Search

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. Resumo 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.

The rapids-dwelling suckermouth catfish genus Pseudolithoxus was previously only known from the Guiana-Shield-draining Orinoco and Casiquiare river systems of Colombia and Venezuela, but new records have expanded this range considerably further into the Amazon basin of Brazil, and include occurrences from rivers draining the northern Brazilian Shield. These highly disjunct records are now placed in an evolutionary and phylogeographic context using a dated species tree constructed from mitochondrial (Cytb) and nuclear (RAG1) gene sequence data. Due to mito-nuclear discordance, we also delimit the putative species using statistical coalescent models and a range of additional metrics. We infer that at least two species of Pseudolithoxus are present in the Amazon basin: P. nicoi, previously only recorded from the río Casiquiare, but now also reported from the upper rio Negro, and a new species, which we describe herein from south-draining Guiana Shield and north-draining Brazilian Shield. Our data reject a simple model of Miocene vicariance in the group following uplift of the Uaupés Arch separating the Orinoco and Amazon systems, and instead suggest more complex dispersal scenarios through palaeo-connections in the Pliocene and also via the contemporary rio Negro and rio Madeira in the late Pleistocene. www.zoobank.org/urn:lsid:zoobank.org:pub:46A6BEC1-1A1B-4244-80-A6-FD9CF8DA0384.

In the midst of the effervescent discussions of climate change and setbacks in national environmental protection mechanisms, the Brazilian Amazon and its ichthyofauna are in the spotlight. Therefore, in this work we redescribe Hypostomus carinatus (Steindachner 1881), a little known medium-sized Amazonian species, providing means for its correct identification and taxonomic stabilization. In this way, based on the analysis of type specimens and recently collected material, H. carinatus is redescribed and its geographical distribution is expanded to the basins of the Branco, Japurá, Juruá, Solimões, Negro, Tapajós, Trombetas and Uatumã rivers. A lectotype of the Plecostomus carinatus is designated herein. Hypostomus carinatus is mainly distinguished from congeners by the presence of four to ten predorsal plates posteriorly surrounding parieto-supraoccipital bone; dark spots on body and fins; by having the dark spots smaller or almost equal to distance among each spot; body carenae armored with odontodes; and compressed head with eyes laterally positioned.

A new species of Hypostomus with spoon-shaped teeth is described from the Rio Cupari basin, a right margin affluent of the lower Rio Tapajos, Para 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.

Is there only one electric eel species? For two and a half centuries since its description by Linnaeus, Electrophorus electricus has captivated humankind by its capacity to generate strong electric discharges. Despite the importance of Electrophorus in multiple fields of science, the possibility of additional species-level diversity in the genus, which could also reveal a hidden variety of substances and bioelectrogenic functions, has hitherto not been explored. Here, based on overwhelming patterns of genetic, morphological, and ecological data, we reject the hypothesis of a single species broadly distributed throughout Greater Amazonia. Our analyses readily identify three major lineages that diverged during the Miocene and Pliocene—two of which warrant recognition as new species. For one of the new species, we recorded a discharge of 860 V, well above 650 V previously cited for Electrophorus, making it the strongest living bioelectricity generator., A single species of electric eel, Electrophorus electricus, has been described. Here, de Santana et al. show that there are three major lineages of Electrophorus distributed across Greater Amazonia and describe two new species, one with a much stronger electric discharge than was previously known.

Two new species of the suckermouth armored catfish genus Baryancistrus are described from the Jari River basin, at the border of Para and Amapa states, Brazil. The new species are the first representatives of the genus described from rivers draining the Guiana shield, and can be distinguished from their congeners by color pattern and a combination of nonexclusive characters. Baryancistrus micropunctatus, new species, has a color pattern similar to B. longipinnis from the Tocantins River, whereas Baryancistrus hadrostomus, new species, has a color pattern that is unique for the genus, with a gray to black body covered by small and widely spaced white points. The first exemplars of the two new species were collected in the late 1980s by INPA ichthyological staff, and in 2007 additional materials were collected by the Museu de Zoologia da Universidade de Sao Paulo (MZUSP), providing a foundation for this description of the new species.

