A new species of Myloplus Gill (Characiformes, Serrasalmidae) from the Tumucumaque Mountain Range, Brazil and French Guiana, with comments on M. rubripinnis.

A new species of Myloplus Gill is described from Eastern Tumucumaque Mountain Range, drainages of the Oyapock and Araguari rivers between Brazil and French Guiana. The new species is diagnosed by having comparatively large scales on the flanks, resulting in lower counts when compared with congeners, i.e., 59 to 70 total perforated scales on lateral line, 31 to 35 longitudinal scales above lateral line, 24 to 29 longitudinal scales below lateral line, and 22 to 26 circumpeduncular scale rows. The new species most closely resembles Myloplus rubripinnis by sharing with this species a general rounded shape, a similar color pattern, and a high number of rays, i.e., 23 to 25 branched dorsal-fin rays and 35 to 38 branched anal-fin rays in the new species (vs. 24 to 25 and 32 to 40, respectively, in M. rubripinnis). After reviewing the available type-specimens of all Myloplus species, M. rubripinnis is re-diagnosed as having higher counts of branched dorsal-fin rays and anal-fin rays combined to tiny scales on flanks, i.e., 85 to 89 total perforated scales on lateral line, 38 to 45 longitudinal scales above lateral line, 33 to 42 longitudinal scales below lateral line, and 30 to 39 circumpeduncular scale rows.

A new species of Tometes Valenciennes 1850 (Characiformes: Serrasalmidae) from Tocantins-Araguaia River Basin based on integrative analysis of molecular and morphological data.

A new large serrasalmid species of Tometes is described from the Tocantins-Araguaia River Basin. Tometes siderocarajensis sp. nov. is currently found in the rapids of the Itacaiúnas River Basin, and formerly inhabited the lower Tocantins River. The new species can be distinguished from all congeners, except from T. ancylorhynchus, by the presence of lateral space between 1st and 2nd premaxillary teeth, and by the absence of lateral cusps in these two teeth. However, T. siderocarajensis sp. nov. can be differentiated from syntopic congener T. ancylorhynchus by an entirely black with mottled red body in live specimens, densely pigmented pelvic fins with a high concentration of dark chromatophores, and the presence of 39 to 41 rows of circumpeduncular scales (vs. silvery body coloration with slightly reddish overtones on middle flank during breeding period in live specimens, hyaline to slightly pale coloration on distalmost region of pelvic fins, and 30 to 36 rows of circumpeduncular scales). Additionally, molecular sequence shows that T. siderocarajensis sp. nov. is reciprocally monophyletic, and diagnosable from all congeners by having two autapomorphic molecular characters in the mitochondrial gene COI. The phylogenetic reconstruction still show that T. siderocarajensis sp. nov. is closely related to T. trilobatus. This is the first molecular study using an integrative taxonomic approach based on morphological and molecular sequence data for all described species of Tometes. These findings increase the number of formally described species of Tometes to seven. A key to the Tometes species is provided.

A new large species of Myloplus (Characiformes, Serrasalmidae) from the Rio Madeira basin, Brazil.

Myloplus zorroi sp. n. is described from the Rio Madeira Basin in Amazonia. The new species had been treated as an undescribed Tometes species because of the absence of a marked abdominal keel and few small spines forming its prepelvic serrae, features commonly found in the species of the Myleus clade of the Serrasalmidae (species of genera Myleus, Mylesinus, Ossubtus and Tometes) and also in species of Utiaritichthys. Myloplus zorroi sp. n. shares the following characters with its congeners and Utiaritichthys: molariform teeth (versus incisiform teeth in Myleus clade members); a labial row of premaxillary teeth separated from lingual row by an internal gap (versus absence of internal gap between premaxillary teeth rows); and an ascending process of premaxilla wide from its base to the tip (versus ascending process tapering from its base to the tip). Like other Myloplus species, Myloplus zorroi sp. n. differs from Utiariticthys by having a deeper body, approximately 60% of standard length (versus usually less than 50% of standard length). Considering all the morphological evidence, including the presence of 13-19 low spines forming the prepelvic serrae in Myloplus zorroi sp. n. versus more than 20 high spines forming a marked prepelvic keel in other species of Mylopus, the new species is here assigned to Myloplus. Comparisons of the new species with nominal species of Myloplus, representatives of the Myleus clade, and other related taxa are provided.

