement a recent genetic study that revealed several cryptic and yet undescribed species within the genus. An updated identification key to the species of Curimatopsis is also provided.     

Two new species of Leporinus (Characiformes: Anostomidae) from the Brazilian Amazon,and redescription of Leporinus striatus Kner 1858

Two new species of Leporinus are described from tributaries of the Rio Amazonas in Brazil. One species is known from the Jari and Tapajós River basins, and is identified on the basis of a gas bladder reduced in size, a dark midlateral stripe on the body, dark transverse bars on the dorsum, a subinferior mouth, three teeth on the premaxilla, four teeth on the dentary and 16 scale rows around the caudal peduncle. The second new species is known from the Tocantins, Xingu and Tapajós River basins, and is identified on the basis of three dark longitudinal stripes on the body, a subinferior mouth, three teeth on the premaxilla, four teeth on the dentary and 12 scale rows around the caudal peduncle. In addition, Leporinus striatus is redescribed based on type and additional specimens from the Río de La Plata, Amazonas, Orinoco, Atrato, Magdalena and Sinu River basins. Leporinus striatus is identified on the basis of four dark longitudinal stripes on the body, a subterminal mouth, three teeth on the premaxilla, four teeth on the dentary and 16 scale rows around the caudal peduncle.     

A new sexually dichromatic miniature Hyphessobrycon (Teleostei: Characiformes: Characidae) from the Rio Formiga,upper Rio Juruena basin,Mato Grosso,Brazil, with a review of sexual dichromatism in Characiformes

Hyphessobrycon myrmex sp. nov., is described from the Rio Formiga, upper Rio Juruena, upper Rio Tapajós basin, Mato Grosso, Brazil. The new species can be distinguished from congeners by having the lower half of the body deeply pigmented with dark chromatophores, chromatophores concentrated above the anal fin and forming a broad, diffuse, dark midlateral stripe and by having a dense concentration of dark chromatophores along unbranched dorsal‐fin rays and distal portions of the two or three subsequent branched rays. In life, H. myrmex exhibits a conspicuous sexual dichromatism, with adult males red to orange and females and immatures pale yellow. A list containing 108 sexually dichromatic taxa in six families of Characiformes is provided and the distribution of this poorly known type of dimorphism across the Characiformes is discussed.     

Eunotia amazonica sp. nov. (Bacillariophyta), a common stalk-forming species from the Rio Negro basin (Brazilian Amazon)

A new stalk-forming diatom was observed at high relative abundances on periphytic samples collected in the Rio Negro hydrographic basin (Brazilian Amazon) and is here described using light and scanning electron microscopy. We also present ecological preferences of the new species. Eunotia amazonica sp. nov. co-dominated periphytic samples collected during the rainy seasons of 2013 and 2014 near the city of Manaus (Amazonas, Brazil). The main diagnostic feature of the new species is the stalk-forming growth form (‘Cymbella-like’) illustrated here for the first time in the genus Eunotia Ehrenberg. Previous reports on growth forms in common European databases for this genus included colonial (‘ribbon-like’) but also ‘mobile’, ‘fixed by pads’ or ‘without structures of fixation’. We demonstrated that the three dominant Eunotia species in periphytic samples from the Rio Negro all exhibited distinct ‘growth forms’ or habits: Eunotia amazonica sp. nov. (stalked), Eunotia intricans Metzeltin & Lange-Bertalot (ribbon-like) and Eunotia rabenhorstiana (Grunow) Hustedt (branched-arborescent). The high diversity of species, many of which are unknown to science, as well as the poorly known life-forms and habits of the Eunotiaceae in the region, partially prevent the use of metrics based on life-form to assess ecological changes. Generic assumptions based on robust statistical methods may obscure reality and lead to biased conclusions of diatom community changes in poorly explored regions such as Neotropical freshwater rivers, where the Eunotiaceae are largely dominant, particularly in the Amazon basin.     

Geographic distribution and population characteristics of the endangered white-fronted spider monkey (<Emphasis Type="Italic">Ateles marginatus</Emphasis>) on the lower Tapajós River in central Brazilian Amazonia

The white-fronted spider monkey, Ateles marginatus, is endemic to Brazilian Amazon between the Tapajós and Xingu Rivers, and is classified as endangered due primarily to habitat loss. This study presents data on the distribution and relative abundance of the species in the northwestern corner of its distribution, on the lower Tapajós River, centered on the 545,000 ha Tapajós National Forest (Flona Tapajós). Quantitative data were collected in line transect surveys at 14 sites, and confirmatory interviews were conducted at these, and a further four sites. The results indicate that A. marginatus is extinct or extremely rare at sites in the northern extreme of the study area, but is relatively widespread further south, except in very small fragments (<100 ha). While the present-day occurrence of A. marginatus is clearly affected by habitat fragmentation, the species’ original distribution appears to have been characterized by local lacunas, determined by factors relating to habitat quality. While hunting pressure does not seem to be a major threat at the present time, competition with a second atelid, Alouatta discolor, may have reinforced the effects of habitat disturbance in some areas, especially smaller fragments. Grouping patterns were typical of the genus, including an apparent female bias in the sex ratio of adults. Overall, the results indicate an ongoing decline in the occurrence of A. marginatus within the study area, local extinction, especially in smaller fragments, and an urgent need for the establishment of effective conservation measures.     