Peckoltia is one of the 26 genera that constitute the Ancistrini. Although Peckoltia has been reviewed recently, its taxonomic status is not fully resolved and not easily distinguished from Hemiancistrus. Neither Peckoltia nor Hemiancistrus have any recognized synapomorphies supporting their monophyly. In this paper we describe a new species of Ancistrini from Rio Xingu drainage, Para State, Brazil, and assign it to Peckoltia based on its deep body, presence of large odontodes on the cheeks, and lack of carenate plates on the body. The new species can be easily distinguished from all its congeners by its dorsal-fin color pattern (presence of dark thin stripes in the interradial membranes parallel to fin rays that fragment into small spots in larger specimens vs. bands, spots, dots, or membranes with a darker coloration in all other species). Peckoltia feldbergae, new species, differs from all its congeners except P. bachi, P. oligospila, and P. sabaji by having dark brown spots on the entire body (vs. pre...

Hypostomus delimaiis described from the rio Tocantins, Tocantins State, and from the rio Araguaia, Pará, and Tocantins States, Brazil. The new species is distinguished from all other Hypostomusspecies, except from H. carinatus, H. hoplonites, and H. watwata, by the presence of five to eight (mode seven) predorsal plates limiting posterior border of the supraoccipital bone (vs. one to three plates). It can be distinguished from H. carinatus, H. hoplonites, and H. watwata by having pale spots over darker background on body and fins (vs. dark spots over lighter background). The species was only found in the middle stretches of the rio Tocantins-Araguaia basin. The first collection of specimens assigned to the new species was done in the rio Tocantins before the construction of the Tucuruí dam. Recently additional material was collected in the rio Araguaia, in a habitat that soon will be flooded for the construction of the Santa Isabel hydroelectric power station. Hypostomus delimai é descrita do rio Tocantins no estado do Tocantins e do rio Araguaia, entre os estados do Pará e Tocantins, Brasil. A espécie nova é diagnosticada das demais espécies de Hypostomus, com exceção de H. carinatus, H. hoplonites e H. watwata por possuir de cinco a oito (moda sete) placas pré-dorsais margeando a borda posterior do supraoccipital (vs.uma ou até três placas). Difere de H. carinatus, H. hoplonites, e H. watwata por apresentar pintas claras sobre o corpo e nadadeiras (vs. pintas escuras sobre fundo claro). A espécie nova foi encontrada somente no trecho médio da bacia do rio Tocantins-Araguaia. Os primeiros registros da espécie nova foram feitos no rio Tocantins antes da construção da barragem de Tucuruí. Recentemente, material adicional foi coletado no rio Araguaia, em um habitat que será brevemente inundado pela construção da hidrelétrica de Santa Isabel.

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. Duas espécies novas de hipostomíneos do gênero Baryancistrus são descritas da bacia do rio Xingu. Baryancistrus xanthellus se diferencia de todas as outras espécies de Baryancistrus pela presença de pontos amarelos em todo o corpo e presença de manchas conspícuas amarelas nas pontas das nadadeiras dorsal e caudal. Baryancistrus chrysolomus se distingue de seus congêneres pela sua coloração escura uniforme e presença de uma faixa amarela nas nadadeiras dorsal e caudal. Apesar de não estarem formalmente descritos, esses peixes são muito populares no comércio aquariofilista internacional. Esperamos que essas descrições formais contribuam para melhorar a regulamentação brasileira no comércio internacional de loricariídeos ornamentais.

The loricariid genus Peckoltia currently encompasses 13 valid species ranging throughout the Amazon basin in Brazil, Venezuela, Colombia, Peru, and Guyanas. Peckoltia is included in the tribe Ancistrini, but its relationships with other taxa within the tribe are not well established. In this paper we describe a new species of Peckoltia from the rio Tapajos drainage, Para State, Brazil. Peckoltia compta, new species, is characterized by a bold color pattern consisting of large dark transversal bars on body and thick longitudinal dark stripes on snout and head. The new species is most similar in color pattern to P. vittata but can be distinguished from all its congeners by the presence of a pale line inside each dark stripe running from the snout tip to anterior margin of eyes (vs. absence of such clear lines and a mottled appearance in P. vittata, and a mix of vermiculations and spots on the head of the remaining congeners). A brief discussion on the taxonomic status of the nominal species Peckoltia vittata is also presented.

