Ontogeny of the brain of Microglanis garavelloi Shibatta and Benine 2005 (Teleostei: Siluriformes: Pseudopimelodidae).

The gross brain morphology and the peripheral olfactory organ of Microglanis garavelloi are described throughout development, and the relationship of these organs to the general behaviour of the species is discussed. During the development, the main brain subdivisions undergo a series of morphological changes keeping a relatively constant volume increase. However, we observed different growth rates in the brains of males and females when these were compared. During the maturation process, a series of hormonal events result in the development of some secondary sexual traits in the brain of male specimens, like faster growth rate of brain areas linked to motor control, olfactory and visual responses. The number of olfactory-organ lamellae increases continuously in both males and females, during their maturation period. These results suggest that changes may be caused by cognitive demands that this species is exposed to throughout its lifespan. The gross morphological arrangement of the central nervous system indicates shared patterns with other members of the family Pseudopimelodidae.

New species of Rhyacoglanis (Siluriformes: Pseudopimelodidae) from rio Tocantins basin, northern Brazil

A new species of Rhyacoglanis is described from the rapids of Jatobal, Pará State, Brazil. This species differs from the congeners by fusing hypurals 3, 4, and 5 (vs. hypural 5 free). It also differs from the other species, except for Rhyacoglanis epiblepsis, by the color pattern with numerous dark spots on the body, short post-cleithral process, rounded pectoral and caudal fins, and incomplete lateral line. This species is known only from the type locality, which is currently flooded by the Tucuruí reservoir.(AU)

Uma nova espécie de Rhyacoglanis é descrita das corredeiras de Jatobal, estado do Pará, Brasil. Essa espécie difere das congêneres pela fusão dos hipurais 3, 4 e 5 (vs. hipural 5 livre). Também difere das demais espécies, exceto de Rhyacoglanis epiblepsis, pelo padrão de colorido com inúmeras pintas escuras no corpo, processo pós-cleitral curto, nadadeiras peitoral e caudal arredondadas, e linha lateral incompleta. Essa espécie é conhecida apenas da localidade tipo, que atualmente se encontra inundada pelo reservatório de Tucuruí.(AU)

Phylogeny of the Neotropical Pacman catfish genus Lophiosilurus (Siluriformes: Pseudopimelodidae)

Lophiosilurus is a monotypic genus represented by L. alexandri, a species endemic to the São Francisco river basin, Brazil. In previous phylogenetic analyses, the genus has been recovered as the sister group of Cephalosilurus. However, few species of Cephalosilurus or few characters were included in those studies. Thus, the current study aims to test the monophyletic hypothesis of the genera Lophiosilurus and Cephalosilurus with a more comprehensive phylogenetic analysis, including all Cephalosilurus species and a representative number of characters. Phylogenetic analyses of 18 terminal taxa (15 ingroups and three outgroups) were conducted based on a combined 75 character matrix, including 70 discrete morphological characters concerning osteology and neuroanatomy, four continuous characters, and the geometric morphometry of the head. The monophyly of the family Pseudopimelodidae was highly supported, and Cephalosilurus is synonymized with Lophiosilurus. The recovered phylogeny of the genus was (L. albomarginatus (L. nigricaudus (L. apurensis (L. fowleri, L. alexandri)))).(AU)

Lophiosilurus é um gênero monotípico representado por L. alexandri, uma espécie endêmica da bacia do rio São Francisco, Brasil. Em análises filogenéticas anteriores, o gênero foi recuperado como grupo irmão de Cephalosilurus. No entanto, poucas espécies de Cephalosilurus ou poucos caracteres foram incluídos nesses estudos. Assim, este estudo tem como objetivo testar a hipótese de monofilia dos gêneros Lophiosilurus e Cephalosilurus, com uma análise filogenética mais abrangente, incluindo todas as espécies de Cephalosilurus e um número representativo de caracteres. As análises filogenéticas de 18 táxons terminais (15 do grupo interno e três grupos externos) foram realizadas com base em uma matriz combinada de 75 caracteres, incluindo 70 caracteres morfológicos discretos de osteologia e neuroanatomia, quatro caracteres contínuos e um de morfometria geométrica da cabeça. A monofilia da família Pseudopimelodidae foi altamente apoiada e Cephalosilurus foi sinonimizado como Lophiosilurus. A filogenia recuperada do gênero foi (L. albomarginatus (L. nigricaudus (L. apurensis (L. fowleri, L. alexandri))).(AU)

