Abstract
A new species of the genus Melanorivulus belonging to the Melanorivulus pictus species group is herein described, from a tributary of the Rio Grande, Rio Paraná basin, São Paulo State, Brazil. The new species can be distinguished from all other species of the Melanorivulus pictus species group by the unique presence of sides of body of males light bluish gray with 10–12 oblique red bars, 8 of which chevron-like, bifurcated and complete, i.e., running from dorsum to ventral area, and 2–4 incomplete, with vertices of the chevron-like bars along midbody, pointing forward. Comments on the putative relationships of the new species, as well as concerning its conservation status, are presented.
References
Costa, W.J.E.M. (1989) Descrição de cinco novas espécies de Rivulus das bacias dos rios Paraná e São Francisco (Cyprinodontiformes, Rivulidae). Revista Brasileira de Zoologia, 6, 523–534.
Costa, W.J.E.M. (1995) Pearl killifishes: The Cynolebiatinae. Systematics and Biogeography of a Neotropical annual fish subfamily (Cyprinodontiformes: Rivulidae). TFH Publications, Neptune City, 128 pp.
Costa, W.J.E.M. (2005) Seven new species of the killifish genus Rivulus (Cyprinodontiformes, Rivulidae), from the Paraná, Paraguay and upper Araguaia river basins, central Brazil. Neotropical Ichthyology, 3, 69–82.
https://doi.org/10.1590/S1679-62252005000100003
Costa, W.J.E.M. (2006a) Relationships and taxonomy of the killifish genus Rivulus (Cyprinodontiformes: Aplocheiloidei: Rivulidae) from the brazilian Amazonas river basin, with notes on historical ecology. aqua, Journal of Ichthyology and Aquatic Biology, 11, 133–175.
Costa, W.J.E.M. (2006b) Rivulus kayapo n. sp. (Teleostei: Cyprinodontiformes: Rivulidae): a new killifish from the Serra dos Caiapós, upper rio Araguaia basin, Brazil. Zootaxa, 1368, 49–56.
Costa, W.J.E.M (2007) Rivulus illuminatus, a new killifish from the serra dos Caiapós, upper rio Paraná basin, Brazil (Teleostei: Cyprinodontiformes: Rivulidae). Ichthyological Exploration of Freshwaters, 18, 193–198.
Costa, W.J.E.M. (2008) Rivulus formosensis, a new aplocheiloid killifish from the upper Corrente River drainage, upper rio Paraná basin, central Brazil. (Cyprinodontiformes: Rivulidae). Ichthyological Exploration of Freshwaters, 19, 85–89.
Costa, W.J.E.M (2011) Phylogenetic position and taxonomic status of Anablepsoides, Atlantirivulus, Cynodonichthys, Laimosemion and Melanorivulus (Cyprinodontiformes: Rivulidae). Ichthyological Exploration of Freshwaters, 22, 233–249.
Costa, W.J.E.M. (2013) A new killifish of the genus Melanorivulus from the upper Paraná river basin, Brazil (Cyprinodontiformes: Rivulidae). Vertebrate Zoology, 63 (3), 277–281.
Costa, W.J.E.M. (2016) Comparative morphology, phylogenetic relationships, and taxonomic revision of South American killifishes of the Melanorivulus zygonectes species group (Cyprinodontiformes: Rivulidae). Ichthyological Exploration of Freshwaters, 27 (2), 107–152.
Costa, W.J.E.M. (2017) Three new species of the killifish genus Melanorivulus from the central Brazilian Cerrado savanna (Cyprinodontiformes, Aplocheilidae). ZooKeys, 645, 51–70.
https://doi.org/10.3897/zookeys.645.10920
Costa, W.J.E.M. (2018) Three new species of the killifish genus Melanorivulus from the Rio Paraná Basin, central Brazilian Cerrado (Cyprinodontiformes, Aplocheilidae). Zoosystematics and Evolution, 94 (1), 17–27.
https://doi.org/10.3897/zse.94.21321
Costa, W.J.E.M., Bragança, P.H.N. & Ottoni, F.P. (2015) A new miniature killifish of the genus Melanorivulus (Cyprinodontiformes: Rivulidae) from the coastal plains of north-eastern Brazil. Vertebrate Zoology, 65, 31–35.
Hoedeman, J.J. (1958) The frontal scalation pattern in some groups of toothcarps (Pisces, Cyprinodontiformes). Bulletin of Aquatic Biology, 1, 23–28.
Nielsen, D.T.B., Aguiar, P.A.B., Ywamoto, E.V. & Passos, M.A. (2016).Melanorivulus polychromus, a new species of killifish from the rio São José dos Dourados drainage, middle rio Paraná basin, southwestern Brazil, with a redescription of Melanorivulus apiamici (Cyprinodontiformes: Rivulidae). aqua, International Journal of Ichthyology, 22 (2), 79–88.
Nóbrega, M.T., Collischonn, W., Tucci, C.E.M. & Paz, A.R. (2011) Uncertainty in climate change impacts on water resources in the Rio Grande Basin, Brazil. Hydrology and Earth System Sciences, 15 (2), 585–595.
https://doi.org/10.5194/hess-15-585-2011
Sabaj, M.H. (Ed.) (2019) Standard symbolic codes for institutional resource collections in herpetology and ichthyology: an online reference. Version 7.1. 21 March 2019. American Society of Ichthyologists and Herpetologists, Washington, D.C. Electronically accessible. Available from: http://www.asih.org/ (accessed 19 August 2020)
Taylor, W.R. & Van Dyke, G.C. (1985) Revised procedures for staining and clearing small fishes and other vertebrates for bone and cartilage study. Cybium, 9, 107–119.
Volcan, M.V., Klotzel, B.& Lanés, L.E.K. (2017) Two new species of Melanorivulus (Cyprinodontiformes: Cynolebiidae) from Rio Verde drainage, upper Rio Paraná basin, Brazil. Zootaxa, 4236 (1), 82–94.
https://doi.org/10.11646/zootaxa.4236.1.4
Volcan, M.V., Severo-Neto, F. & Lanés,. L.E.K. (2018) Unrecognized biodiversity in a world’s hotspot: three new species of Melanorivulus (Cyprinodontiformes: Rivulidae) from tributaries of the right bank of the Rio Paraná basin, Brazilian Cerrado. Zoosystematics and Evolution, 94 (2), 263–280.
https://doi.org/10.3897/zse.94.24406