''Hydrolycus'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of large

dogtooth characin Cynodontidae, also known as dogtooth characins or vampire tetras, are a family of predatory, characiform freshwater fishes from South America. This group is not very diverse, and includes only five genera and 14 species. Most of what is known abo ...

s from

tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...

South America, where found in the

Amazon Amazon most often refers to: * Amazons, a tribe of female warriors in Greek mythology * Amazon rainforest, a rainforest covering most of the Amazon basin * Amazon River, in South America * Amazon (company), an American multinational technology c ...

and

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 ...

basins, as well as rivers of the

Guianas The Guianas, sometimes called by the Spanish loan-word ''Guayanas'' (''Las Guayanas''), is a region in north-eastern South America which includes the following three territories: * French Guiana, an overseas department and region of France * ...

. The genus includes the largest dogtooth characins, reaching up to in length. They have long, pointed teeth (shorter and less extreme in ''H. wallacei'') used for spearing their prey, generally smaller fish. In a study of the stomachs of 45 individuals, most were empty, but among the remaining the prey fish were 15–50% of the length ''Hydrolycus'' itself. In 1999 two new species were described, the first in this genus in 158 years.

Species

There are currently four described

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

. * '' Hydrolycus armatus'' (

Jardine Jardine is a surname. Notable people with the surname include: * Al Jardine (born 1942), member of the Beach Boys * Alexander Jardine (Medal of Honor) (1874–1949), American Medal of Honor recipient * Antonio Jardine (born 1988), NCAA college bas ...

, 1841) (Payara) * ''

Hydrolycus scomberoides The payara, ''Hydrolycus scomberoides'', is a species of dogtooth tetra. This predatory fish is found in the Amazon Basin in tropical South America.SeriouslyFish: Hydrolycus scomberoides.' Retrieved 31 October 2015. It was the first of four sp ...

'' (

G. Cuvier Jean Léopold Nicolas Frédéric, Baron Cuvier (; 23 August 1769 – 13 May 1832), known as Georges Cuvier, was a French naturalist and zoologist, sometimes referred to as the "founding father of paleontology". Cuvier was a major figure in nat ...

, 1819) (Payara) * ''

Hydrolycus tatauaia ''Hydrolycus tatauaia'' is a species of dogtooth characin found in the Amazon, Orinoco and Essequibo basins in tropical South America. Adults mainly occur in deep and/or fast-flowing rivers. It is migratory, moving upstream to breed in November� ...

'' Toledo-Piza, Menezes & dos Santos, 1999 * ''

Hydrolycus wallacei ''Hydrolycus'' is a genus of large dogtooth characins from tropical South America, where found in the Amazon and Orinoco basins, as well as rivers of the Guianas. The genus includes the largest dogtooth characins, reaching up to in length. They ...

'' Toledo-Piza, Menezes & dos Santos, 1999

References

Cynodontidae Taxa named by Johannes Peter Müller Taxa named by Franz Hermann Troschel Freshwater fish of South America {{Characiformes-stub