Cynodontinae is a subfamily of

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 ...

and subtropical South American fishes of the family

Cynodontidae 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 ...

. They are characterized by an oblique mouth and very long distinct

canines Canine may refer to: Zoology and anatomy * a dog-like Canid animal in the subfamily Caninae ** ''Canis'', a genus including dogs, wolves, coyotes, and jackals ** Dog, the domestic dog * Canine tooth, in mammalian oral anatomy People with the surn ...

, which are used to capture and stab their prey, other fish that can be up to half the length of the cynodontine itself. They are not prized as

food fish Food is any substance consumed by an organism for nutritional support. Food is usually of plant, animal, or fungal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals. The substance is inges ...

, but are important in subsistence and commercial fisheries. '' Hydrolycus'' are

game fish Game fish, sport fish or quarry refer to popular fish pursued by recreational anglers, and can be freshwater or saltwater fish. Game fish can be eaten after being caught, or released after capture. Some game fish are also targeted commercia ...

, having been recently added to the

International Game Fish Association The International Game Fish Association (''IGFA'') is the leading authority on angling pursuits and the keeper of the most current World Record fishing catches by fish categories. Fishermen who are sport fishers are careful to follow their string ...

in the fly and rod class. Cynodontid fish are also sometimes housed in aquaria.

Taxonomy

This

monophyletic In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic ...

subfamily contains only a few species: three species of ''

Cynodon ''Cynodon'' is a genus of plants in the grass family. It is native to warm temperate to tropical regions of the Old World, as well as being cultivated and naturalized in the New World and on many oceanic islands. The genus name comes from G ...

'', four speciecs of '' Hydrolycus'', and one species in the

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

genus ''Rhaphiodon'', ''

Rhaphiodon vulpinus The biara (''Rhaphiodon vulpinus'') is a South American piscivorous fish in the dogtooth characin family. It belongs to the monotypic genus ''Rhaphiodon'', although some minor differences in morphometrics and colour are known from across its lar ...

''. These fish have been previously classified within

Characidae Characidae, the characids or characins is a family of freshwater subtropical and tropical fish, belonging to the order Characiformes. The name "characins" is the historical one, but scientists today tend to prefer "characids" to reflect their s ...

. ''Rhaphiodon'' and ''Cynodon'' are

sister group In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

s to each other; these two genera together have a sister group relationship to the genus ''Hydrolycus''.

Distribution and habitat

Cynodontinae species are found throughout 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 wo ...

and

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 Boli ...

s, as well as the 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 * ...

. Of the cynodontines, ''R. vulpinus'' has the greatest distribution, including the Paraná-

Paraguay River The Paraguay River (Río Paraguay in Spanish, Rio Paraguai in Portuguese, Ysyry Paraguái in Guarani) is a major river in south-central South America, running through Brazil, Bolivia, Paraguay and Argentina. It flows about from its headwaters in ...

and

Uruguay River The Uruguay River ( es, Río Uruguay, ; pt, Rio Uruguai, ) is a major river in South America. It flows from north to south and forms parts of the boundaries of Brazil, Argentina, and Uruguay, separating some of the Argentine provinces of La M ...

basins. Fossil teeth have been found in the

Magdalena River The Magdalena River ( es, Río Magdalena, ; less commonly ) is the main river of Colombia, flowing northward about through the western half of the country. It takes its name from the biblical figure Mary Magdalene. It is navigable through much o ...

basin and

Salta Salta () is the capital and largest city in the Argentine province of the same name. With a population of 618,375 according to the 2010 census, it is also the 7th most-populous city in Argentina. The city serves as the cultural and economic ce ...

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, t ...

, where cynodontines are not currently found. These fish live in mid- to surface-water levels in rivers, flooded forests, and lakes.

Appearance and anatomy

Cynodontines are distinguished by their oblique mouth and highly developed pair of

dentary In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...

canine teeth In mammalian oral anatomy, the canine teeth, also called cuspids, dog teeth, or (in the context of the upper jaw) fangs, eye teeth, vampire teeth, or vampire fangs, are the relatively long, pointed teeth. They can appear more flattened however ...

. These fish can get relatively large; ''Hydrolycus'' species can reach .

Species

''Hydrolycus'' species here are ordered based on their relationships from the most

basal Basal or basilar is a term meaning ''base'', ''bottom'', or ''minimum''. Science * Basal (anatomy), an anatomical term of location for features associated with the base of an organism or structure * Basal (medicine), a minimal level that is nec ...

to the most

apomorphic In phylogenetics, an apomorphy (or derived trait) is a novel character or character state that has evolved from its ancestral form (or plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to have ...

based on sister group relationships when possible. Descriptions and dates based on

ITIS The Integrated Taxonomic Information System (ITIS) is an American partnership of federal agencies designed to provide consistent and reliable information on the taxonomy of biological species. ITIS was originally formed in 1996 as an interagenc ...

. ''Rhaphiodon'' Agassiz in Spix and Agassiz, 1829 *''

'' Agassiz in Spix and Agassiz, 1829 ''

'' Agassiz, 1829 *'' Cynodon gibbus'' (Agassiz, 1829) *'' Cynodon meionactis'' Géry, Le Bail and Keith, 1999 *'' Cynodon septenarius'' Toledo-Piza, 2000 '' Hydrolycus'' Müller and Troschel, 1844 *''

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 and dos Santos, 1999 *''

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 ...

'' (Cuvier, 1819) *'' Hydrolycus armatus'' (Jardine and Schomburgk in Schomburgk, 1841) *''

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 and dos Santos, 1999

References

{{Taxonbar, from=Q14933235 Cynodontidae Fish of South America Fish subfamilies