Skip to main content Skip to main navigation menu Skip to site footer
Responsive image
Issue: Vol. 4379 No. 1: 13 Feb. 2018
Type: Article
Published: 2018-02-13
DOI: 10.11646/zootaxa.4379.1.3
Page range: 47–73
Abstract views: 167
PDF downloaded: 3

Revision of Banded Knifefishes of the Gymnotus carapo and G. tigre clades (Gymnotidae Gymnotiformes) from the Southern Neotropics

University of Louisiana at Lafayette, Lafayette, LA, USA Corresponding author. PO Box 42452, 300 E St. Mary Blvd, Lafayette, LA, 70504
Universidade Federal do Rio Grande do Sul, RS, Brazil
Department of Biology, University of Central Florida, Orlando, FL, USA
University of Louisiana at Lafayette, Lafayette, LA, USA
Pisces Alpha taxonomy Biodiversity assessment Neotropical Species delimitation

Abstract

Banded Knifefishes (Gymnotus, Gymnotidae) comprise the most species-rich, ecologically tolerant (eurytopic), and geographically widespread genus of Neotropical electric fishes (Gymnotiformes), with 40 valid species occupying most habitats and regions throughout the humid Neotropics. Despite substantial alpha-taxonomic work in recent years, parts of the genus remain characterized by taxonomic confusion. Here we describe and delimit species of the G. carapo and G. tigre clades from the southern Neotropics, using body proportions (caliper-based morphometrics), fin-ray, scale and laterosensory-pore counts (meristics), quantitative shape differences (geometric morphometrics), osteology, color patterns and electric organ discharges. We report these data from 174 Gymnotus specimens collected from 100 localities throughout the southern Neotropics, and delimit species boundaries in a multivariate statistical framework. We find six species of the G. carapo clade (G. carapo australis, G. cuia n. sp., G. chimarrao, G. omarorum, G. pantanal, and G. sylvius), and two species of the G. tigre clade (G. inaequilabiatus and G. paraguensis) in the southern Neotropics. The new species G. cuia is readily distinguished from the morphologically similar and broadly sympatric G. c. australis by a shorter head and deeper head and body, and from the morphologically similar and sympatric G. omarorum by fewer lateral-line ventral rami and fewer pored lateral-line scales anterior to the first ventral ramus. We also review the geographic distributions of all eight species of the G. carapo and G. tigre clades in the southern Neotropics, showing that G. cuia is the most widespread species in the region. These results affirm the importance of understanding the structure of variation within and between species, both geographic and ontogenetic, in delimiting species boundaries.

 

References

  1. Albert, J.S. (2001) Species Diversity and Phylogenetic Systematics of American Knifefishes (Gymnotiformes, Teleosti). Miscellaneous Publications, Museum of Zoology, University of Michigan, 190, 1–140.

    Albert, J.S., de Campos Fernandes-Matioli, F.M. & de Almeida-Toledo, L.F. (1999) New Species of Gymnotus (Gymnotiformes, Teleostei) from Southeastern Brazil: Toward the Deconstruction of Gymnotus carapo. Copeia, 1999, 410.
    https://doi.org/10.2307/1447486

    Albert, J.S., Carvalho, T.P., Petry, P., Holder, M.A., Maxime, E.L., Espino, J., Corahua, I., Quispe, R., Rengifo, B., Ortega, H. & Reis, R.E. (2011) Aquatic biodiversity in the amazon: Habitat specialization and geographic isolation promote species richness. Animals, 1, 205–241.
    https://doi.org/10.3390/ani1020205

    Albert, J.S. & Crampton, W.G.R. (2001) Five new species of Gymnotus (Teleostei: Gymnotiformes) from an upper Amazon floodplain, with descriptions of electric organ discharges and ecology. Ichthyological Exploration of Freshwaters, 12, 241–266.