This study was conducted in an Amazonas state conservation unit, the Catuá-Ipixuna Extractive Reserve (Catuá-Ipixuna RESEX). The main purpose was to provide an ichthyological survey of its small streams, all them tributaries of the Solimões River. Nine small streams (up to 4 m width and 1 m depth) were sampled in September 2006. A total of 1,525 specimens were captured, belonging to 78 species, 24 families and eight orders. Eight species had higher abundances and represented altogether 61.4 % of all collected specimens (Hemigrammus belotii, Microphilypnus amazonicus, Physopyxis ananas, Apistogramma agassizii, Elachocharax pulcher, Apistogramma cf. cruzi, Gladioglanis conquistador and Copella nigrofasciata). Based on the high number of singletons and doubletons present in our samples, as well as the estimated number of species for those streams (106 spp.), we believe that the total fish species richness present in the Catuá-Ipixuna Extractive Reserve may be considerably higher than indicated by our samples. This seems especially true when considering the dimensions of the Catuá-Ipixuna RESEX and the dense hydrographic network present in the area.

A new species of Scoloplax is described from small tributaries of rio Aripuanã, rio Madeira drainage, Amazonas State, Brazil. The new species can be distinguished from its congeners by several morphological features, such as ventral midline plates with two longitudinal parallel rows of odontodes not covered by skin, pectoral and pelvic fins with all rays simple, unbranched, and mesethmoid with a thickened triangular anterior process. Implications of new records of S. dolicholophia from rio Japurá and other comparative features within the genus are discussed. Uma nova espécie de Scoloplax é descrita para pequenos tributários do rio Aripuanã, drenagem do rio Madeira, estado do Amazonas, Brasil. A nova espécie pode ser diferenciada das demais espécies do gênero por vários aspectos morfológicos, tais como placas ventrais da linha média apresentando duas fileiras paralelas de odontódeos não cobertos por pele, nadadeiras peitoral e pélvica com todos os raios simples, não ramificados, e mesetmóide com um espessamento no processo anterior. Implicações dos novos registros de S. dolicholophia do rio Japurá e outros aspectos comparativos do gênero são discutidos.

A new species of Gladioglanis is described from a single locality on rio Aripuanã, rio Madeira basin, and can be distinguished from its congeners by the following characters: dorsal-fin spine and spinelet absent, first dorsal-fin ray flexible, unbranched, followed by five branched dorsal-fin rays, pectoral-fin spine short and with few (5 anterior-side, 4 posterior-side) dentations, 22-25 anal-fin rays, round profile of the head in dorsal view, first dorsal-fin pterygiophore in contact with the neural spine of eighth vertebrae, 13 caudal-fin rays in both upper and lower lobes, and 60 total vertebrae. Some of its characters are discussed below and compared among the species of a small clade within Heptapteridae proposed by Bockmann (1998). Uma nova espécie de Gladioglanis é descrita de uma única localidade no rio Aripuanã, bacia do rio Madeira, e pode ser diferenciada de seus congêneres pelos seguintes caracteres: espinho dorsal e trava do espinho ausentes, primeiro raio da dorsal simples, flexível, seguido de cinco raios ramificados na nadadeira dorsal, espinho peitoral menor e com poucas (5 anteriores e 4 posteriores) serras, 22-25 raios na nadadeira anal, perfil da cabeça arredondado em vista dorsal, primeiro pterigióforo da nadadeira dorsal em contato com o espinho neural da oitava vértebra, 13 raios na nadadeira caudal em ambos lobos superior e inferior, e 60 vértebras. Alguns dos caracteres são discutidos e comparados entre as espécies de um pequeno clado dentro de Heptapteridae proposto por Bockmann (1998).

