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Type: Article
Published: 2023-01-06
Page range: 365-377
Abstract views: 365
PDF downloaded: 42

A new rheophilic species of Knodus Eigenmann (Characiformes: Characidae: Stevardiinae) from the upper rio Juruena, rio Tapajós basin, Chapada dos Parecis, Mato Grosso, Brazil

1Instituto de Biociências, Departamento de Biologia e Zoologia, Universidade Federal de Mato Grosso-UFMT, Avenida Fernando Corrêa, 2367, Boa Esperança, 78060-900, Cuiabá, MT, Brazil.
2Universidade Federal do Amazonas-UFAM, Departamento de Biologia, Programa de Pós-Graduação em Zoologia (PPGZOOL) 69080900, Manaus, AM, Brazil.
Pisces Knodus tiquiensis Diapomini Amazon Basin rheophily


Knodus ytuanama, new species, is described from the upper rio Juruena, rio Tapajós drainage, Amazon basin, Mato Grosso, Brazil. The new species differs from its congeners by presenting the interradial membranes of the caudal fin thickened, forming folds, and also differs from most congeners by the presence of a dark, wide midlateral stripe extending from the posterior margin of opercle to the middle caudal-fin rays, the absence of a humeral blotch in adults, and by having four rows of scales between the lateral line and the pelvic-fin origin, among another features. We also provide a discussion on the presence of membranous flaps on the fins as an adaptation for living in fast-water environments in Knodus ytuanama n. sp. as well as in a congener, K. tiquiensis.



  1. Aguiar, R.G., Guimarães, E.C., Brito, P.S., Santos, J.P., Katz, A.M., Dias, L.J.B.S., Carvalho-Costa, L.F. & Ottoni, F.P. (2022) A new species of Knodus (Characiformes: Characidae), with deep genetic divergence, from the Mearim and Munim river basins, Northeastern Brazil, and evidence for hidden diversity in adjacent river basins. Neotropical Ichthyology, 20(2), e210173.
    Camargo, M., Giarizzo, T. & Carvalho Jr., J. (2005) Levantamento ecológico rápido da fauna ictica de tributários do Médio-baixo Tapajós e Curu. Boletim do Museu Paraense Emílio Goeldi, 1 (2), 213–231.
    Deprá, G.C., Ota, R.R., Vitorino Júnior, O.B. & Ferreira, K.M. (2021) Two new species of Knodus (Characidae: Stevardiinae) from the upper rio Tocantins basin, with evidence of ontogenetic meristic changes. Neotropical Ichthyology, 19 (1), e200106.
    Dutra, G.M., Peixoto, L.A.W., Ochoa, L.E., Ohara, W.M., de Santana, C.D., Menezes, N.A. & Datovo, A. (2021) A new species of Amazonian bluntnose knifefish Brachyhypopomus (Gymnotiformes: Hypopomidae), with comments on its phylogenetic position. Systematics and Biodiversity, 19 (2), 1–26.
    Eigenmann, C.H. (1918) The American Characidae [Part 2]. Memoirs of the Museum of Comparative Zoology, 43, 103–208, pls. 9–11 + 13 + 17–29 + 33 + 78–80 + 93.
    Esguícero, A.L.H. & Castro, R.M.C. (2014) Knodus figueiredoi, a new characid from the rio das Garças, upper rio Araguaia basin, Brazil, with comments on the taxonomic limits of the genera Knodus and Bryconamericus (Teleostei: Characidae). Ichthyological Exploration of Freshwaters, 25 (1), 39–48.
    Ferreira, K.M. (2007) Análise filogenética e revisão taxonômica do gênero Knodus Eigenmann, 1911 (Characiformes: Characidae). Unpublished PhD Thesis, Universidade de São Paulo, Ribeirão Preto. [unknown pagination]
    Ferreira, K.M. & Carvajal, F.M. (2007) Knodus shinahota (Characiformes: Characidae) a new species from the río Shinahota, río Chapare basin (Mamoré system), Bolivia. Neotropical Ichthyology, 5 (1), 31– 36.