    Albert, J.S. & Crampton, W.G.R. (2003) Seven new species of the Neotropical electric fish Gymnotus (Teleostei, Gymnotiformes) with a redescription of G. carapo (Linnaeus). Zootaxa, 287 (1), 1–54.
    https://doi.org/10.11646/zootaxa.287.1.1

    Albert, J.S., Crampton, W.G.R., Thorsen, D.H. & Lovejoy, N.R. (2005) Phylogenetic systematics and historical biogeography of the Neotropical electric fish Gymnotus (Teleostei: Gymnotidae). Systematics and Biodiversity, 2, 375–417.
    https://doi.org/10.1017/S1477200004001574

    Albert, J.S. & Fink, W.L. (1996) Sternopygus xingu, a new species of electric fish from Brazil (Teleostei: Gymnotoidei), with comments on the phylogenetic position of Sternopygus. Copeia, 1996, 85–102.
    https://doi.org/10.2307/1446944

    Albert, J.S. & Miller, R.R. (1995) Gymnotus maculosus, a new species of electric fish (Chordata: Teleostei: Gymnotoidei) from Middle America, with a key to species of Gymnotus. Proceedings of the Biological Society of Washington, 108, 662–678.

    Bertaco, V.A., Ferrer, J., Carvalho, F.R. & Malabarba, L.R. (2016) Inventory of the freshwater fishes from a densely collected area in South America —a case study of the current knowledge of Neotropical fish diversity. Zootaxa, 4138 (3), 401–440.
    https://doi.org/10.11646/zootaxa.4138.3.1

    Cognato, D., Giora, J. & Fialho, C.B. (2007a) Análise da ocorrência de lesões corporais em três espécies de peixe elétrico (Pisces: Gymnotiformes) do sul do Brasil. Pan-American Journal of Aquatic Sciences, 2, 242–246.

    Cognato, D., Richer-de-Forges, M.M., Albert, J.S. & Crampton, W.G.R. (2007b) Gymnotus chimarrao, a new species of electric fish (Gymnotiformes: Gymnotidae) from Southern Brazil. Ichthyological Exploration of Freshwaters, 18, 375–382.

    Cognato, D.D.P. & Fialho, C.B. (2006) Reproductive biology of a population of Gymnotus aff. carapo (Teleostei: Gymnotidae) from southern Brazil. Neotropical Ichthyology, 4, 339–348.
    https://doi.org/10.1590/S1679-62252006000300005

    Craig, J.M., Crampton, W.G.R. & Albert, J.S. (2017) Revision of the polytypic electric fish Gymnotus carapo (Gymnotiformes, Teleostei), with descriptions of seven subspecies. Zootaxa, 4318 (3), 401–438.
    https://doi.org/10.11646/zootaxa.4318.3.1

    Crampton, W.G.R. & Albert, J.S. (2003) Redescription of Gymnotus coropinae (Gymnotiformes, Gymnotidae), an often misidentified species of Neotropical electric fish, with notes on natural history and electric signals. Zootaxa, 348 (1), 1–20.
    https://doi.org/10.11646/zootaxa.348.1.1

    Crampton, W.G.R. & Albert, J.S. (2004) Redescription of Gymnotus coatesi (Gymnotiformes, Gymnotidae): A Rare Species of Electric Fish from the Lowland Amazon Basin, with Descriptions of Osteology, Electric Signals, and Ecology. Copeia, 2004, 525–533.
    https://doi.org/10.1643/CI-03-246R1

    Crampton, W.G.R., Lovejoy, N.R. & Albert, J.S. (2003) Gymnotus ucamara: a new species of Neotropical electric fish from the Peruvian Amazon (Ostariophysi: Gymnotidae), with notes on ecology and electric organ. Zootaxa, 277 (1), 15–1.
    https://doi.org/10.11646/zootaxa.277.1.1

    Crampton, W.G.R., Rodríguez-Cattáneo, A., Lovejoy, N.R. & Caputi, A.A. (2013) Proximate and ultimate causes of signal diversity in the electric fish Gymnotus. The Journal of experimental biology, 216, 2523–41.
    https://doi.org/10.1242/jeb.083261

    Crampton, W.G.R., Thorsen, D.H. & Albert, J.S. (2005) Three New Species from a Diverse, Sympatric Assemblage of the Electric Fish Gymnotus (Gymnotiformes: Gymnotidae) in the Lowland Amazon Basin, with Notes on Ecology. Copeia, 2005, 82–99.
    https://doi.org/10.1643/CI-03-242R2

