Abstract

Relationships among species of Rivulus endemic to the Brazilian Amazonas river basin are evaluated through an analysis of morphological characters, including terminal taxa representative of all Rivulus lineages. Based on the present morphological phylogeny and previous molecular analyses, seven subgenera are recognized: Rivulus, Cynodonichthys, Anablepsoides, Benirivulus n. subgen., Laimosemion, Owiyeye n. subgen., and Melanorivulus n. subgen. Benirivulus is diagnosed by a unique colour pattern and includes a single species, R. beniensis, from the rio Madeira drainage; Owiyeye is diagnosed by the absence of dermosphenotic, a derived pattern of frontal squamation, and a colour pattern of the mandibular region, and includes species from the Amazonas and Orinoco river basins; Melanorivulus is diagnosed by an apomorphic morphology of preopercle, and derived colour patterns of male postorbital region and female unpaired fins, and includes species from southern Amazonian tributaries, Parana-Paraguay river system, and Parnaiba and Sao Francisco river basins. Eighteen species from the Amazonas river basin of Brazil are recognized as valid: R. urophthalmus, R. taeniatus, R. micropus, R. ornatus, R. beniensis, R. strigatus, and R. dibaphus, which are herein redescribed, and R. atratus, R. romeri, R. kirovskyi, R. uatuman, R. uakti, R. amanapira, R. tecminae, R. modestus, R. zygonectes, R. violaceus, and R. litteratus, described or redescribed recently. Field data indicate that species of different lineages included in the clade comprising Benirivulus, Laimosemion, Owiyeye, and Melanorivulus are found in different kinds of aquatic environments, suggesting a divergent evolution for habitat preference.

Resumo

As relacoes de parentesco entre especies de Rivulus endemicas da bacia amazonica brasileira sao avaliadas atraves de uma analise de caracteres morfologicos, incluindo taxons terminais representativos de todas as linhagens de Rivulus. Com base na presente filogenia morfologica e em analises moleculares anteriores, sete subgeneros sao reconhecidos: Rivulus, Cynodonichthys, Anablepsoides, Benirivulus n. subgen., Laimosemion, Owiyeye n. subgen., e Melanorivulus n. subgen. Benirivulus e diagnosticado por um padrao de colorido exclusivo e inclui uma unica especie, R. beniensis, da drenagem do rio Madeira; Owiyeye e diagnosticado pela ausencia de dermosfenotico, um padrao de escamacao frontal derivado e um padrao de colorido da regiao mandibular, e inclui especies das bacias dos rios Amazonas e Orinoco; Melanorivulus e diagnosticado pela morfologia apomorfica do pre-operculo e pelos padroes de colorido derivados de regiao pos-orbital de macho e de nadadeiras impares de femeas, e inclui especies dos tributarios amazonicos meridionais, do sistema de rios Parana-Paraguai, e bacias dos rios Paranaiba e Sao Francisco. Dezoito especies da bacia do rio Amazonas do Brasil sao reconhecidas como validas: R. urophthalmus, R. taeniatus, R. micropus, R. ornatus, R. beniensis, R. strigatus e R. dibaphus, que sao aqui redescritas, e R. atratus, R. romeri, R. kirovskyi, R. uatuman, R. uakti, sR. amanapira, R. tecminae, R. modestus, R. zygonectes, R. violaceus e R. litteratus, recentemente descritas ou redescritas. Dados de campo indicam que especies de distintas linhagens, incluidas no clado que compreende Benirivulus, Laimosemion, Owiyeye e Melanorivulus, sao encontradas em tipos deferentes de ambientes aquaticos, sugerindo uma evolucao divergente para preferencia de habitats.

Zusammenfassung

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