Electric eels galore: microsatellite markers for population studies

Fourteen novel microsatellite loci are described and characterized in two species of electric eels, Electrophorus variiand E. voltaifrom floodplains and rivers of the Amazon rainforest. These loci are polymorphic, highly informative, and have the capacity to detect reliable levels of genetic diversity. Likewise, the high combined probability of paternity exclusion value and low combined probability of genetic identity value obtained demonstrate that the new set of loci displays suitability for paternity studies on electric eels. In addition, the cross-amplification of electric eel species implies that it may also be useful in the study of the closely related E. electricus, and to other Neotropical electric fishes (Gymnotiformes) species as tested herein.(AU)

Catorze novos loci microsatélites são descritos e caracterizados em duas espécies de poraquês, Electrophorus varii e E. voltai de planícies alagadas e rios da floresta amazônica. Esses loci são polimórficos, altamente informativos e têm a capacidade de detectar níveis confiáveis de diversidade genética. Da mesma forma, o alto valor de exclusão de paternidade combinado com a baixa probabilidade de identidade genética demonstra que o novo conjunto de loci exibe adequação para estudos de paternidade em poraquês. Além disso, a amplificação cruzada de espécies de peixes elétricos implica que também pode ser útil no estudo da espécie intimamente relacionada E. electricus, e de outras espécies de peixes elétricos neotropicais (Gymnotiformes).(AU)

New species of bumblebee catfish of the genus Batrochoglanis Gill, 1858 (Siluriformes: Pseudopimelodidae) from the Aripuanã River basin, Mato Grosso, Brazil.

A new species, Batrochoglanis castaneus, is described from the Aripuanã River basin, Brazil. It differs from congeners, except B. raninus and B. transmontanus, by the dark brown color of the body and a dark brown stripe on the caudal fin. The new species differs from B. raninus by the longer maxillary barbel, longer prepelvic length, greater prepectoral length, smaller anal-fin base length, and smaller head depth. The new species differs from B. transmontanus by the longer caudal-fin dorsal lobe, presence of a hyaline spot or stripe on pelvic, dorsal, and anal fins, longer maxillary barbel, longer pectoral-fin, and dorsal-fin spines, greater eye diameter, smaller head depth, and larger mouth width. A metapterygoid anteriorly bifurcated and the lateral line reaching the adipose fin present in the new species are interpreted as synapomorphies of Batrochoglanis. On the other hand, the distribution of pore and neuromasts of the laterosensory system of the head seems to be very conservative in the family. The new species is known only from the Aripuanã River basin, reinforcing its characteristics as an area of endemism for fishes in the Amazon basin.

Influence of microhabitat on the richness of anuran species: a case study of different landscapes in the Atlantic Forest of southern Brazil.

Environmental heterogeneity is a factor which can help explain the higher local species richness. The objective of this study was to test if richness and composition of anurans species are related to available microhabitats and landscape type of sampled sites. We assume that a higher number of microhabitats increase environmental heterogeneity and this, in turn, affects species richness of amphibians. We performed the study in the Mesophytic Semideciduous Forest, a vegetation type within Atlantic Forest Domain. Between October 2010 and February 2011, we sampled 23 water bodies located in the agricultural, forest, and urban landscapes. The species richness was determined using survey at breeding sites methodology, and the availability of microhabitats was estimated visually. Thirty-four anuran species belonging to 12 families were recorded. The species richness in water bodies ranged from two to 13 species. The highest species richness was recorded in environments with a higher number of microhabitats, while the species composition in water bodies was partially grouped according to the predominant landscape type that is agricultural, forest, forest edge or urban. Our results suggest that species use specific environments (e.g. landscapes, habitat and microhabitat) for their reproductive activities.

Reappraisal of the systematics of Microglanis cottoides (Siluriformes, Pseudopimelodidae), a catfish from southern Brazil.

