The Guiana Shield

Lujan, Nathan K.; Armbruster, Jonathan W.

doi:10.1525/california/9780520268685.003.0013

Cited by 57 publications

(83 citation statements)

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“…L17, as well as others ancestral species of the Pseudancistrus barbatus group and even species of Ancistrini (Lujan and Armbruster 2011). The movement of fish species around adjacent drainages could be explained by two hydrographic reconfiguration process: headwater capture events (geomorphological phenomenon) and marine regressions (sea level oscillation).…”

Section: Discussionmentioning

confidence: 99%

New species of the Pseudancistrus barbatus group (Siluriformes, Loricariidae) with comments on its biogeography and dispersal routes

Silva¹,

Roxo²,

Britzke³

et al. 2014

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A new species of Pseudancistrus is described from the Tapajós Basin, and assigned to the P. barbatus group by having hypertrophied odontodes along the snout and lacking evertible cheek plates. The new species is distinguished from other species in that group (P. barbatus, P. corantijniensis, P. depressus and P. nigrescens) by its pattern of spots, length and color of snout odontodes, greater head depth, cleithral width, anal-fin spine length, peduncle depth and internares width. Molecular phylogenetic results corroborate placement of the new species in the Pseudancistrus barbatus group which is otherwise distributed in the Xingu Basin and rivers draining the Guyana Shield into the Atlantic Ocean. Topology tests strongly reject alternative hypotheses supporting close relationships with Guyanancistrus, Lithoxancistrus or the species Pseudancistrus pectegenitor, P. sidereus and P. genisetiger. Additionally, we propose two hypotheses on the distribution of the new species in the rio Tapajós, a Brazilian Shield drainage. The first one proposes that ancestral stock of the P. barbatus group was widely distributed throughout rivers draining the Guyana and Brazilian shields, and the species P. zawadzkii and Pseudancistrus sp. L17 are in the limit of the distribution for the group in Tapajós and Xingu rivers. The second hypothesis proposes that ancestral stock of the P. barbatus group was restricted to Guyana Shield rivers, and that headwater capture events permitted several dispersal routs through Guyana and Amazon rivers, permitted that the ancestral lineages of Pseudancistrus sp. L17 and P. zawadzkii reached the rivers of Amazon basin.

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Section: Discussionmentioning

confidence: 99%

New species of the Pseudancistrus barbatus group (Siluriformes, Loricariidae) with comments on its biogeography and dispersal routes

Silva¹,

Roxo²,

Britzke³

et al. 2014

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“…The upper Mazaruni is separated from the lowlands by a series of steep rapids and waterfalls (Alofs et al., ); the upper Potaro is separated from the lowlands by the 226 m drop of Kaieteur Falls (Hardman et al., ); and streams on Tafelberg tepui flow over the sheer edge of the tepui, eventually draining to the right arm of the Coppename River. Although the upper Potaro and upper Mazaruni samples are geographically adjacent, there is no direct connection between these rivers (Lujan & Armbruster, ).…”

Section: Methodsmentioning

confidence: 99%

Fish biogeography in the “Lost World” of the Guiana Shield: Phylogeography of the weakly electric knifefish Gymnotus carapo (Teleostei: Gymnotidae)

