New small-sized species of Astyanax (Characiformes: Characidae) from the upper rio Paraguai basin, Brazil, with discussion on its generic allocation

A new species of Astyanax is described from the rio Salobra, tributary of rio Cuiabá, rio Paraguai basin. The new taxon can be distinguished from its congeners by having a well-defined dark midlateral stripe on body extending from the posterior margin of the opercle to the base of middle caudal-fin rays and a single vertical elongate humeral blotch. Although the new species is described in Astyanax, some specimens present an incomplete or a discontinuous series of perforated scales in the lateral line. Therefore, a discussion on its generic allocation is presented. Comments on different patterns of coloration among dark-striped species of Astyanax are also provided. The discovery of a new species in an underwater tourist point relatively near a large urban center underscores that even fish species daily observed by hundreds of people in limpid waters may lack a formal taxonomic identity. Such finding also highlights how the megadiverse Brazilian freshwater ichthyofauna still needs efforts and investments to identify and describe new taxa.(AU)

Uma nova espécie de Astyanax é descrita do rio Salobra, afluente do rio Cuiabá, bacia do rio Paraguai. O táxon novo pode ser diferenciado de seus congêneres por apresentar uma faixa médio-lateral escura bem definida no corpo, se estendendo da margem posterior do opérculo até a base dos raios medianos da nadadeira caudal e por possuir uma mancha umeral verticalmente alongada. Apesar da espécie nova ser descrita em Astyanax, alguns exemplares apresentam uma série incompleta ou descontínua de escamas perfuradas na linha lateral. Assim, uma discussão sobre sua alocação genérica é apresentada. Comentários sobre os diferentes padrões de coloração de espécies de Astyanax com faixa escura também são fornecidos. A descoberta de uma espécie nova em um ponto turístico subaquático relativamente próximo a um grande centro urbano ressalta que mesmo as espécies de peixes observadas diariamente por centenas de pessoas em águas límpidas podem não ter uma identidade taxonômica formal. Tal achado também evidencia o quanto a megadiversa ictiofauna de água doce brasileira ainda precisa de esforços de coleta adicionais e investimentos para identificar e descrever os táxons novos.(AU)

Effects of Toluene on the Development of the Inner Ear and Lateral Line Sensory System of Zebrafish / 生物医学与环境科学（英文）

Objective@#The aim of this study was to explore the ototoxicity of toluene in the early development of zebrafish embryos/larvae.@*Methods@#Zebrafish were utilized to explore the ototoxicity of toluene. Locomotion analysis, immunofluorescence, and qPCR were used to understand the phenotypes and molecular mechanisms of toluene ototoxicity.@*Results@#The results demonstrated that at 2 mmol/L, toluene induced zebrafish larvae death at 120 hours post fertilization (hpf) at a rate of 25.79% and inhibited the rate of hatching at 72 hpf. Furthermore, toluene exposure inhibited the distance travelled and average swimming velocity of zebrafish larvae while increasing the frequency of movements. As shown by fluorescence staining of hair cells, toluene inhibited the formation of lateral line neuromasts and middle line 1 (Ml @*Conclusion@#This study indicated that toluene may affect the development of both the inner ear and lateral line systems in zebrafish, while the lateral line system may be more sensitive to toluene than the inner ear.

Descripción y comparación de la línea lateral de tres especies de rayas eléctricas del género Narcine (Torpediniformes: Narcinidae) / Description and comparison of the lateral line of three species of electric rays of the genus Narcine (Torpediniformes: Narcinidae)

Resumen Se presenta la descripción de la composición y arreglo estructural del sistema de la línea lateral de tres especies de rayas eléctricas (Narcine bancroftii, N. entemedor y N. vermiculatus). Las tres especies muestran los canales supraorbital (SO), infraorbital (IO), hiomandibular (HYO) y de la línea lateral posterior (LLP), menos ramificados que en otros batoideos. Narcine entemedor difiere de sus congéneres por la gran ramificación de los canales SO e IO, los cuales convergen en la región inter-orbital; en N. vermiculatus estos canales presentan una condición similar, pero con una menor ramificación. En contraste N. bancroftii presenta los canales divergentes (dirigidos hacia afuera de la región inter-orbital). Los canales HYO están localizados en la periferia de los órganos eléctricos en estas especies; en N. bancroftii las ramificaciones se extienden hacia la región posterior, mientras que en las demás especies están reducidas (N. entemedor) o casi ausentes (N. vermiculatus). La LLP es de forma curva y está dirigida hacia el urostilo, asimismo muestra un gran número de ramificaciones, excepto en N. vermiculatus. La información sobre el arreglo y el número de poros sobre el sistema de canales de la LL en Narcine, puede ser de utilidad para la distinción taxonómica de sus especies, tal como ha sido corroborado para otros Torpediniformes.