The southern region of Brazil is characterized by high species diversity and endemism of freshwater fishes distributed across geographically isolated river basins. Microglanis cottoides has a widespread range across these river basins and occurs in sympatry with other endemic species of the genus (e.g. M. cibelae, M. eurystoma, and M. malabarbai). Herein we tested the monophyly of M. cottoides and presented for the first time information about the molecular phylogeny of species in the genus. The results suggest that M. cottoides currently forms a non-monophyletic group which includes populations endemic to the Uruguay River basin that are more closely related to M. malabarbai, and excludes M. cibelae, found to be nested within M. cottoides. Based on an integrative approach using morphological and molecular data, we propose M. cibelae as a junior synonym of M. cottoides, and the populations of the Uruguay River basin previously assigned to M. cottoides in fact belong to M. malabarbai. Our molecular phylogeny shows that M. cottoides is sister to M. parahybae, which is also a coastal species, and M. malabarbai is sister of M. garavelloi, both endemic to inland river basins. The time-calibrated phylogeny indicates that the separation between inland and the coastal clades occurred in the Tertiary period, and that the species within the coastal basins diverged in the Pliocene, which overlaps with the diversification times estimated for the two inland species as well. This pattern of diversification corroborates some previous studies with other fishes from the same region.

Genetic Diversity of the Endangered Neotropical Cichlid Fish (Gymnogeophagus setequedas) in Brazil.

Gymnogeophagus setequedas is a rare and rheophilic species of tribe Geophagini, considered endangered in Brazilian red lists. Its previously known geographical distribution range was the Paraná River basin, in Paraguay, and a tributary of the Itaipu Reservoir in Brazil. Since its description no specimens have been collected in the original known distribution area. However, recent records of G. setequedas in the lower Iguaçu River, in a region considered highly endemic for the ichthyofauna, extended the known geographical distribution and may represent one of the last remnants of the species. The aim of this study was to estimate the genetic diversity and population structure of G. setequedas, using microsatellite markers and mitochondrial haplotypes, in order to test the hypothesis of low genetic diversity in this restricted population. Muscular tissue samples of 86 specimens were obtained from nine locations in the Lower Iguaçu River basin, between upstream of the Iguaçu Falls and downstream of the Salto Caxias Reservoir. Seven microsatellites loci were examined and a total of 120 different alleles were obtained. The number of alleles per locus (NA) was 17.429, effective alleles (NE) 6.644, expected heterozygosity (HE) 0.675, observed (HO) heterozygosity 0.592, and inbreeding coefficient (FIS) 0.128. Twelve haplotypes in the D-Loop region were revealed, with values of h (0.7642) and π (0.00729), suggesting a large and stable population with a long evolutionary history. Thus, both molecular markers revealed high levels of genetic diversity and indicated the occurrence of a single G. setequedas population distributed along a stretch of approximately 200 km. The pattern of mismatch distribution was multimodal, which is usually ascribed to populations in demographic equilibrium. Nevertheless, the construction of a new hydroelectric power plant, already underway between the Salto Caxias Reservoir and Iguaçu Falls, could fragment this population, causing loss of genetic diversity and population decline, and for this reason it is necessary to maintain the Iguaçu River tributaries and downstream area from the Lower Iguaçu Reservoir free of additional dams, to guarantee the survival of this species.

A new species of Bryconamericus (Characidae: Stevardiinae: Diapomini) from the upper rio Paraná basin, Brazil

Bryconamericus is the most diverse genus within Stevardiinae, comprising 61 valid species distributed in Cis- and Trans-Andean basins from Panama in Central America to northern Argentina in South America. Three species are known from the upper rio Paraná basin: B. exodon, B. iheringii, and B. turiuba. Herein we describe a new species of Bryconamericus from the upper rio Paraná basin inhabiting tributaries of Ivaí, Piquiri, and Tibagi basins, Paraná State, Brazil. The new species differs from its congeners by the presence of unaligned teeth in the outer tooth row of the premaxilla; a single, vertical, dorsally expanded and rounded humeral spot; 36-39 pored scales in the longitudinal series; body depth 31.6-37.9% SL; anal-fin base length 24.8-30.1% SL; number of branched anal-fin rays 19-22, and bony hooks on pelvic- and anal-fin rays of sexually dimorphic males. The new species is syntopic with other Stervadiinae in the upper rio Paraná basin such as B. iheringii, B. turiuba, Piabarchus stramineus, and Piabina argentea.(AU)

Bryconamericus é o gênero de Stevardiinae mais diverso, com 64 espécies válidas distribuídas nas bacias Cis- e Trans-Andinas, do Panamá na América Central à região norte da Argentina na América do Sul. Dessas espécies, três são conhecidas da bacia do alto rio Paraná: B. exodon, B. iheringii e B. turiuba. Neste trabalho descrevemos uma espécie nova de Bryconamericus da bacia do alto rio Paraná, habitando tributários das bacias dos rios Ivaí, Piquiri e Tibagi, Estado do Paraná, Brasil. A espécie nova difere dos seus congêneres pela presença de dentes desalinhados na fileira externa de dentes do pré-maxilar; uma única mancha umeral vertical, expandida e arredondada dorsalmente; 36-39 escamas perfuradas na série longitudinal; altura do corpo 31,6-37,9% CP; base da nadadeira anal 24,8-30,1% CP; 19-22 raios ramificados na nadadeira anal e ganchos ósseos nas nadadeiras pélvica e anal de machos sexualmente dimórficos. A espécie nova é sintópica com outros Stervadiinae na bacia do alto rio Paraná, como B. iheringii, B. turiuba, Piabarchus stramineus e Piabina argentea.(AU)

