Ecomorphological differences between Rhamdia (Bleeker, 1858) populations from the Iguaçu River basin

Abstract

Morphological and genetic evidences suggest that Rhamdia branneri and Rhamdia voulezi, currently considered synonymous of Rhamdia quelen, are in fact two valid species. Furthermore, in the taxonomic revision of R. quelen, no exemplars from the Iguaçu River were examined, which makes the synonymy doubtful. Considering the two species as valid, it was hypothesized that R. branneri and R. voulezi have ecomorphological differences, with the objective to verify if they can be considered ecologically distinct. Ecomorphological characterization was conducted using ecomorphological indices. For statistical analysis, a Principal Component Analysis (PCA), a Multiresponse Permutation Procedure (MRPP), and a Discriminant Analysis (DA) were performed. The ordination provided by the PCA evidenced ecomorphological separation, with R. branneri having morphological aspects related to benthic fishes, and R. voulezi having morphological characteristics related to pelagic and lentic habitats. The DA results confirmed the morphological tendencies found in the PCA, and the MRPP showed significant statistical differences between the ecomorphology of Rhamdia species. In this way, the initial hypothesis can be corroborated. These results allied to information about diet, genetics, and reproduction can be helpful for the elucidation of the taxonomic status of R. branneri and R. voulezi. Resumo: Evidências morfológicas e genéticas sugerem que Rhamdia branneri e Rhamdia voulezi, atualmente consideradas sinônimas de Rhamdia quelen, são, de fato, duas espécies válidas. Adicionalmente, na revisão taxonômica de R. quelen nenhum exemplar do rio Iguaçu foi examinado, o que torna a sinonímia duvidosa. Considerando as duas espécies como válidas, foi testada a hipótese de que R. branneri e R. voulezi possuem diferenças ecomorfológicas, com o objetivo de verificar se elas podem ser consideradas ecologicamente distintas. A caracterização ecomorfológica foi conduzida utilizando os índices ecomorfológicos. Para a análise estatística foram feitas Análise de Componentes Principais (ACP), Procedimento de Permutação Multiresposta (PPMR) e Análise Discriminante (AD). A ordenação proveniente da ACP evidenciou separação ecomorfológica, com R. branneri possuindo aspectos morfológicos relacionados a peixes bentônicos e R. voulezi possuindo características morfológicas relacionadas a habitats pelágicos e lênticos. Os resultados da AD confirmaram as tendências morfológicas encontradas na ACP, e o PPMR mostrou diferenças estatísticas significativas entre as espécies de Rhamdia. Dessa maneira, a hipótese inicial pôde ser corroborada. Esses resultados, aliados a informações sobre a dieta, genética e reprodução, podem ser úteis para a elucidação do status taxonômico de R. branneri e R. voulezi. Palavras-chave: endemismo, Heptapteridae, Rhamdia voulezi, Rhamdia branneri, Rhamdia quelen, ecomorfologia.

DNA barcoding confirms the occurrence of Rhamdia branneri and Rhamdia voulezi (Siluriformes: Heptapteridae) in the Iguaçu River Basin

“…DNA barcoding analysis corroborates the morphological (Shibatta, Garavello, 1995;Garavello, Shibatta, 2016), karyotypic (Abucarma, Martins-Santos, 2001;Moraes et al, 2007;Garcia et al, 2003;Garcia et al, 2010;Martinez et al, 2011) and ecomorphological studies (Mise et al, 2013), confirming R. branneri and R. voulezi as valid species. The correct definition of MOTUs and definition of the species is essential to the conservation of wild stocks and to minimizing the possibility of species translocations through aquaculture activity.…”

“…Although there is overlap in the number of chromosomes, morphological studies support the evidence in considering R. voulezi and R. branneri as valid independent species (Garcia, 2009;Baumgartner et al, 2012;Mise et al, 2013). Recently, Garavello, Shibatta (2016) described a series of morphological characteristics that discriminate between R. voulezi and R. branneri, suggesting provision of the names for both.…”

“…The characteristics associated with chromosome B and karyotype variations between species of the genus Rhamdia from the Iguaçu River, for example, showed that R. voulezi and R. branneri are distinct from R. quelen (Abucarma, Martins-Santos, 2001;Garcia et al, 2010). Recently Mise et al (2013) and Garavello, Shibatta (2016) detected evident morphometric characteristics for the reappraisal of R. branneri and R. voulezi from the Iguaçu River Basin.…”

Reappraisal of Rhamdia branneri Haseman, 1911 and R. voulezi Haseman, 1911 (Siluriformes: Heptapteridae) from the rio Iguaçu with notes on their morphometry and karyotype

“…As second consideration, concerning to morphometry, Mise et al (2013) advanced a PCA on populations of R. branneri and R. voulezi that indicates an obvious segregation between these two species along the first axis of their figure 2. Those authors also revealed that most of the morphologic characters that separate the Rhamdia species from Iguaçu are related to body shape.…”

“…Recently, Mise et al (2013), also in a collection from the Iguaçu, revealed that morphological characters split the species R. branneri and R. voulezi.…”