Wilson J. E. M. Costa, 2006, Rivulus kayapo n. sp. (Teleostei: Cyprinodontiformes: Rivulidae): a new killifish from the serra dos Caiapós, upper rio Araguaia basin, Brazil., Zootaxa 1368, pp. 49-56: 50

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[[ Genus Rivulus   ZBK   ]]

The killifish genus Rivulus Poey   ZBK   constitutes the most speciose and geographically widespread assemblage of aplocheiloid fishes. A great diversity in species of Rivulus   ZBK   has long been known from Central America and the northern part of South America, including river basins draining the Guyana Shield and the western portion of the Rio Amazonas basin (Costa, 2003, 2006). However, a rich diversity of species has only recently been reported for the central part of South America, including southern tributaries of the rio Amazonas (Tocantins, Araguaia, Xingu, and Tapajós) and the rio Paraná-Paraguay- basin (Costa, 1995a, 2005). Rivulus   ZBK   is still a poorly diagnosed genus, but it contains well-corroborated monophyletic units. This is the case for an assemblage formerly known as the Rivulus punctatus species group   ZBK   (Costa, 1995a), now considered to comprise the subgenus Melanorivulus   (Costa, 2006), a well supported clade endemic to central South America. This subgenus comprises 18 species: Rivulus apiamici Costa   ZBK   , R. cyanopterus Costa   ZBK   , R. dapazi Costa   ZBK   , R. decoratus Costa   ZBK   , R. egens Costa   ZBK   , R. litteratus Costa   ZBK   , R. modestus Costa   ZBK   , R. paracatuensis Costa   ZBK   , R. parnaibensis Costa   ZBK   , R. pictus Costa   ZBK   , R. pinima Costa   ZBK   , R. punctatus Boulenger   ZBK   , R. rossoi Costa   ZBK   , R. rutilicaudus Costa   ZBK   , R. scalaris Costa   ZBK   , R. violaceus Costa   ZBK   , R. vittatus Costa   ZBK   , and R. zygonectes Myers   ZBK   . A new species of this clade, collected in the rio Caiapó drainage of the upper Rio Araguaia basin, is herein described.