    Ferreira, K.M. & Lima, F.C.T. (2006) A new species of Knodus (Characiformes: Characidae) from the rio Tiquié, Upper rio Negro system, Brazil. Copeia, 2006 (4), 630–639.[630:ANSOKC]2.0.CO;2
    Ferreira, K.M., Mirande, J.M., Quagio-Grassiotto, I., Santana, J.C.O., Baicere-Silva, C.M. & Menezes, N.A. (2021) Testing the phylogenetic hypotheses of Stevardiinae Gill, 1858 in light of new phenotypic data (Teleostei: Characidae). Journal of Zoological Systematics and Evolutionary Research, 59, 1–26.
    Ferreira, K.M. & Netto-Ferreira, A.L. (2010) Knodus dorsomaculatus (Characiformes: Characidae), a new species from Teles Pires River, Tapajós River basin, Brazil. Journal of Fish Biology, 7 (3), 7468–7478.
    Fink, W.L. & Weitzman, S.H. (1974) The so-called cheirodontin fishes of Central America with descriptions of two new species (Pisces: Characidae). Smithsonian Contributions to Zoology, 172, 1–46.
    Fricke, R., Eschmeyer, W.N. & Van der Laan, R. (2022) Eschmeyer’s Catalog of fishes: genera, species, references. California Academy of Sciences, San Francisco, California. Available from: (accessed 13 December 2022)
    García-Melo, J.E., Oliveira, C., Silva, G.J C., Ochoa-Orrego L.E., Pereira, L.H.G. & Maldonado-Ocampo, J.A. (2019) Species delimitation of neotropical characins (Stevardiinae): Implications for taxonomy of complex groups. PLoS ONE, 14 (6), e0216786.
    Géry, J. (1977) Characoids of the world. TFH Publications, Neptune City, New Jersey, 672 pp.
    Lima, F.C.T., Britski, H.A. & Machado, F.A. (2004) New Knodus (Ostariophysi: Characiformes: Characidae) from the upper rio Paraguay basin, Brazil. Copeia, 2004 (3), 577–582.
    Malabarba, L.R. & Weitzman, S.H. (2003) Description of a new genus with six new species from southern Brazil, Uruguay and Argentina, with a discussion of a putative characid clade (Teleostei: Characiformes: Characidae). Comunicações do Museu de Ciências e Tecnologia da PUCRS, Série Zoologia, 16, 67–151.
    Menezes, N.A., Ferreira, K.M. & Netto-Ferreira, A.L. (2020) A new species of Knodus (Characiformes: Characidae: Stevardiinae) from the rio Aripuanã, rio Madeira basin, Brazil. Neotropical Ichthyology, 18 (2), e190139.
    Menezes, N.A. & Marinho, M.M.F. (2019) A new species of Knodus Eigenmann (Characiformes: Characidae: Stevardiinae) with comments on nuptial tubercles and gill gland in characiform fishes. PLoS ONE, 14 (7), e0217915.
    Menezes, N.A. & Weitzman, S.H. (1990) Two new species of Mimagoniates (Teleostei: Characidae: Glandulocaudinae), their phylogeny and biogeography and a key to the glandulocaudin fishes of Brazil and Paraguay. Proceedings of the Biological Society of Washington, 103 (2), 380–426.
    Mirande, J.M. (2010) Phylogeny of the family Characidae (Teleostei: Characiformes): from characters to taxonomy. Neotropical Ichthyology, 8 (3), 385–568.
    Mirande J.M. (2019) Morphology, molecules and the phylogeny of Characidae (Teleostei, Characiformes). Cladistics, 35 (3), 282–300. cla.12345
    Ohara, W.M. & Lima, F.C.T. (2015) Hyphessobrycon lucenorum (Characiformes: Characidae), a new species from the rio Madeira basin, Rondônia State, Brazil. Zootaxa, 3972 (4), 562–572.
