A new species of Panaqolus (Siluriformes: Loricariidae) from the rio Madeira basin with remarkable intraspecific color variation

The rio Madeira is the largest white-water tributary of the Amazon, and is currently the river drainage with the highest fish species diversity in the world. A new species of Panaqolus was recognized from the middle Madeira and Mamoré rivers (Brazil) and from the Madre de Dios drainage (Peru) and it is described herein. This new species is readily distinguished from its congeners by the large number of white dots distributed all over the body and by its remarkable amplitude of color pattern variation, ranging from a pale, light brown, to dark brown and almost black background coloration. The new species closely resembles P. albomaculatus but has more and smaller dots on the body, a smaller orbital diameter (12.5-16.8% head length vs. 16.0-20.0%) and longer maxillary barbels (9.7-19.6% head length vs. 1.6-8.9%). The new species is the second of the genus Panaqolus described for a Brazilian location after nearly 80 years of the description of P. purusiensis. © 2015, Sociedade Brasileira de Ictiologia

Three new species of the armored catfish genus Loricaria (Siluriformes: Loricariidae) from river channels of the Amazon basin

Three new species of Loricaria are described from large white- and black-water river channels of the Amazon basin of Brazil, the upper rio Negro drainage of southern Venezuela, and clear waters of the lower rio Tocantins. Loricaria spinulifera and L. pumila differ from other species of Loricaria by having unique patterns of abdominal plate development and hypertrophied odontodes forming conspicuous crests on dorsal surfaces of the head and predorsal plates. Both are small species of Loricaria, reaching sexual maturity at less than 120 mm SL, and exhibiting sexually dimorphic characters consistent with members of the L. cataphracta complex. Loricaria spinulifera differs from L. pumila in having a unique arrangement of buccal papillae and large thorn-like odontodes on the dorsum of the head. Loricaria pumila is the smallest known Loricaria, reaching sexual maturity at less than 80 mm SL. Loricaria lundbergi differs from other Loricaria by having a unique abdominal plate pattern, broad head, and small basicaudal plate. Loricaria lundbergi is sympatric with L. spinulifera in the lower rio Negro drainage, but is also known from the rio Baria system of the Casiquiare drainage. Loricaria pumila occurs in the lower rio Amazonas and lower rio Tocantins. All three new species exhibit varying degrees of reduction in eye size and pigmentation seen in other fishes inhabiting deep river channels of South America. Copyright © 2008 Sociedade Brasileira de Ictiologia

Taxonomic revision of Spectracanthicus Nijssen & Isbrücker (Loricariidae: Hypostominae: Ancistrini), with description of three new species

A taxonomic review of Spectracanthicus Nijssen & Isbrücker, including Oligancistrus Rapp Py-Daniel, following a phylogenetic study, is presented. Additionally to S. punctatissimus (Steindachner) and S. murinus Nijssen & Isbrücker, three new species are recognized based on the examination of 159 specimens: S. immaculatus n. sp. from rio Tapajós basin, differs from its congeners by its color pattern consisting of a dark gray body, with no dots or spots, and by having very slender teeth; Spectracanthicus tocantinensis n. sp., from the rio Tocantins drainage is distinguished by the color pattern consisting of dark brown or black body with small, yellowish dots (except in S. punctatissimus), presence of thick teeth, infraorbital 4 forming most of the posterior edge of the orbit and the large basipterigium fenestrae; and Spectracanthicus zuanoni n. sp., from the rio Xingu basin is diagnosed by its color pattern consisting of large, white spots and by the larger orbital diameter. Other characters based on osteological features are also usefull to distinguish the species. A key to the species of the genus and a brief discussion of their threats and conservation are also provided. © 2014 Sociedade Brasileira de Ictiologia

Sexual dimorfism in Amazonian Siluriformes and Gymnotiformes (Ostariophysi)