A new large Myloplus Gill 1896 from rio Negro basin, Brazilian Amazon (Characiformes: Serrasalmidae).

Myloplus lucienae, new species, is described from the blackwater tributaries of the rio Negro basin. It is one of the few Myloplus species typically found in rapid areas of the Guiana Shield. It is diagnosed from congeners by the combination of an elongated body, small prepelvic spines that reach anteriorly just to the middle of the abdomen between verticals through pectoral- and pelvic-fin origin, and large scales on flanks resulting in smaller scale counts.

Redescription and Geographical Distribution of the Endangered Fish Ossubtus xinguense Jégu 1992 (Characiformes, Serrasalmidae) with Comments on Conservation of the Rheophilic Fauna of the Xingu River.

The monotypic species Ossubtus xinguense was originally described based on scarce material putatively divided into juveniles and adults. Ossubtus xinguense has a restricted distribution and was previously known only from a few rapids downstream of the city of Altamira, in the Volta Grande stretch of the Middle Xingu River. Until recently, the species was rare in museums because its habitat (large rapids) is difficult to sample. Large-scale collecting efforts targeting rapids throughout the Xingu River basin have yielded an abundance of new material. Based on an analysis of the type series and freshly preserved specimens, we redescribe O. xinguense and provide detailed osteological descriptions along with comments about its relationships within Serrasalmidae. Furthermore, we expand the geographical distribution of the species and discuss its conservation status.

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.(AU)

Um novo Metynnis é descrito do rio Negro, no Brasil e Venezuela, e de tributários de água clara ou preta no Brasil, incluindo os rios Parauari, Uatumã, Trombetas e Sucunduri (o último pertencendo à bacia do rio Madeira). A nova espécie pode ser prontamente distinguida de todas as congêneres por possuir escamas da linha lateral com elevada concentração de cromatóforos escuros. Ela pode ser adicionalmente diferenciada por uma combinação de comprimento da cabeça 24,3-27,5% do CP, 13-18 rastros branquiais no ramo superior e 16-24 rastros branquiais no ramo inferior. A nova espécie é mais similar e provavelmente mais proximamente relacionada à Metynnis hypsauchen . Essas duas espécies compartilham padrão de colorido semelhante, forma do corpo e dimorfismo sexual na nadadeira anal. No entanto, elas diferem na presença de linha lateral com pigmentos mais claros em M. hypsauchen . A nova espécie também pode ser distinguida de M. hypsauchen por apresentar 56-65 escamas pré-dorsais e 90-104 escamas na linha lateral (vs . 36-54, e 65-82, respectivamente). Uma descrição osteológica detalhada da nova espécie é fornecida.(AU)

Tometes camunani (Characiformes: Serrasalmidae), a new species of phytophagous fish from the Guiana Shield, rio Trombetas basin, Brazil

A new species of Serrasalmidae, Tometes camunani, is described from the upper drainages of the rio Trombetas basin, Pará State, Brazil. The new species is distinguished from its congeners by having neurocranium with a slight concavity at the level of the frontal bone (vs. concavity absent, dorsal profile of neurocranium straight). It can be further distinguished from its congeners by having teeth with central cusp taller and acute (vs. central cusp shorter and with rounded edge in T. trilobatus), a terminal mouth (vs. upturned mouth in T. lebaili), and 12-26 prepelvic spines (vs. 0-9 in T. makue). The new species is strictly rheophilic like other species of Tometes, and occurs exclusively in the rapids of shield rivers, complex and fragile biotopes that are threatened by anthropogenic activities. An identification key to the species of the Myleus group is provided.

Uma espécie nova de Serrasalmidae, Tometes camunani, é descrita para as drenagens superiores da bacia do rio Trombetas, estado do Pará, Brasil. A espécie nova distingue-se dos congêneres pela presença de uma ligeira concavidade no neurocrânio na altura do frontal (vs. concavidade ausente, perfil dorsal do neurocrânio reto). Também pode ser adicionalmente distinguido dos seus congêneres por possuir dentes com a cúspide central mais alta e cume agudo (vs. cúspide central mais baixa e com cume arredondado em T. trilobatus), a boca terminal (vs. boca orientada para cima em T. lebaili), e 12-26 espinhos pré-pélvicos (vs. 0-9 em T. makue). A espécie nova é estritamente reofílica, como as demais espécies de Tometes, e ocorre exclusivamente nas zonas encachoeiradas dos rios de escudo, biótopos complexos, frágeis e ameaçados por ações antropogênicas. Uma chave de identificação para as espécies do grupo Myleus é apresentada.