New species of Moenkhausia Eigenmann (Characiformes: Characidae) from Rio Xingu and Rio Tapajós basins,Brazil, with comments on a putative case of polymorphic Batesian mimicry

A new species of Moenkhausia is described from Rio Xingu and Rio Tapajós basins, Brazil. The new species is distinguished from its congeners, except from Moenkhausia moisae, by having more scales in the lateral series, 43–47 (v. 23–41 in the remaining congeners). The new species is distinguished from M. moisae by its colour pattern, which consists of a dark midlateral stripe, and an asymmetrical caudal blotch (inconspicuous or faded in specimens from the Rio Arinos) continuous with the midlateral stripe (v. narrow dark midlateral line and conspicuous, regularly rounded and symmetrical blotch not continuous with the midlateral line). The new species is putatively assumed to be mimetic to Jupiaba apenima, in the Rio Xingu and Rio Teles Pires drainages, and to Jupiaba yarina in the Rio Arinos. The two species of Jupiaba are sympatric and remarkably similar in size, general external morphology and colouration to the new species. A small difference occurs in the colouration between the two species of Jupiaba and is also observed in the two respectively sympatric morphotypes of the new species of Moenkhausia. The occurrence of polymorphic Batesian mimicry is therefore discussed for neotropical freshwater fishes.     

Vacuolaria tropicalis,a new species of Chloromonad from Southern Brazil

Vacuolaria tropicalis sp. nov. is here described as a new species of Chloromonadophyceae, observed in material collected during the summer of 1968–1969 from an artificial pool behind the greenhouses in the São Paulo Botanical Garden in the city of São Paulo. It is distinguished from the three previously described species of the genus chiefly by cell shape and by colour and localisation of the chromatophores.     

Genetic relationships of Plagioscion squamosissimus (Perciformes,Sciaenidae) from five Neotropical river basins evaluated using mitochondrial atpase6/8 gene sequences

The genetic relationships of native or introduced Plagioscion squamosissimus in five Brazilian Neotropical basins were evaluated using the mitochondrial atpase6/8 genes. Results revealed that the population of the Tocantins River basin is more basal than the native populations of the Amazon and Parnaíba River basins. Moreover, the populations of P. squamosissimus that were introduced in the São Francisco and upper Paraná River basins originated from the population of the Parnaíba River.     

Taxonomic review of Bourguyiinae,cladistic analysis,and a new hypothesis of biogeographic relationships of the Brazilian Atlantic Rainforest (Arachnida: Opiliones,Gonyleptidae)

The subfamily Bourguyiinae Mello‐Leitão, 1923 (Gonyleptidae) is revised, and both phylogenetic and biogeographic hypotheses are proposed. Bourguyiinae is monophyletic, and is the sister group of the remainder of the Gonyleptidae species used for analysis, except for the Metasarcinae, which collectively is the sister group of Metavononoides orientalis Mello‐Leitão, 1923 (Cosmetidae). Bourguyiinae is divided into two genera: Bourguyia (six species) and Asarcus (four species). The genus‐level synonyms proposed here are as follows: Caldasius, Styloleptes, and Stylopisthos are junior synonyms of Bourguyia; Bogdana, Cnemoleptes, and Opisthoplites are junior synonyms of Asarcus. The species synonyms proposed here are as follows: Afranius amarali Mello‐Leitão, 1934 is a junior synonym of Bourguyia albiornata Mello‐Leitão, 1923 ; Drastus hamatus Roewer, 1943 and Styloleptes conspersus Piza, 1943 are junior synonyms of Bourguyia trochanteralis Roewer, 1930 ; Asarcus corallipes Simon, 1879 , Asarcus lutescens Sørensen, 1884 , Asarcus pallidus Mello‐Leitão, 1923 , and Opisthoplites ypsilon Sørensen, 1884 are junior synonyms of Asarcus longipes Kollar in Koch, 1839 ; Asarcus nigriconspersus Soares & Soares, 1945 is a junior synonym of Asarcus ingenuus Melo‐Leitão, 1940. New species described are: Bourguyia bocaina sp. nov. (Serra da Bocaina, São José do Barreiro, São Paulo), Bourguyia vinosa sp. nov. (E.B. Boracéia, Salesópolis, São Paulo), and Asarcus putunaberaba sp. nov. (Parque Nacional do Caparaó, Alto Caparaó, Minas Gerais). Bourguyiinae is endemic to the Atlantic Rainforest in the Brazilian states of Minas Gerais, Rio de Janeiro, São Paulo, and Paraná. Based on the modified data matrix of Pinto‐da‐Rocha et al., we propose a new biogeographical hypothesis for the Atlantic Rainforest. We suggest that Bourguyiinae species were originally distributed from the coastal region of Paraná to the north of Rio de Janeiro and south‐east of Minas Gerais, with subsequent dispersals both to northern and southern areas. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 156 , 319–362.     