Lehmberg

Elbassiouny

Bloom

et al. 2018

Journal of Biogeography

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Aim The Guiana Shield region exhibits extraordinary topography that includes sheer, flat‐topped mountains (tepuis) atop an upland platform. Rivers of the eastern Pakaraima Mountains descend to Atlantic coastal lowlands, often traversing spectacular rapids and waterfalls. For fish species distributed in both uplands and lowlands, it is unclear whether these rapids and waterfalls present population or biogeographical boundaries. We sought to test this using the geographically widespread banded‐electric knifefish (Gymnotus carapo) as a model. Location The Guiana Shield region of South America. Methods We sampled 60 Gymnotus carapo specimens from the Guiana Shield region, and 75 G. carapo and closely related species from other parts of South America. We sequenced the mitochondrial cytochrome b gene and an intron from the nuclear S7 ribosomal protein gene, and used maximum likelihood and Bayesian tree‐building approaches to generate phylogenetic trees of haplotypes. Results Haplotype sharing is minimal between populations separated by elevational barriers. We found evidence for two main haplotype clades in the Guiana Shield: one distributed in Atlantic coastal regions that includes most lowland samples, and one inland that includes most upland samples. Inland Guiana samples are more closely related to samples from the Amazon basin than to those of Atlantic coastal regions. A single sample from Tafelberg tepui in Suriname was most closely related to the Atlantic coastal lineages. Main conclusions Riverine barriers that result from steep elevational gradients in the Guiana Shield inhibit gene flow between uplands and lowlands, even for a widely distributed species. Biogeographical relationships of Guiana Shield G. carapo are complex, with most upland lineages showing affinities to the Amazon basin, rather than to nearby lowland drainages of the Atlantic coast.

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“…Of these species, only two, C. multilineatus and C. sanctigabrielis are known solely from within the rio Negro system with the latter species only known from its type locality above the rapids of São Gabriel da Cachoeira. Species from the upper portions of the río Orinoco and rio Negro which are conjoined via the río Casiquiare are presumably isolated from lower portions of their respective drainages by the Atures and Maipures rapids in the southern portions of the río Orinoco basin and the rapids at São Gabriel along the rio Negro in the northern Amazon (Lima & Ribeiro, 2011;Lujan & Armbruster, 2011). Albert et al (2006) similarly hypothesized that the rapids at São Gabriel might be physical barriers blocking the dispersal of gymnotiforms from the Orinoco to Amazon lowlands.…”

Section: Coloration In Alcoholmentioning

confidence: 99%

New species of Cyphocharax (Characiformes: Curimatidae) from the upper rio Negro, Amazon basin

2014

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A new species of Cyphocharax, Curimatidae, apparently endemic to the blackwater upper rio Negro of the Amazon basin in northern Brazil, is described. The new species is readily distinguished from its congeners by the presence of a distinctly longitudinally elongate, posteriorly vertically expanding patch of dark pigmentation along the midlateral surface of the caudal peduncle, with the patch extending from the base of the middle caudal-fin rays anteriorly past the vertical through the posterior terminus of the adipose fin. The new species additionally differs from all congeners in details of body and fin pigmentation and meristic and morphometric ratios. Evidence for the assignment of the species to Cyphocharax and the occurrence of other species of the Curimatidae apparently endemic to the upper rio Negro catchment is discussed.Uma espécie nova de Cyphocharax, Curimatidae, aparentemente endêmica das águas escuras do rio Negro, bacia amazônica no norte do Brasil, é descrita. A espécie nova é prontamente distinguida de suas congêneres pela presença de uma mancha escura distintamente alongada longitudinalmente e posteriormente expandida na vertical ao longo da superfície lateral do pedúnculo caudal, sendo estendida da base dos raios medianos da nadadeira caudal até a linha vertical do término da nadadeira adiposa. Adicionalmente, a espécie nova difere de todas as congêneres nos detalhes do corpo, pigmentação das nadadeiras e nas proporções merísticas e morfométricas. As evidências para alocação da espécie no gênero Cyphocharax e a ocorrência de outras espécies de Curimatidae aparentemente endêmicas do alto rio Negro são discutidas.

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The Guiana Shield

Cited by 57 publications

References 0 publications

New species of the Pseudancistrus barbatus group (Siluriformes, Loricariidae) with comments on its biogeography and dispersal routes

New species of the Pseudancistrus barbatus group (Siluriformes, Loricariidae) with comments on its biogeography and dispersal routes

Fish biogeography in the “Lost World” of the Guiana Shield: Phylogeography of the weakly electric knifefish Gymnotus carapo (Teleostei: Gymnotidae)

New species of Cyphocharax (Characiformes: Curimatidae) from the upper rio Negro, Amazon basin

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