Inventario taxonômico e redescriçâo das espécies de Anostomideos (Characiformes, Anostomidae) do Baixo Rio Tocantins, PA, Brasil

SUMMARYAs parts of the environmental studies conducted by INPA, from 1980 to 1986 in conjunction with ELETRONORTE in the area of influence of the Tucuruí Hydroeletric Instalation, twenty species of fish of the family Anostomidae from de lower Tocantins river, between Cametá and Itupiranga, state of Pará, are redescribed and ilustrated: Leporinus affins, L. tigrinus, L. desmotes,L. sp. 4, L. trifasciatus, L. friderici, L. sp. 1, L. sp. 2, L. sp. 3, L. granti, L. pachiycheilus, Laemolyta petiti, L. taeniata, Anostomoides laticeps, A. sp. 1, Anostomus ternetzi, Leporellus vittatus, Schizodon vittatus, Sartor tucuruiense and Abramites hypselenotus. Five of the species found (Laemolyta petiti, Leporinus affinis, L. sp. 2, Anostomoides sp. 1 and Sartor tucuruiense) have only been reporterd from the Tocantins-Araguai basins. On the other hand, several anostomid species, thar are widely distributed in the Amazon basin, were not encountered in the lower Tocantins basin. This fact may suggest that, from the rest of the Amazon basin and shows a high degree of endemimism. Most of the fish species are widely distributed in the lower Tocantins river but some showed a distinct preference for certain biotopes, for example Leporinus pachycheilus, L. desmotes, L. sp. 1 and Sartor tucuruiense for rapids; Leporinus sp. 3, Anostomus ternetzi for "igarapés", Schizodon vittatus and Laemolyta taeniata, for the analysis of meristic and morphometric characters, especially the number, form and distribution of the teeth, position of the mouth and number os scales.

RESUMOComo parte dos estudos ambientais que foram desenvolvidos pelo INPA, de 1980 a 1986, em convênio com a ELETRONORTE, na área de influência da UHE Tucuruí. são redescritas e ilustradas 20 espécies da damília Anostomidae do baixo rio Tocantins, entre Cametá e Itupiranga, PA: Leporinus affins, L. tigrinus, L. desmotes, L. sp. 4, L. trifasciatus, L. friderici, L. sp. 1, L. sp. 2, L. sp. 3, L. granti, L. pachiycheilus, Laemolyta petiti, L. taeniata, Anostomoides laticeps, A. sp. 1, Anostomus ternetzi, Leporellus vittatus, Schizodon vittatus, Sartor tucuruiense e Abramites hypselenotus. Cinco espécies (Laemolyta petiti, Leporinus affinis, L. sp. 2, Anostomoides sp. 1 e Sartor tucuruiense) somente foram assiladas até agora para a bacia do Tocantins-Araguaia. Por outro lado, outras espécies anostomídeos, melhor representadas na bacia Amazônica, não foram encontrados no baixo Tocantins, fazendo supor que esta área, do ponto de vista ictiológico, está relativamente iosolado do restante da bacia Amazônica e possui um certo grau de endemismo. A maioria das espécies ocorre amplamente no baixo Tocantins, sendo que algumas apresentam acentuada preferência por determinados biótopos, como por exemplo Leporinus pachycheilus, L. desmotes, L. sp. 1 e Sartor tucuruiense, por corredeiras; Leporinus sp. 3, Anostomus ternetzi, por igarapés; Schizodon vittatus e Laemolyta taeniata,por zonas marginais, periodicametne alagáveis. A partir da análise dos caracteres merísticas e morfométricas, sobretudo o número, a forma e disposição dos dentes, posição da boca e número de escamas, a apresentada uma chave de identificação para as espécies estudadas.