A new species of the leopard pleco genus Pseudacanthicus (Siluriformes: Loricariidae) from the Rio Xingu,Brazil

The genus Pseudacanthicus comprises six valid species distributed in the Amazon basin and Caribbean coastal drainages from Guyana to French Guiana: P. serratus, P. fordii, P. histrix, P. spinosus, P. leopardus and P. pitanga. A new species of Pseudacanthicus is described from the Rio Xingu Basin, distinguished from its congeners by the following combination of characters: presence of anastomose dark blotches forming continuous zigzag bands alongside longitudinal keels; presence of dark blotches on ventral surface of body and head; all fins with orange to red colour on unbranched rays and sometimes subsequent branched rays. Brief comments on ornamental fisheries and conservation of the new species are also provided.     

Taxonomic revision of the South American fish genus Chalceus Cuvier (Teleostei: Ostariophysi: Characiformes) with the description of three new species

The Neotropical characid fishes of the genus Chalceus Cuvier, 1817, are reviewed. In total, five species are recognized (including three new species). Chalceus epakros sp. nov. is the most widespread geographically, occurring in many rivers of the Amazon basin, the Río Orinoco and in the Essequibo River drainage in Guyana. Chalceus guaporensis sp. nov. is restricted to the upper Rio Madeira, Rio Guaporé and Río Madre de Dios, of Brazil, Bolivia and Peru, respectively. Chalceus spilogyros sp. nov. occurs only in the Rio Trombetas, lower Rio Tapajós and lower Rio Madeira drainages. Chalceus macrolepidotus Cuvier occurs in the Rio Negro drainage, middle and lower Río Orinoco basin and in the rivers of the Atlantic slopes of the Guianas, and Chalceus erythrurus Cope in the Rio Amazonas and Rio Solimões to Río Ucayali drainage in Peru. Chalceus ararapeera Cuvier & Valenciennes and Creagrutus pellegrini Puyo are considered synonyms of C. macrolepidotus , and Pellegrinina heterolepis Fowler is placed into the synonymy of C. erythrurus . Characters pertaining to the monophyly of Chalceus are discussed and a key to species is presented.  © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society , 2004, 140 , 103−135.     

Teleocichla preta,a new species of cichlid from the Rio Xingu Basin in Brazil (Teleostei: Cichlidae)

Teleocichla preta nov. sp. inhabits the rapids along the Rio Xingu and lower portion of the Rio Iriri. It is the largest species in the genus, reaching 121·3 mm standard length (L_S) while others do not reach more than 87·8 mm L_S. Teleocichla preta is distinguished from all other species of Teleocichla by the unique blackish (in live specimens) or dark brown (preserved specimens) overall colouration of the body, which masks the faint vertical bars or zig‐zag pattern of blotches on the flanks. Teleocichla preta also has a deeper body and a deep laterally compressed caudal peduncle, unlike any other congener, as well as a stout lower pharyngeal tooth plate bearing molariform teeth on its median area.     

A new species of the Neotropical loricariid Hypostomus cochliodon group (Hypostominae) from the lower Rio Tapajós basin,Brazilian Amazon

A new species of Hypostomus with spoon-shaped teeth is described from the Rio Cupari basin, a right margin affluent of the lower Rio Tapajós, Pará State, Brazil. The new species inhabits rocky bottom areas in the main channel of Rio Cupari and its tributaries. The new species can be distinguished from all its congeners, except from the Hypostomus cochliodon group, by having six to eight spoon-shaped teeth, dentaries angled at less than 80° and the absence of a notch between the hyomandibular and the metapterygoid. The new species is distinguished from all species of the H. cochliodon group by its unique colour pattern, containing dark vermiculations on head and anterior portion of the trunk, and by the absence of medial buccal papillae.     

Two new species of cossonine weevils,Araucarius kuscheli spec. nov. and A. crassipunctatus spec. nov. (Coleoptera: Curculionidae) from southern Brazil

The occurrence of cossonine weevils of the genus Araucarius Kuschel 1966 is limited to South American Araucaria trees. Adults and larvae of two new species, Araucarius kuscheli spec. nov. and A. crassipunctatus spec. nov. have been found under the bark of Araucaria angustifolia trees in São Francisco de Paula, Rio Grande do Sul, Brazil. A key for the adults of the genus Araucarius including the two new species and the already known two Brazilian and four Chilean species is presented.