The monotypic genus Carlastyanax Géry was defined to include Astyanax aurocaudatus, a morphologically odd species having, among other features, four teeth in the posterior premaxillary row and eight branched dorsal-fin rays. Later on, the characters used to define Carlastyanax were considered as invalid and this genus was synonymized with Astyanax. In this paper, we include Astyanax aurocaudatus in a phylogeny of the Characidae and obtain a sister-group relationship between this species and Creagrutus, within the Stevardiinae. The resurrection of Carlastyanax as a valid genus is therefore proposed. The analysis presented is the largest phylogeny of the Stevardiinae so far published. Relationships of this subfamily are also discussed.

Cytogenetic analyses were performed on fishes of the genus Hypostomus (Hypostomus ancistroides (Ihering, 1911), Hypostomus strigaticeps (Regan, 1908), Hypostomus regani (Ihering, 1905), and Hypostomus paulinus (Ihering, 1905)) from the seven tributaries of the Paranapanema River Basin (Brazil) by means of different staining techniques (C-, Ag-, CMA3- and DAPI-banding) and fluorescence in situ hybridization (FISH) to detect 18S rDNA sites. All species showed different diploid numbers: 2n=68 (10m+26sm+32st-a) in Hypostomus ancistroides, 2n=72 (10m+16sm+46st-a) in Hypostomus strigaticeps, 2n=72 (10m+18sm+44st-a) in Hypostomus regani and 2n=76 (6m+16sm+54st-a) in Hypostomus paulinus. Ag-staining and FISH revealed various numbers and locations of NORs in the group. NORs were usually located terminally on the subtelocentric/acrocentric chromosomes: on the long arm in Hypostomus strigaticeps (2 to 4) and Hypostomus paulinus (2); and on the short arm in Hypostomus ancistroides (2 to 8) and Hypostomus regani (2 to 4). Conspicuous differences in heterochromatin distribution and composition were found among the species, terminally located in some st-a chromosomes in Hypostomus ancistroides, Hypostomus strigaticeps, and Hypostomus paulinus, and interstitially dispersed in most st-a chromosomes, in Hypostomus regani. The fluorochrome staining indicated that different classes of GC and/or AT-rich repetitive DNA evolved in this group. Our results indicate that chromosomal rearrangements and heterochromatin base-pair composition were significant events during the course of differentiation of this group. These features emerge as an excellent cytotaxonomic marker, providing a better understanding of the evolutionary mechanisms underlying the chromosomal diversity in Hypostomus species.

Hemigrammus tocantinsi is described from the upper rio Tocantins basin, Chapada dos Veadeiros, Goiás State, Central Brazil. The new species differs from its congeners by the presence of 15-17 branched anal-fin rays, longitudinal stripe relatively narrow anteriorly and wider posteriorly, and one or two maxillary teeth. Sexual dimorphism of the new species is characterized by differences among the color in life, adipose-fin origin, body measurements, in addition to presence of bony hooks in the anal and pelvic fins of males.Hemigrammus tocantinsi é descrito da bacia do alto rio Tocantins, Chapada dos Veadeiros, Goiás, Brasil Central. A espécie nova difere de seus congêneres por apresentar 15-17 raios ramificados da nadadeira anal, faixa longitudinal relativamente estreita anteriormente e ampla posteriormente e um ou dois dentes no maxilar. O dimorfismo sexual da nova espécie é caracterizado por diferenças no colorido em vida, origem da nadadeira adiposa, medidas corporais, além de ganchos nas nadadeiras anal e pélvica dos machos.

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 (122-267, 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).

The pseudotympanum, a reduction of the hypaxialis muscle in the body wall lateral to the anterior portion of the swim bladder, is unique to some members of the Otophysi, the largest clade of primarily freshwater fishes. Prior studies documented the presence of the pseudotympanum in a number of groups within the Characiformes, to a lesser extent in subunits of the Siluriformes, and in a few taxa of the Cypriniformes, but with only one record of the aperture in the Gymnotiformes -the Neotropical electric fishes. Surveys across the five families and c. twothirds of the genera in the Gymnotiformes revealed the occurrence of a pseudotympanum in all examined taxa. Pronounced variation in the expanse and details of the morphology of the opening and its relationship to the anterior elements of the axial skeleton was documented amongst Neotropical electric fish. Details of pseudotympanal morphology in the different families of the Gymnotiformes are described and the variation evaluated within the context of the two alternative hypotheses of higher-level phylogenetic relationships within the order.

Serrapinnus potiguar, new species, is described from the rio Ceará-Mirim, a coastal drainage in the Rio Grande do Norte State, northeastern Brazil. The new species is distinguished from the other species of the genus by the shape and arrangement of the ventral procurrent caudal-fin rays of the sexually dimorphic males; where the hypertrophied elements present the shape of a series of scimitars arranged radially, forming a semi-circle on the ventral margin of the caudal peduncle. Furthermore, the new species is diagnosed from S. heterodon and S. piaba, sympatric congeners from the northeastern Brazilian drainages, respectively by the presence of incomplete lateral line and teeth bearing at most five cusps.Serrapinnus potiguar, espécie nova, é descrita para o rio Ceará-Mirim, uma drenagem costeira localizada no estado do Rio Grande do Norte, na região Nordeste do Brasil. A espécie nova distingue-se das demais espécies do gênero pela forma e arranjo dos raios procorrentes ventrais da nadadeira caudal nos machos sexualmente dimórficos; onde os elementos hipertrofiados possuem o formato de uma série de cimitarras arranjados radialmente na margem ventral do pedúnculo caudal, formando um semicírculo. Adicionalmente, a nova espécie diferencia-se de S. heterodon e S. piaba, congêneres simpátricos para as drenagens do Nordeste brasileiro, respectivamente pela presença de linha lateral incompleta e dentes com no máximo cinco cúspides.

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Moenkhausia dasalmas is described from the upper rio Tocantins basin, in the Chapada dos Veadeiros region, Goiás State, Central Brazil. The new species differs from all congeners by the presence of iii,9 rays in the dorsal fin. It can also be distinguished from its congeners by the presence of two humeral spots (first one vertically elongate and second one faint), by the number of branched anal-fin rays (17-19), lateral line scales (36-37), maxillary teeth (4-5), and a vertical dark spot in the caudal peduncle end.Moenkhausia dasalmas é descrita da bacia do alto rio Tocantins, Chapada dos Veadeiros, Goiás, Brasil Central. A espécie nova difere de todas as suas congêneres pela presença de iii,9 raios na nadadeira dorsal. Ela também se distingue das suas congêneres por apresentar duas manchas umerais (a primeira verticalmente alongada e a segunda tênue), 17-19 raios ramificados na nadadeira anal, 36-37 escamas na linha lateral, quatro a cinco dentes no maxilar e uma mancha vertical e escura no final do pedúnculo caudal.