''Hemiodus'' is a genus of halftooths from

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

with the greatest

species richness Species richness is the number of different species represented in an community (ecology), ecological community, landscape or region. Species richness is simply a count of species, and it does not take into account the Abundance (ecology), abunda ...

in the

Amazon Basin The Amazon basin is the part of South America drained by the Amazon River and its tributary, 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 ...

, 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 approximately 1 million km2, with 65% of it in Venezuela and 35% in Colombia. It is the List of rivers by discharge, f ...

, Essequibo, Paraná–

Paraguay Paraguay, officially the Republic of Paraguay, is a landlocked country in South America. It is bordered by Argentina to the Argentina–Paraguay border, south and southwest, Brazil to the Brazil–Paraguay border, east and northeast, and Boli ...

and

Parnaíba River The Parnaíba River ( ) 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. (2014). Ichthyofaun ...

basins. Depending on the species involved, these elongate fish reach a length of . Fossil remains are known from the

Middle Miocene The Middle Miocene is a sub-epoch of the Miocene epoch (geology), epoch made up of two Stage (stratigraphy), stages: the Langhian and Serravallian stages. The Middle Miocene is preceded by the Early Miocene. The sub-epoch lasted from 15.97 ± 0. ...

-aged

Pebas Formation The Pebas Formation is a stratigraphic unit#Lithostratigraphic units, lithostratigraphic unit of Miocene age, found in western Amazon rainforest, Amazonia. The geological formation, formation extends over , including parts of Brazil, Peru, Ecuador ...

of Peru.

Species

There are currently 21 recognized species in this genus: * '' Hemiodus amazonum'' ( Humboldt, 1821) * '' Hemiodus argenteus'' Pellegrin, 1909 * '' Hemiodus atranalis'' ( Fowler, 1940) * '' Hemiodus goeldii'' Steindachner, 1908 * '' Hemiodus gracilis'' Günther, 1864 * '' Hemiodus huraulti'' ( Géry, 1964) * '' Hemiodus immaculatus'' Kner, 1858 * '' Hemiodus iratapuru'' 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 name include: As a given name * Henn-Ants Kurg (1898–1943), Estonian military colonel and diplomat * Henn Pärn (born 1941), Estonian politician * Hen ...

, 1916 * '' Hemiodus quadrimaculatus'' Pellegrin, 1909 (Barred hemiodus) * '' Hemiodus semitaeniatus'' Kner, 1858 (Halfline hemiodus) * '' Hemiodus sterni'' ( Géry, 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 *Adele Bloch-Bauer (1881–1925), Austrian entrepreneur *Albert Bloch (1882–1961), American painter *Alexandre Bloch (1857–1919), French painter *Alfred Bloch ( ...

, 1794) * '' Hemiodus vorderwinkleri'' ( Géry, 1964)

References

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