Hypopygus Explained

Hypopygus is a genus of South American gymnotiform knifefishes native to the Amazon, Orinoco and upper Paraguay basins, as well as rivers in the Guianas.[1] [2] They are often common, and found near submerged roots, aquatic vegetation and leaf-litter in streams, edges of rivers and floodplains.[1] They are regularly found among vegetation in floating meadows, a habitat that often contains little oxygen, but they are well-adapted to this.[3]

They are well-camouflaged and brown in color with a banded/mottled pattern.[1] [2] [4] They generally resemble the related Steatogenys, but are smaller,[5] reaching up to NaNcm (-2,147,483,648inches) in total length depending on the exact species of Hypopygus. The smallest is H. hoedemani, which is the second-smallest knifefish,[1] after Microsternarchus brevis.[6] They are nocturnal and feed on small invertebrates. During the day they remain hidden, often in groups that may number several dozen individuals.[1]

Taxonomy and species

Hypopygus has traditionally been included in the family Hypopomidae, but a comprehensive molecular study from 2015 showed it belongs in Rhamphichthyidae,[7] and this has been followed by recent authorities.[8] [9]

There are currently eight recognized species of Hypopygus according to FishBase, but studies have shown that "Stegostenopos" cryptogenes (a species that reaches up to 15abbr=onNaNabbr=on long) belongs in Hypopygus and this is followed by the Catalog of Fishes.[1] [8] [10]

Notes and References

  1. de Santana, C.D. . W.G.R. Crampton . amp . 2011 . Phylogenetic interrelationships, taxonomy, and reductive evolution in the Neotropical electric fish genus Hypopygus (Teleostei, Ostariophysi, Gymnotiformes) . Zoological Journal of the Linnean Society . 163 . 4 . 1096–1156 . 10.1111/j.1096-3642.2011.00736.x. free .
  2. Peixoto . Luiz Antônio Wanderley . Dutra . Guilherme Moreira . de Santana . Carlos David . Wosiacki . Wolmar Benjamin . amp . A new species of the electric fish genus Hypopygus (Gymnotiformes: Hypopomidae) from the Lower Amazon Basin, Brazil . Copeia . 2013 . 2013 . 2 . 232–237 . 10.1643/CI-12-087. 84089305 .
  3. Carvalho, L.N. . L. Fidelis . R. Arruda . A. Galuch . K. Zuanon . amp . 2013 . Second floor, please: the fish fauna of floating litter banks in Amazonian streams and rivers . Neotropical Ichthyology . 11 . 1 . 78–91 . 10.1590/S1679-62252013000100010 . free .
  4. Nijssen, H. . I.J.H. Isbrücker . amp . 1972 . On Hypopygus lepturus, a little known dwarf gymnotid fish from South America (Pisces, Cypriniformes, Gymnotoidei) . Zoologische Mededelingen . 14763 . 160–176 .
  5. Crampton, W.G.R. . D.C. Thorsen . J.S. Albert . N.R. Lovejoy . amp . 2004 . Steatogenys ocellatus: a new species of neotropical electric fish (Gymnotiformes: Hypopomidae) from the Lowland Amazon Basin . Copeia . 2004 . 1 . 78–91 . 10.1643/ci-03-072ri. 85693926 .
  6. Cox Fernandes, C. . Nogueira, A. . Williston, A. . Alves-Gomes, J.A. . amp . 2015 . A new species of electric knifefish from the Rio Negro, Amazon basin (Gymnotiformes: Hypopomidae, Microsternarchini) . Proceedings of the Academy of Natural Sciences of Philadelphia . 164 . 1 . 213–227 . 10.1635/053.164.0113. 86768117 .
  7. Tagliacollo, V.A. . Bernt, M.J. . Craig, J.M. . Oliviera, C. . Albert, J.S. . amp . 2015 . Model-based Total Evidence phylogeny of Neotropical electric knifefishes (Teleostei, Gymnotiformes) . Molecular Phylogenetics and Evolution . 95 . 20–33 . 10.1016/j.ympev.2015.11.007 . 26616344 . free . 11449/168204 . free .
  8. Ferraris Jr, C.J. . C.D. de Santana . R.P. Vari . amp . 2017 . Checklist of Gymnotiformes (Osteichthyes: Ostariophysi) and catalogue of primary types . Neotropical Ichthyology . 15 . 1 . e160067 . 10.1590/1982-0224-20160067 . free .
  9. Book: van der Sleen, P. . J.S. Albert . amp . 2017 . Field Guide to the Fishes of the Amazon, Orinoco, and Guianas . Princeton University Press . 337–341 . 978-0691170749 .
  10. Web site: Eschmeyer, W.N. . R. Fricke . R. van der Laan . amp . 8 May 2018 . Catalog of Fishes . California Academy of Sciences . 8 May 2018 .

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