Abstract This study describes the composition and structural arrangement of the lateral line system of three electric ray species (Narcine bancroftii, N. entemedor and N. vermiculatus). All three species showed the supraorbital (SO), infraorbital (IO), hyomandibular (HYO) and posterior lateral line (PLL) canals, less branched compared to other batoids. Narcine entemedor differs from its congeners by the extensive branching of the SO and IO canals, which converge in the inter-orbital region; in N. vermiculatus these canals present a similar condition, but are less branched. In contrast, N. bancroftii has divergent canals (directed outwards from the inter-orbital region). HYO canals are located on the periphery of the electric organs in these species; in N. bancroftii the branches extend towards the posterior region, whereas in the other species are reduced (N. entemedor) or almost absent (N. vermiculatus). The PLL is curved and projected towards the urostyle, it also shows a large number of ramifications, except in N. vermiculatus. Information about the LL canal system arrangement and pore number in Narcine can be useful for the taxonomic distinction of its species, as it has been corroborated in other Torpediniformes. Rev. Biol. Trop. 66(2): 586-592. Epub 2018 June 01.

A new species of Boehlkea (Characiformes: Characidae: Stevardiinae) from the rio Japurá, Amazon basin, Brazil

A new species of Boehlkea is described from rio Japurá, Amazon basin. The new species differs from B. fredcochui by the presence of a vertically elongate humeral spot (vs. absence), complete lateral line (vs. incomplete), four rows of scales below lateral line (vs. three), and lower number of branched anal-fin rays (17-21 vs. 22-25), and from B. orcesi by the higher number of maxillary teeth (13-14 vs. 5-12), greater head length (27.9-29.9% vs. 24.3-27.5% of SL), and by the color pattern (basal half of dorsal-fin, distal portion of pelvic-fin, lower caudal-fin lobe and anal-fin with black chromatophores vs. absence of black chromatophores in the fins).(AU)

Uma nova espécie de Boehlkea é descrita do rio Japurá, bacia Amazônica. A espécie nova difere de B. fredcochui pela presença de uma mancha umeral verticalmente alongada (vs. ausência), linha lateral completa (vs. incompleta), quatro séries de escamas abaixo da linha lateral (vs. três), e menor número de raios ramificados na nadadeira anal (17-21 vs. 22-25), e de B. orcesi pelo maior número de dentes no maxilar (13-14 vs. 5-12), maior comprimento da cabeça (27,9-29,9% vs. 24,3-27,5% do CP), e pelo padrão de colorido (porção inferior da nadadeira dorsal, porção distal da nadadeira pélvica, lobo inferior das nadadeiras caudal e anal com cromatóforos pretos vs. ausência de cromatóforos pretos nas nadadeiras)(AU)

Hemigrammus ataktos: a new species from the rio Tocantins basin, central Brazil (characiformes: characidae)

A new species of hemigrammus is described from the middle rio Tocantins basin, central Brazil. The new species can be distinguished from all congeners by having a black midlateral stripe on the body extending from the posterior margin of the eye to the median caudal-fin rays. Mature males possess dorsal-, pelvic-, and anal-fin rays elongate, features that also help to recognize the new species. Although the new species is described in Hemigrammus, some specimens present a complete series of pored scales in the lateral line. A discussion about the generic allocation of the new species is presented.

Uma espécie nova de hemigrammus é descrita da bacia do médio rio Tocantins, Brasil central. A espécie nova distingue-se de seus congêneres por apresentar uma faixa mediana negra na lateral do corpo desde a margem posterior do olho até os raios medianos da nadadeira caudal. Machos maduros apresentam os raios das nadadeiras dorsal, pélvica e anal alongados, características que também auxiliam o reconhecimento da espécie. Apesar da espécie nova ser descrita em Hemigrammus, alguns exemplares possuem série completa de escamas perfuradas na linha lateral. Uma discussão sobre o posicionamento genérico da espécie nova é apresentada.

The Zebrafish Model for the Study on Hair Cell Development / 听力学及言语疾病杂志

Objective This study aims to examine the development of the posterior lateral line of the zebrafish and establish ant model to study the process of hair cell differentiation and regeneration .Methods We observed the posterior lateral line system formation by DAPI immunohistochemistry and whole mount in situ hybridization .We further evaluated hair cells differentiation within neuromast by using Transgenic Tg (Brn3c:mGFP) zebrafish and stained the functional hair cells by the mechanotransduction marker FM 1 -43FX .We labelled proliferating cells in primordium and neuromast by addition of BrdU to the system water .Results The posterior lateral line primordium originated from a sensory placode and started its journey at around 20 hours post fertilization to migrate along the horizontal myoseptum to the tail -tip with a constant speed (1 .7somite/hour) .The primordium depositd five or six neuromasts spaced along the body ,and two or three terminal neuromasts at the tail -tip at 48 hours post fertiliza-tion .At 3 ,5 and 7 days post fertilization ,zebrafish contained 5 .68 ± 1 .46 ,10 .1 ± 0 .99 ,and 12 .45 ± 1 .32 hair cells per neuromast ,respectively .Furthermore ,the average number of FM1-43FX stained hair cells within each neuro-mast were 3 .68 ± 1 .11 ,8 .18 ± 1 .86 ,and 10 .22 ± 1 .24 ,respectively .Conclusion We establish the development model of hair cells in zebrafish lateral line neuromast and suggest that 3 to 7 days post fertilization is an important period for lateral line neuromast differentiation .This study would be useful for underlying the mechanisms of hair cell differentiation and regeneration .