Evidence of incipient speciation in astyanax scabripinnis species complex (teleostei: characidae)

Two populations of the Astyanax scabripinnis complex, isolated by a waterfall with over 100 meters depth and inhabiting different altitudes of the same river (1850 m a.s.l. and 662 m a.s.l.) were compared in reproductive data, geometric morphometry, tooth morphology, anal-fin rays counts, and karyotype, in order to test the hypothesis of speciation between the two populations. The results in the geometric morphometry analysis showed differences between the populations. Discriminant function analysis (DFA) and canonical variance analysis revealed sexual dimorphism. Secondary sexual characters, such as hooks in the anal fin rays of the males are absent in the lower altitude population. Both populations had the same macro karyotype structure, except for the absence of B chromosomes in the lower altitude population. The fluorescence in situ hybridization showed differences for both markers (18S rDNA and 5S rDNA), and reproductive data suggests pre-zygotic reproductive isolation among the two populations. The data showed the absence of gene flow, indicating that an incipient speciation process has occurred, which leads the two populations to follow independent evolutionary pathways.

Duas populações do complexo Astyanax scabripinnis isoladas por uma queda d´água de mais de 100 metros de altura e localizadas em diferentes altitudes do mesmo rio (662 m e 1850 m a.s.l.) foram comparadas através de dados de reprodução, cariótipo, morfometria geométrica, morfologia dentária, e número de raios da nadadeira anal, de modo a testar a hipótese de especiação entre as duas populações. Os resultados de morfometria geométrica mostraram diferenças entre as populações. A análise da função discriminante (DFA) e a análise de variância canônica (CVA) demonstraram a presença de dimorfismo sexual. Caracteres sexuais secundários, como ganchos em raios da nadadeira anal dos machos, estão ausentes na população de menor altitude. Ambas as populações têm a mesma macro estrutura cariotípica, exceto pela ausência de cromossomos B na população de menor altitude. A hibridação in situ mostrou diferenças para ambos os marcadores (rDNA 18S e rDNA 5S), e os dados de reprodução sugerem isolamento reprodutivo pré-zigótico entre as duas populações. Os dados mostram ausência de fluxo gênico, indicando que ocorreu um processo de especiação incipiente, o que leva as duas populações seguirem vias evolutivas independentes.

Morphology of the gas bladder in bumblebee catfishes (Siluriformes, Pseudopimelodidae).

The gross morphology of the gas bladder is described and compared for representatives of all valid genera of Pseudopimelodidae (Siluriformes). Cephalosilurus albomarginatus and species of Batrochoglanis, and Microglanis have the most basic form: a large, cordiform gas bladder with a simple internal T-shaped septum. Cephalosilurus apurensis, C. fowleri, and C. nigricauda also have a large, cordiform gas bladder, but they have well-developed trabeculae associated with the internal T-shaped septum, and a pair of well-developed constrictor muscles inserted on the external wall; the latter feature is present in most species of Pimelodidae, but absent in all other catfishes. The monotypic Lophiosilurus alexandri also has well-developed constrictor muscles, and its gas bladder is moderately sized. The species of Pseudopimelodus and Cruciglanis have a diminutive gas bladder partially divided into two lateral sacs without internal communication, and lack constrictor muscles. The parapophysis of the fourth vertebra is a wide and long shelf connected to the dorsal surface of the gas bladder in most pseudopimelodid genera. However, in the species of Pseudopimelodus and Cruciglanis the parapophysis of the fourth vertebra is shorter and has its anterior ramus folded back, partially covering the gas bladder anteroventrally; and the tympanic opening is smaller than in species of the other genera. Five phylogenetic characters are proposed based on the morphology of the gas bladder and associated structures in species of Pseudopimelodidae, and the evolution of those characters in the family is discussed. J. Morphol., 2011. © 2011 Wiley-Liss, Inc.

