''Hemiodus'' is a genus of

halftooth The Hemiodontidae are a small family of freshwater characins found in northern South America, south to the Paraná-Paraguay Basin. The larger species are popular food fish. Hemiodontids have a streamlined body shape; many are fast-swimming, and ...

s from

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

with the greatest

species richness Species richness is the number of different species represented in an ecological community, landscape or region. Species richness is simply a count of species, and it does not take into account the abundances of the species or their relative a ...

in the

Amazon Basin The Amazon basin is the part of South America drained by the Amazon River and its tributaries. The Amazon drainage basin covers an area of about , or about 35.5 percent of the South American continent. It is located in the countries of Bolivi ...

, but also found in the

Orinoco The Orinoco () is one of the longest rivers in South America at . Its drainage basin, sometimes known as the Orinoquia, covers , with 76.3 percent of it in Venezuela and the remainder in Colombia. It is the fourth largest river in the wor ...

Essequibo Essequibo is the largest traditional region of Guyana but not an administrative region of Guyana today. It may also refer to: * Essequibo River, the largest river in Guyana * Essequibo (colony), a former Dutch colony in what is now Guyana; * Esseq ...

, Paraná–

Paraguay Paraguay (; ), officially the Republic of Paraguay ( es, República del Paraguay, links=no; gn, Tavakuairetã Paraguái, links=si), is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to th ...

and

Parnaíba River The Parnaíba River ( pt, Rio Parnaíba) is a river in Brazil, which forms the border between the states of Maranhão and Piauí. Its main course is long and the Parnaíba River Basin covers .Ramos, T.P.A.; Ramos, R.T.C.; and Ramos, S.A.Q.A. (2 ...

basins. Depending on the species involved, these elongate fish reach a length of .

Species

There are currently 21 recognized species in this genus: * ''

Hemiodus amazonum ''Hemiodus'' is a genus of halftooths from South America with the greatest species richness in the Amazon Basin, but also found in the Orinoco, Essequibo, Paraná–Paraguay and Parnaíba River basins. Depending on the species involved, these e ...

'' ( Humboldt, 1821) * '' Hemiodus argenteus'' Pellegrin, 1909 * '' Hemiodus atranalis'' ( Fowler, 1940) * ''

Hemiodus goeldii ''Hemiodus'' is a genus of halftooths from South America with the greatest species richness in the Amazon Basin, but also found in the Orinoco, Essequibo, Paraná–Paraguay and Parnaíba River basins. Depending on the species involved, these e ...

Steindachner Franz Steindachner (11 November 1834 in Vienna – 10 December 1919 in Vienna) was an Austrian zoologist, ichthyologist, and herpetologist. He published over 200 papers on fishes and over 50 papers on reptiles and amphibians. Steindachner describ ...

, 1908 * '' Hemiodus gracilis'' Günther, 1864 * '' Hemiodus huraulti'' (

Géry Géry () is a commune in the Meuse department in Grand Est in north-eastern France. See also *Communes of the Meuse department The following is a list of the 499 communes of the Meuse department of France. The communes cooperate in the follo ...

, 1964) * '' Hemiodus immaculatus'' Kner, 1858 * ''

Hemiodus iratapuru ''Hemiodus'' is a genus of halftooths from South America with the greatest species richness in the Amazon Basin, but also found in the Orinoco, Essequibo, Paraná–Paraguay and Parnaíba River basins. Depending on the species involved, these e ...

'' Langeani & C. L. R. Moreira, 2013 Langeani, F. & Moreira, C.R. (2013): ''Hemiodus iratapuru'', a new species of Hemiodontidae from the Rio Jari, Amazon Basin, Brazil (Teleostei, Characiformes). ''Journal of Fish Biology, 82 (4): 1259–1268.'' * '' Hemiodus jatuarana'' Langeani, 2004 * '' Hemiodus langeanii'' Beltrão & Zuanon, 2012Beltrão, H. & Zuanon, J. (2012)
Hemiodus langeanii (Characiformes: Hemiodontidae), a new species from rio Amana, rio Maués-Açú drainage, Amazon basin, Brazil.
''Neotropical Ichthyology, 10 (2): 255-262.'' * '' Hemiodus microlepis'' Kner, 1858 * '' Hemiodus orthonops'' C. H. Eigenmann & C. H. Kennedy, 1903 * '' Hemiodus parnaguae'' C. H. Eigenmann &

Henn Henn is a both a surname and an Estonian masculine given name. Notable people with the surname include: ;As a given name: * Henn-Ants Kurg (1898–1943), Estonian military colonel and diplomat * Henn Pärn (born 1941), Estonian politician * ...

, 1916 * '' Hemiodus quadrimaculatus'' Pellegrin, 1909 (Barred hemiodus) * '' Hemiodus semitaeniatus'' Kner, 1858 (Halfline hemiodus) * '' Hemiodus sterni'' (

, 1964) * '' Hemiodus ternetzi'' G. S. Myers, 1927 * '' Hemiodus thayeria'' J. E. Böhlke, 1955 * '' Hemiodus tocantinensis'' Langeani, 1999 * '' Hemiodus unimaculatus'' (

Bloch Bloch is a surname of German origin. Notable people with this surname include: A–F * (1859-1914), French rabbi *Adele Bloch-Bauer (1881-1925), Austrian entrepreneur *Albert Bloch (1882–1961), American painter * (born 1972), German motor journal ...

, 1794) * '' Hemiodus vorderwinkleri'' (

, 1964)

References

Hemiodontidae Characiformes genera Taxa named by Johannes Peter Müller Fish of South America {{Characiformes-stub