The present paper aims to summarize cases of sexual dimorphism in Siluriformes and Gymnotiformes. This focuses on Neotropical representatives, with emphasis on Amazonian fish. Fishes from this region exhibit high species-level diversity, although the intraspecific limits of many of these forms are unknown. In Loricariidae (Siluriformes), mapping of dimorphic traits on cladograms has helped to demonstrate that patterns of sex dimorphism are consistent with hypotheses of monophyly, thus reinforcing its role as an important evolutionary phenomenon. In Apteronotidae (Gymnotiformes), mapping of characters on phylogenetic trees suggests that sexual dimorphism (regarding snout size, form, and presence/absence of teeth) has evolved independently in multiple taxa. Recently in Gymnotiformes, detected taxonomic errors are attributed to extreme differences between males and females in their morphology.No presente trabalho é feito um levantamento dos casos de dimorfismo sexual em Siluriformes e Gymnotiformes. Este levantamento se restringe às formas Neotropicais, com ênfase mais especificamente, às da Amazônia. Peixes dessa região possuem uma grande diversidade, ainda que os limites intraespecíficos não estejam bem definidos. Embora preliminar, o mapeamento de características dimórficas em um cladograma referente a família Loricariidae (Siluriformes) auxilia na demonstração de que padrões de dimorfismo sexual são consistentes com hipóteses de monofiletismo. Em Apteronotidae (Gymnotiformes), com base no mapeamento dos caracteres tamanho e forma do focinho e presença de dentes diferenciada em árvores filogenéticas, podemos inferir que esses caracteres originaram-se como eventos independentes em vários táxons. Recentemente, em Gymnotiformes, foram detectados casos de erros taxonômicos atribuídos a diferenças extremas entre machos e fêmeas

Ageneiosus uranophthalmus, a new species of auchenipterid catfish (Osteichthyes: Siluriformes) from river channels of the central Amazon basin, Brazil

Ageneiosus uranophthalmus is described from river channels of the central Amazon basin, Brazil. The new species is widely distributed in the Amazon and is distinguished from its congeners by the V-shape snout and eye laterally placed and dorsally oriented, more visible in dorsal view than in ventral view. Ageneiosus uranophthalmus shows a range of variation on color pattern when compared with its congeners. This and other differences are described and discussed herein. © 2010 Sociedade Brasileira de Ictiologia

Assembleias de peixes de duas praias no baixo rio Purus, Amazonas, Brasil

Fish assemblages from two sandy beaches in the lower Purus river (Amazonas, Brazil) were compared. Four sampling groups were represented by: day and night samples in sandy beach inside the Reserva Biológica de Abufari (biological reserve) and day and night samples in the Reserva de Desenvolvimento Sustentável Piagaçu-Purus (sustainable development reserve). Samples were collected during low water levels (November) in 2007. The fish were sampled by means of seines with mesh size of 5 mm between opposing knots, 11 m long and 6 m wide. A total of 112 fish species belonging to nine orders and 27 families was captured. The vast majority of the dominant forms consisted of small fishes (< 100 mm SL) or juveniles. Samples collected in Abufari at night presented more specimens (3,540), higher richness (84 spp.), larger total biomass (76,614 g) and higher diversity (H'= 2.57) than the other groups. The composition of fish assemblages was significantly different among all analyzed groups (ANOSIM, p < 0.0001, R= 0.71). NMDS analysis also clustered all species in four distinct groups according to species composition per period and site. SIMPER analyses showed that 80% of variation of species composition among the groups examined was due to 12 species. However, fish composition did not show any correlation with the abiotic factors examined. Different levels of use in both reserves may explain differences in fish composition

A new silver dollar species of Metynnis cope, 1878 (Characiformes: Serrasalmidae) from Northwestern Brazil and Southern Venezuela