    Ohara, W.M & Loeb, M.V. (2016) Ichthyofauna of the upper Juruena river on Chapada dos Parecis, Mato Grosso, Brazil. Biota Neotropica, 16 (4), 1–10.
    Ohara, W.M., Lima, F.C.T., Salvador, G.N. & Andrade, M.C. (2017) Peixes do rio Teles Pires: diversidade e guia de identificação. Gráfica e editora Amazonas, Aparecida de Goiânia, Goiânia, 399 pp.
    Peixoto, L.A.W. & Ohara, W.M. (2019) A new species of Eigenmannia Jordan & Evermann (Gymnotiformes: Sternopygidae) from rio Tapajós, Brazil, with discussion on its species group and the myology within Eigenmanniinae. PLoS ONE, 14 (8), e0220287, 1–30.
    Román-Valencia, C. (2000) Tres nuevas especies de Bryconamericus (Ostariophysi: Characidae) de Colombia y diagìostico del género. Revista de Biologia Tropical, 48, 449–464.
    Román-Valencia, C. (2003) Sistemática de las especies colombianas de Bryconamericus (Characiformes, Characidae). Dahlia, Revista de la Asociación Colombiana de Ictiólogos, 6, 17–58.
    Sabaj, M.H. (2020) Codes for natural history collections in ichthyology and herpetology. Copeia, 108 (3), 593–669.
    Schultz, L.P. (1944) The fishes of the family Characinidae from Venezuela, with description of seventeen new forms. Proceedings of the United States National Museum, 95, 235–367.
    Silva-Oliveira, C., Canto, A.L.C. & Ribeiro, F.R.V. (2016) Stream ichthyofauna of the Tapajós national Forest, Pará, Brazil. ZooKeys, 580, 125–144.
    Sousa, D.J.A., Silva-Oliveira, C., Canto, A.L.C. & Ribeiro, F.R.V. (2020) A new species of Knodus (Characiformes: Characidae) from the rio Cupari drainage, lower rio Tapajós basin, Brazil. Zootaxa, 4747 (3), 575–584.
    Taphorn, D.C. (1992) The characiform fishes of the Apure river drainage, Venezuela. Biollania, Edición Especial, 4, 1–537.
    Taylor, W.R. & Van Dyke, G.C. (1985) Revised procedures for clearing and staining small fishes and other vertebrates for bone and cartilage study. Cybium, 9 (2), 107–119.
    Thomaz, A.A.T., Arcila-Mesa, D.K., Ortí G. & Malabarba L.R. (2015) Molecular phylogeny of the subfamily Stevardiinae Gill, 1858 (Characiformes: Characidae): classification and the evolution of reproductive traits. BMC Evolutionary Biology, 15, 146. [PMID: 26195030]
    Vari, R.P. & Harold, A.S. (2001) Phylogenetic study of the Neotropical fish genera Creagrutus Gunther and Piabina Reinhardt (Teleostei: Ostariophysi: Characiformes), with a revision of the Cis-Andean Species. Smithsonian Contributions to Zoology, 613, 1–239.
    Weitzman, S.H. (1962) The osteology of Brycon meeki, a generalized characid fish, with an osteological definition of the family. Stanford Ichthyological Bulletin, 8 (1), 1–77.
    Zanata, A.M. & Ohara, W.M. (2020) A new species of Characidium (Characiformes: Crenuchidae) from the rio Madeira basin, Brazil. Journal of Fish Biology, 97 (6), 1681–1689.
    Zarske, A. (2008) Knodus borki sp. n.—ein neuer Salmler aus Peru mit einer ergänzenden Beschreibung von Boehlkea fredcochui Géry, 1966 (Teleostei: Characiformes: Characidae). Vertebrate Zoology, 58 (2), 159–171.