A new species of Propimelodus from the middle course of the rio Araguaia is described. Propimelodus araguayae, new species, can be distinguished from its congeners in having a conspicuous black dot on the base of the dorsal-fin rays (vs. a different pattern), large eyes (29.7-34.8% of head length and 62.7-74.7% of snout length vs. 14.5-21.1% and 31-44% in P. caesius and 9.5-19.7% and 17-38% in P. eigenmanni), anal-fin lobe present (vs. absent), premaxillary bone with three irregular rows of teeth (vs. 4-5 in P. caesius and 5-8 in P. eigenmanni), tip of anterior lateral process of basipterygium at the same level as the tip of the anterior medial process (vs. anterior lateral process extending beyond the tip of the anterior medial process), total number of vertebrae (43-44 vs. 47-48 in P. caesius and 45-46 in P. eigenmanni) and total number of gill rakers (28-33 vs. 20-23 in P. caesius and 19-20 in P. eigenmanni). This new species is possibly endemic to the middle course of the rio Araguaia. Uma nova espécie de Propimelodus do trecho médio do rio Araguaia é descrita. Propimelodus araguayae, nova espécie, pode ser distinguida de suas congêneres pela presença de uma conspícua mancha preta na base dos raios da nadadeira dorsal (vs. um padrão distinto), olhos grandes (29,7-34,8% do comprimento da cabeça e 62,7-74,7% do comprimento do focinho vs. 14,5-21,1% e 31-44% em P. caesius e 9,5-19,7% e 17-38% em P. eigenmanni), presença de um lobo na nadadeira anal (vs. ausente), premaxilar com três fileiras irregulares de dentes (vs. 4-5 em P. caesius e 5-8 em P. eigenmanni), extremidade do processo medial anterior do basipterigio na mesma transversal que passa na extremidade do processo lateral anterior (vs. extremidade do processo medial anterior do basipterigio não atingindo a transversal que passa pela extremidade do processo lateral anterior), menor número total de vértebras (43-44 vs. 47-48 em P. caesius e 45-46 em P. eigenmanni) e maior número de rastros branquiais no primeiro arco (28-33 vs. 20-23 em P. caesius e 19-20 em P. eigenmanni). Esta nova espécie é possivelmente endêmica ao curso médio do rio Araguaia.

Loricariid catfishes show a predominance of homomorphism in sex chromosomes, but cases of simple and multiple systems were also found. Here we describe two cases of multiple sex chromosome systems in loricariids from Brazilian Amazonia. Males of Ancistrus sp.1 "Balbina" have a modal number of 2n = 39 chromosomes, fundamental number (FN) of 78, and karyotypic formula of 27 m + 10 sm + 2 st; females have 2n = 38 chromosomes, FN = 76, and 26 m + 10 sm + 2 st. Ancistrus sp.2 "Barcelos" has 2n = 52 chromosomes for both sexes, FN = 80 for males and FN = 79 for females. Karyotypic formula is 12 m + 12 sm + 4 st + 24a for males and 11 m + 12 sm + 4st + 25a for females. The two species show different arrangements of constitutive heterochromatin blocks, which are coincident with NORs and absent in sex chromosomes. We suggest a XX/XY(1)Y(2) mechanism for Ancistrus sp.1 "Balbina", and a Z(1)Z(1)Z(2)Z(2)/Z(1)Z(2)W(1)W(2) mechanism for Ancistrus sp.2 "Barcelos". The XX/XY(1)Y(2) mechanism here reported is the second known occurrence of this type of multiple sex chromosomes for Loricariidae and the third for Neotropical fishes; the mechanism Z(1)Z(1)Z(2)Z(2)/Z(1)Z(2)W(1)W(2) represents the first record among fishes. The presence of different sex chromosome systems in Ancistrus indicates a probable independent origin and suggests that the differentiation of sex chromosomes is evolutionarily recent among species in this genus.