A new Metynnis is described from the rio Negro in Brazil and Venezuela, and from black- or clearwater tributaries in Brazil including the rios Parauari, Uatumã, Trombetas, and Sucunduri (the latter belonging to the rio Madeira basin). The new species can be distinguished readily from all congeners by having a high concentration of dark chromatophores on the lateral line scales. It can be further distinguished by the combination of head length 24.3-27.5% of SL, 13-18 gill-rakers on upper limb and 16-24 gill-rakers on lower limb. The new species is most similar to and likely most closely related to Metynnis hypsauchen. These two species share a similar color pattern, body shape and sexual dimorphism of the anal fin. However, they differ in that M. hypsauchen has a lightly pigmented lateral line. The new species is also distinguished from M. hypsauchen by having 56-65 predorsal scales and 90-104 lateral line scales (vs. 36-54, and 65-82, respectively). A detailed osteological description of the new species is provided. © 2016, Sociedade Brasileira de Ictiologia. All rights reserved

Comparison of the relative efficiency of two fishing gears in sandy beaches in lower Purus river, Amazonas, Brazil

Despite representing one of the seven most important aquatic habitats in the Amazon, little has been done concerning fish inventories on sandy beaches, especially related to the fishing gear used in these environments. This study aims to compare the relative efficiency of two fishing gears, seine and gill-net, used actively (trawling), on three sandy beaches on the lower reaches of Rio Purus. Seining resulted in a larger number of species and specimens, whereas for total biomass, gill-nets showed larger values, mainly represented by Siluriformes. Low similarity between samples (38%) was due to different catches of each gear: 41 species collected only with seine and 32 only with gill-net. The present study strengthens the importance of using different fishing gears in experimental fisheries as a way to overcome the inherent selectivity of each gear, and thus improving the efficacy of sampling in poorly-known environments.Apesar das praias serem consideradas um dos sete mais importantes habitats aquáticos da Amazônia, poucos trabalhos foram realizados quanto ao levantamento de sua ictiofauna, principalmente quando utilizados diferentes apetrechos de coleta. Este trabalho teve como objetivo comparar a eficiência relativa de dois apetrechos, rede de cerco e malhadeira, ambos utilizados de forma ativa (arrasto), em três praias localizadas no baixo rio Purus. A rede de cerco apresentou maior número de espécies e indivíduos capturados, no entanto, a malhadeira apresentou maiores valores de biomassa total, representada principalmente por Siluriformes. A baixa similaridade da fauna de peixes capturada (38%) foi devido à exclusividade de espécies coletadas com cada apetrecho, 41 com rede de cerco e 32 com malhadeira. O presente trabalho mostra a importância de se utilizar diferentes apetrechos de coleta como forma de diminuir a seletividade inerente de cada um desses aparelhos, melhorando a efetividade de amostragens em ambientes pouco estudados

Two new ornamental loricariid catfishes of Baryancistrus from rio Xingu drainage (Siluriformes: Hypostominae)

Two new species of the hypostomine genus Baryancistrus are described from the rio Xingu drainage. Baryancistrus xanthellus is distinguished from all other Baryancistrus species by the presence of yellow spots along the entire body and conspicuous yellow marks on distal tip of dorsal and caudal fins. Baryancistrus chrysolomus is distinguished from its congeners by its uniform dark body coloration and presence of yellow bands on dorsal and caudal fins. Despite the lack of formal description, these species are very popular in the international aquarium trade. We expect that these formal descriptions might contribute to the improvement of Brazilian regulations in the international trade of ornamental loricariids. © 2011 Sociedade Brasileira de Ictiologia

A new species of Aphanotorulus (Siluriformes: Loricariidae) from the rio Aripuanã Basin, Brazil

The cis-Andean genus Aphanotorulus was recently revised and comprises six valid species: A. ammophilus, A. emarginatus, A. gomesi, A. horridus, A. phrixosoma and A. unicolor. Herein, a new species is described from tributaries of the rio Aripuanã basin, in Amazonas and Mato Grosso states, Brazil. The new species is easily distinguished from congeners by its color pattern: caudal fin with upper lobe mostly hyaline with dark spots along rays and membranes, and lower lobe red and without dark spots; and absence of dark spots in the lateral series of mid-ventral plates. © 2017, Sociedade Brasileira de Ictiologia. All rights reserved