Genetic variability in four samples of Neoplecostomus yapo (Teleostei: Loricariidae) from the rio Paranapanema basin, Brazil

Four samples of Neoplecostomus yapo were analyzed through the allozyme electrophoresis technique in corn starch gel. The allozyme pattern was similar to those found in N. paranensis with 24 loci scored. Two samples (ribeirão Atlântico and ribeirão Uraí) showed monomorphic bands for all 24 loci, whereas the other two (rio Verde and rio Fortaleza) showed 8.3 percent of polymorphic loci. The He genetic variability estimates for the rios Verde and Fortaleza populations were 0.0195 and 0.0179, respectively, too much inferior to the mean heterozygosity summed to species from the whole world (0.051). The Wright statistical values F IS = 0.5181, F IT = 0.5681 and F ST = 0.1039 and the genetic distance of Nei values showed that the four samples are genetically very similar to each other and that there is homozygote excess in the polymorphic loci.(AU)

Foram analisadas quatro populações de Neoplecostomus yapo por meio da técnica de eletroforese de aloenzimas em gel de amido de milho. O padrão de bandas obtido foi semelhante ao de N. paranensis, tendo sido detectado um total de 24 loci enzimáticos. Duas populações (ribeirão Atlântico e ribeirão Uraí) apresentaram formas monomórficas para todos os 24 loci, enquanto as outras duas (rio Verde e rio Fortaleza) apresentaram 8,3 por cento de loci polimórficos. As estimativas de variabilidade genética He para as populações dos rios Verde e Fortaleza foram 0,0195 e 0,0179, respectivamente, muito inferiores à média das espécies de peixes no mundo todo (0,051). Os valores das estatísticas de Wright F IS = 0,5181, F IT = 0,5681 e F ST = 0,1039 e os valores de distância genética de Nei mostram que as quatro populações são geneticamente muito semelhantes entre si e que há excesso de homozigotos nos loci polimórficos.(AU)

Microglanis carlae, a new species of bumblebee catfish (Siluriformes: Pseudopimelodidae) from the río Paraguay basin in Paraguay

Microglanis carlae, new species, is described from the río Paraguay basin and distinguished from its congeners by the following combination of characters: paired and anal fins mottled or with thin faint bands, trunk with dark-brown saddles, anterior margin of pectoral spine with serrations retrorse proximally and antrorse distally, tip of pectoral spine as a distinct bony point, continuous portion of lateral line reaching vertical through last dorsal-fin ray, caudal peduncle with irregularly shaped, faint to dark blotch, maxillary barbel surpassing vertical through dorsal-spine origin, and dark bar on posterior flank continuous from base of adipose fin to that of anal fin. The new species is included in the Microglanis parahybae species complex on the basis of color pattern.

Microglanis carlae, espécie nova, é descrita da bacia do rio Paraguai e distinguida de todas as congêneres pela seguinte combinação de caracteres: nadadeira anal e nadadeiras pares pigmentadas ou com faixas estreitas, corpo com manchas ou faixas escuras, margem anterior do espinho peitoral com serras retrorsas proximalmente e antrorsas distalmente, espinho peitoral terminando numa ponta, parte contínua da linha lateral atingindo a vertical que passa pelo último raio da nadadeira dorsal, pedúnculo caudal com uma mancha tênue a escura de forma irregular, barbilhão maxilar ultrapassando a vertical que passa pela origem do espinho da nadadeira dorsal, e uma barra escura contínua da base da nadadeira adiposa até a anal. A nova espécie é incluída no complexo de espécies Microglanis parahybae com base no padrão de colorido.

A new species of Hypostomus Lacépède, 1803 (Siluriformes: Loricariidae) from the upper rio Paraná basin, Southern Brazil

A new species of Hypostomus with large and spaced light roundish spots is described from the upper rio Paraná basin. Hypostomus multidens new species is distinguished from all remaining congeners with light spots on a darker background by two independent characters: the presence of teeth with two symmetrical cusps, and a high tooth number in each dentary (122267, mean 196.8) and premaxilla (115-260, mean 190.8)

Uma nova espécie de Hypostomus com pintas claras grandes e espaçadas é descrita para a bacia do alto rio Paraná. Hypostomus multidens nova espécie distingue-se de todas as outras congêneres com pintas claras em um fundo escuro por duas características independentes: a presença de dentes com cúspides simétricas, e um elevado número de dentes em cada dentário (122-267, média 196.8) e pré-maxilar (115-260, média 190.8)