    Fernandes, F.M., Albert, J.S., Daniel-Silva, M.F.Z., Lopes, C.E., Crampton, W.G.R. & Almeida-Toledo, L.F. (2005) A new Gymnotus (Teleostei: Gymnotiformes: Gymnotidae) from the Pantanal Matogrossense of Brazil and adjacent drainages: continued documentation of a cryptic fauna. Zootaxa, 933 (1), 1–14.
    https://doi.org/10.11646/zootaxa.933.1.1

    Klingenberg, C.P. (2011) MorphoJ: an integrated software package for geometric morphometrics. Molecular Ecology Resources, 11, 353–357.
    https://doi.org/10.1111/j.1755-0998.2010.02924.x

    Lovejoy, N.R., Lester, K., Crampton, W.G.R., Marques, F.P.L. & Albert, J.S. (2010) Phylogeny, biogeography, and electric signal evolution of Neotropical knifefishes of the genus Gymnotus (Osteichthyes: Gymnotidae). Molecular phylogenetics and evolution, 54, 278–290.
    https://doi.org/10.1016/j.ympev.2009.09.017

    Malabarba, L.R., Neto, P.C., Bertaco, V.A., Carvalho, T.P., Santos, J.F. & Artioli, L.G.S. (2013) Via Sapiens Guia de identificação dos peixes da bacia do Rio Tramandaí. Via Sapiens, Porto Alegre, Brazil, 140 pp.

    Maldonado-Ocampo, J.A. & Albert, J.S. (2004) Gymnotus ardilai: a new species of Neotropical electric fish (Ostariophysi: Gymnotidae) from the Rio Magdalena Basin of Colombia. Zootaxa, 759, 1–10.

    Maxime, E.L. & Albert, J.S. (2009) A new species of Gymnotus (Gymnotiformes: Gymnotidae) from the Fitzcarrald Arch of southeastern Peru. Neotropical Ichthyology, 7, 579–585.
    https://doi.org/10.1590/S1679-62252009000400004

    Maxime, E.L. & Albert, J.S. (2014) Redescription of the Tuvirão, Gymnotus inaequilabiatus Valenciennes, 1839, Using High-Resolution X-ray Computed Tomography. Copeia, 14, 462–472.
    https://doi.org/10.1643/CI-13-054

    Maxime, E.L., Lima, F.C.T. & Albert, J.S. (2011) A New Species of Gymnotus (Gymnotiformes: Gymnotidae) from Rio Tiquié in Northern Brazil. Copeia, 1, 77–81.
    https://doi.org/10.1643/CI-10-009

    Richer-de-Forges, M.M., Crampton, W.G.R. & Albert, J.S. (2009) A New Species of Gymnotus (Gymnotiformes, Gymnotidae) from Uruguay: Description of a Model Species in Neurophysiological Research. Copeia, 2009, 538–544.
    https://doi.org/10.1643/CI-07-103

    Rohlf, F.J. (2015) The tps series of software. Hystrix, the Italian Journal of Mammalogy, 26, 1–4.

    Serra, S., Bessonart, J., de Mello, F.T., Duarte, A., Malabarba, L. & Loureiro, M. (2014) Peces del Río Negro. 1st Edition. Ministerio de Ganadería, Agricultura y Pesca, Montevideo, pp. 1-208.

    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.

    Valenciennes, A. (1847) Poissons. Catalogue des principales espèces de poissons, rapportées de l’Amérique méridionale. In: D’Orbigny, A. (Ed.), Voyage dans l’Amérique méridionale. Chez Pitois-Levrault, Paris, pp. 1–11.

    Waddell, J.C., Rodríguez-Cattáneo, A., Caputi, A.A. & Crampton, W.G.R. (2016) Electric organ discharges and near-field spatiotemporal patterns of the electromotive force in a sympatric assemblage of Neotropical electric knifefish. Journal of Physiology Paris, 110, 164–181.
    https://doi.org/10.1016/j.jphysparis.2016.10.004