Inventário taxonômico dos anostomídeos (pisces, anostomidae) da bacia do rio uatumã-am, brasil, com descrição de duas espécies novas

This study concerns in taxonomic survey on the anostomid species of the Uatuma River. It includes redescriptions and illustrations of all species found at the area The utilized material cames from an intensive fish survey program carried out at the Uatumã River drainage, in the area affected by the Balbina and Pitinga hydroelectric dams, boths in the Amazonas state. It is deposited at the icththyological collection of the Instituto Nacional de Pesquisas da Amazonia (INPA). Twenty two anostomid species were found in the Uatumã River drainage, belonging to eight genera, of which Leporinuswere dominant, with twelve species, followed by Laemolyta, Anostomus, Anostomoidesand Pseudanos(with two species) and Schizodon, Anostomoides, Synaptolaemusand Gnathodolus,with one species. Two species, Leporinus uatumaensisn.sp. and Leporinus pitingain.sp. are considered new for science and here described. Diagnostic characters, distribution and habitat are cited; major ontogenetic changes in color patterns are also discussed. Several species had their distribution expanded.

O presente estudo trata do inventário, descrição e ilustração das espécies de anostomídeos da bacia do rio Uatumã. Ele foi desenvolvido com base na coleção de peixes do INPA, montada a partir de um intenso programa de coletas, na bacia do Uatumã, nas áreas de influência das usinas hidrelétricas de Balbina e Pitinga, ambas no estado do Amazonas. Para a maioria das espécies são feitos comentários sobre os caracteres diagnósticos, área de distribuição, biótopos preferenciais e principais variações do padrão de colorido entre adultos e jovens. As vinte e duas espécies identificadas pertencem a 8 gêneros, sendo Leporinusdominante, com 12 espécies, seguido de Laemolyta, Anostomuse Pseudanos,com duas e de Schizodon, Anostomoides, Synaptolaemuse Gnathodolus,com uma espécie cada. Dentre os peixes inventariados, duas espécies são consideradas novas e descritas (Leporinus uatumaensissp.n e Leporinus pitingaisp.n.) A partir deste estudo, as espécies tiveram sua área de ocorrência ampliada, já que algumas delas só haviam sido assinaladas para a localidade-tipo.

NOVAS OCORRÊNCIAS DE Leporinus pachycheilusBRITSKY, 1976 E DESCRIÇÃO DE UMA ESPÉCIE NOVA DO MESMO GRUPO NA AMAZÔNIA BRASILEIRA (OSTEICHTHYES, ANOSTOMIDAE)

The distribution area of Leporinus pachycheilusBritski, 1976 (Osteichthyes, Anostomidae), described from the Aripuanã river, is amplified to the Jamari and the Machado rivers, all tributaries of the Madeira river, and to the Uatumã, Araguari and Tocantins drainages. A complementary description of this species is given. Geographical variation on scales number was observed among diferent populations and a highly diverse color pattern at interpopulation and in-trapopulation levels. Leporinus juliin. sp., a new species close to L.pachycheilus,is decribed from Xingu and Trombetas drainage. This is a group of species restricted to the rapids of rivers draining Brazilian and Guianean shields and the uniques to present mouth completely inferior and incisiviform teeths, inserted side by side.

A área de distribuição de Leporinus pachycheilusBritski, 1976 (Teleostei, Anostomidae), descrita do rio Aripuanã, é ampliada para os rios Jamari e Machado, ambos afluentes do Madeira, assim como para os rios Uatumã, Araguari e Tocantins. Esta espécie apresenta alta variabilídade intra e inter-populacional no padrão de colorido, mas a consistência dos caracteres morfológicos indica que se trata de um grupo bem definido e não distinto do material descrito para a localidade tipo (rio Aripuanã). Uma nova espécie (Leporinus juliisp.n.) é descrita para os rios Xingu e Trombetas. Esta é muito semelhante a L. pachycheilus,mas difere basicamente pelo maior número de escamas ao redor do pedúnculo caudal (16 contra 12) e pelo padrão de colorido, formado por manchas arredondadas, ao invés de listras longitudinais. Ambas as espécies são restritas a trechos de corredeiras de rios que drenam os escudos das Guianas e do Brasil Central e são as únicas espécies de anostomídeos da Amazônia que apresentam boca totalmente inferior e dentes incisiviformes, dispostos lado a lado.