The neotropical freshwater systems have a high number of catfish species (Siluriformes), and many of those are denominated "cascudos" in Brazil. Cytogenetic data about three "cascudos" species fished in the rio Araguaia are described in the present study. The Pterygoplichthys joselimaianus showed 2n=52, with 28 metacentrics (M) chromosomes, 16 submetacentrics (SM) and 8 subtelocentrics/acrocentrics (ST/A) in both sexes. Hemiancistrus spinosissimus showed 2n=52, with karyotype formulae 26M+22SM+4ST, in both sexes. Hemiancistrusspilomma also showed 2n=52, but in this species a ZZ/ZW sex chromosome system (25M+21SM+6ST in females and 24M+22SM+6ST in males) was observed. The cells from H. spinosissimus and P. joselimaianus showed one chromosome pair bearing Ag-NORs, while in the H. spilomma three chromosome pairs bearing Ag-NORs were detected. The data showed in this work reveal particular chromosomal characteristics, important for a good recognition of both Hemincistrus species, and also show the importance of the insertion of cytogenetic data on taxonomic phylogenetic studies. Os sistemas deágua doce neotropicais possuem um alto número de espécies de peixes Siluriformes, muitas das quais popularmente conhecidas como cascudos no Brasil. Dados citogenéticos sobre três espécies de cascudos, capturadas na bacia do rio Araguaia são descritos no presente trabalho. Pterygoplichthys joselimaianus possui 2n=52, com 28 cromossomos metacêntricos (M), 16 submetacêntricos (SM) e 8 subtelecêntricos/acrocêntricos (ST/A) em ambos os sexos. Hemiancistrus spinosissimus revelou 2n=52, com fórmula cariotípica 26M+22SM+4ST, nos dois sexos. H. spilomma também possui 2n=52, porém, nesta espécie foi observado um sistema de cromossomos sexuais do tipo ZZ/ZW (25M+21SM+6ST para fêmeas e 24M+22SM+6ST para machos). As células de H. spinosissimus e P. joselimaianus mostraram um par de cromossomos portadores de Ag-RONs. Em H. spilomma, três pares de cromossomos portadores de Ag-RONs foram observados. Os dados apresentados neste trabalho revelam características cromossômicas particulares, importantes para um bom reconhecimento de ambas as espécies de Hemiancistrus e mostram a importância da inserção dos dados citogenéticos nos estudos taxonômicos e filogenéticos.

We present karyotypic characteristics and report on the occurrence of ZZ/ZW sex chromosomes in Ancistrus ranunculus (rio Xingu) and Ancistrus sp. "Piagaçu" (rio Purus), of the Brazilian Amazon. Ancistrus ranunculus has a modal number of 2n=48 chromosomes, a fundamental number (FN) of 82 for both sexes, and the karyotypic formula was 20m+8sm+6st+14a for males and 19m+9sm+6st+14a for females. Ancistrus sp. "Piagaçu" presented 2n=52 chromosomes, FN= 78 for males and FN= 79 for females. The karyotypic formula was 16m+8sm+2st+26a for males and 16m+9sm+2st+25a for females. The high number of acrocentric chromosomes in karyotype of Ancistrus sp. "Piagaçu" differs from the majority of Ancistrini genera studied so far, and may have resulted from pericentric inversions and translocations. The lower number of chromosomes in A. ranunculus indicates that centric fusions also occurred in the evolution of Ancistrus karyotypes. We conclude that karyotypic characteristics and the presence of sex chromosomes can constitute important cytotaxonomic markers to identify cryptic species of Ancistrus. However, sex chromosomes apparently arose independently within the genus and thus do not constitute a reliable character to analyze phylogenetic relations among Ancistrus species. Nós apresentamos características cariotípicas e registramos a ocorrência de cromossomos sexuais ZZ/ZW em Ancistrus ranunculus (rio Xingu) e Ancistrus sp. "Piagaçu" (rio Purus), da Amazônia Brasileira. Ancistrus ranunculus teve um número modal de 2n=48 cromossomos, um número fundamental (NF) de 82 para ambos os sexos, e a fórmula cariotípica 20m+8sm+6st+14a para machos e 19m+9sm+6st+14a para fêmeas. Ancistrus sp. "Piagaçu" apresentou 2n=52 cromossomos, NF=78 para machos e NF= 79 para fêmeas. A fórmula cariotípica foi de 16m+8sm+2st+26a para machos e 16m+9sm+2st+25a para fêmeas. O alto número de cromossomos acrocêntricos no cariótipo de Ancistrus sp. "Piagaçu" difere da maioria dos gêneros de Ancistrini estudada até o momento, e pode ter resultado de inversões pericêntricas e translocações. O número mais baixo de cromossomos em A. ranunculus indica que fusões cêntricas também ocorreram na evolução dos cariótipos de Ancistrus. Nós concluímos que as características cariotípicas e a presença de cromossomos sexuais podem constituir marcadores citotaxonômicos importantes para identificar espécies crípticas de Ancistrus. Entretanto, cromossomos sexuais aparentemente surgiram de forma independente dentro do gênero e, deste modo, não constituem um caráter confiável para ser usado em análises de relações filogenéticas entre espécies de Ancistrus.