Distributions and phylogeographic data of rheophilic freshwater fishes provide evidences on the geographic extension of a central-brazilian amazonian palaeoplateau in the area of the present day Pantanal Wetland

Abstract

The analysis of the distribution patterns presented by examples of freshwater fishes restricted to headwater habitat: the anostomid Leporinus octomaculatus, the characins Jubiaba acanthogaster, Oligosarcus perdido, Moenkhausia cosmops, Knodus chapadae, Planaltina sp., the loricariid Hypostomus cochliodon, and the auchenipterid Centromochlus sp. provided evidences of a relatively recent shared history between the highlands of the upper rio Paraguay and adjoining upland drainage basins. Restricted to headwater of the uplands in the upper rio Paraguay and adjoining basins, these species provide biological evidence of the former extension of the central Brazilian plateau before the origin of the Pantanal Wetland. Disjunction took place due to an ecological barrier to these rheophilic taxa represented tectonic subsidence related to the origin of the Pantanal Wetland. Molecular analysis of Jubiaba acanthogaster revealed that the sample from the upper rio Xingu basin are the sister-group of a clade that includes samples from the upper rio Arinos (upper rio Tapajós) plus the upper rio Paraguay basin, supporting the assumption that the origin of the upper rio Paraguay basin causing vicariance between this basin and the upper rio Tapajós is the least vicariant event in the evolutionary history of the group.A análise do padrão de distribuição apresentado por exemplos de peixes de água doce neotropicais restritos à habitats reofílicos de cabeceira: o anostomídeo Leporinus octomaculatus, os caracídeos Jubiaba acanthogaster, Oligosarcus perdido, Moenkhausia cosmops, Knodus chapadae, Planaltina sp., o loricariídeo Hypostomus cochliodon e o auquenipterídeo Centromochlus sp. fornecem evidências de uma história compartilhada relativamente recente entre as terras altas do alto rio Paraguai e bacias de terras altas vizinhas. Restritas às cabeceiras das áreas altas nas bacias do alto rio Paraguai e bacias vizinhas, estas espécies fornecem evidências biológicas da pretérita extensão do Planalto Central Brasileiro anteriormente a origem tectônica da planície alagável do Pantanal. Disjunções ocorreram devido a barreira ecológica para estes taxons reofílicos representada pela subsidência tectônica associada à origem do Pantanal. A análise molecular de Jupiaba acanthogaster revelou que amostras da bacia do alto rio Xingu consistem no grupo-irmão de um clado mais inclusivo que inclui amostras do alto rio Arinos (alto rio Tapajós) mais o alto rio Paraguai, suportando a suposição de que a origem do alto rio Paraguai causou vicariância entre esta bacia e o alto rio Tapajós no último evento vicariante na história evolutiva do grupo.

Biogeography of Amazonian fishes: deconstructing river basins as biogeographic units

“…Biotic dispersal has been a major factor in historical hybridization and diversity generation in Amazonian rivers. This is a consequence of the importance of neotectonic activity and resulting rearrangements in the drainage network as diversity-generating factors, both in freshwater fishes in general (Burridge et al, 2006Cardoso, Montoya-Burgos, 2009;Waters et al, 2007) and neotropical fishes in particular Lima, Ribeiro, 2011;Ribeiro et al, 2013;Roxo et al, 2014;Tagliacollo et al, 2015). Those observations and ensuing conclusions prompt a reevaluation of the assumption that vicariant and dispersalist events in their pure form are the best explanation for the diversification of the neotropical fish fauna.…”

“…Amazonian river drainages have evolved by numerous events of reticulation (cf. Hubert, Renno, 2006;Lima, Ribeiro, 2011;Ribeiro et al, 2013;Dagosta et al, 2014). Géry (1962) was perhaps the first ichthyologist to recognize the great dynamism of South American drainages and the evanescence of their limits as biogeographic barriers to fish: "The Characoids (at least) have shown that they can pass readily from one basin to another in a very short time, geologically speaking" (Géry, 1962: page 67).…”

“…In all such examples, the hypothesis that ancestral populations of trans-basin taxa were once widespread in the two basins concerned can be refuted because the current watershed divide between them dates from the Precambrian and vastly predate the radiations of Teleostei in the Upper Cretaceous (c. 100-66 Ma) and predate also the origin of the basins themselves . Although the Brazilian Shield is ancient, its faults and sutures were tectonically active during the Cenozoic, due to the growth of the Atlantic Ocean in the divergent margin and the subduction of the Nazca Plate (Riccomini, Assumpção, 1999;Ribeiro et al, 2013). Such reactivations were responsible for the great fluvial dynamism of the Brazilian Shield (Lima, Ribeiro, 2011) and offered opportunities for faunistic mixtures between neighboring basins, promoting biotic dispersal.…”

“…This means that all such basins are historically (and compositionally) hybrid. It seems certain that the ichthyofaunal composition of Amazonian basins are mosaics of divergent elements of different origins, recruited in the course of separate and differently-aged events (Hubert, Renno, 2006;Lima, Ribeiro, 2011;Ribeiro et al, 2013;Dagosta et al, 2014).…”

Description of two extraordinary new species of freshwater stingrays of the genus Potamotrygon endemic to the rio Tapajós basin, Brazil (Chondrichthyes: Potamotrygonidae), with notes on other Tapajós stingrays

“…The black stingrays, occurring in Amazonian affluents draining the Brazilian Shield (P. rex in mid and upper rio Tocantins, P. henlei in rios Araguaia and lower Tocantins, and P. leopoldi in rio Xingu), form a species-group based on features discussed in Carvalho (2016), such as broadly rounded pelvic-fin apices and aspects of dorsal and ventral color, as well as having similar general proportions. An evolutionary affinity of P. albimaculata with other black stingrays reinforces a closer biogeographical relationship between the upper Tapajós basin and other north-flowing rivers draining the crystalline Brazilian Shield (see also Hubert & Renno, 2006;Lima & Ribeiro, 2011;Buckup et al, 2011), and not a closer relationship to rio Paraguai as demonstrated by other fishes (even though an affinity to rivers of the Brazilian Shield is maintained; Lima et al, 2007;Carvalho & Albert, 2011;Ribeiro et al, 2013). Potamotrygon albimaculata is distinct from P. henlei, P. leopoldi, and P. rex in having a strong blackish-brown color with yellowish to creamy white, rounded spots or faint ocelli smaller than eye diameter on disc, pelvic fins and tail.…”