Cynodontidae, from

Ancient Greek Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...

κύων (''kúōn''), meaning "dog", and ὀδούς (''odoús''), meaning "tooth", also known as dogtooth

characins Characidae, the characids, is a family of freshwater subtropical and tropical fish belonging to the order Characiformes. They are found throughout much of Central and South America, including such major waterways as the Amazon and Orinoco Rivers ...

or vampire

tetra Tetra is the common name of many small freshwater characiform fishes. Tetras come from Africa, Central America, and South America, belonging to the biological families Characidae, Alestidae (the "African tetras"), Lepidarchidae, Lebiasi ...

s, are a

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

of predatory,

characiform Characiformes is an order of Actinopterygii, ray-finned fish, comprising the characins and their allies. Grouped in 18 recognized families, more than 2000 different species are described, including the well-known piranha and tetras.; Buckup P.A ...

freshwater

fishes A fish (: fish or fishes) is an aquatic, anamniotic, gill-bearing vertebrate animal with swimming fins and a hard skull, but lacking limbs with digits. Fish can be grouped into the more basal jawless fish and the more common jawed ...

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 ...

. This group is not very diverse, and includes only three

genera Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial s ...

and 8

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

. The largest species in this family ranges up to . They are characterized by an oblique mouth and very long distinct canines, 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 Many species of fish are caught by humans and consumed as food in virtually all regions around the world. Their meat has been an important dietary source of protein and other nutrients in the human diet. The English language does not have a s ...

, but are important in subsistence and commercial

fisheries Fishery can mean either the enterprise of raising or harvesting fish and other aquatic life or, more commonly, the site where such enterprise takes place ( a.k.a., fishing grounds). Commercial fisheries include wild fisheries and fish farm ...

. ''

Hydrolycus ''Hydrolycus'' is a genus of freshwater Actinopterygii, ray-finned fishes belonging to the Family (biology), family Cynodontidae, the dogtooth characins. These fishes are found in tropical South America, where found in the Amazon basin, Amazon an ...

'' are

game fish Game fish, sport fish or quarry refer to popular fish species pursued by recreational fishing, recreational fishers (typically angling, anglers), and can be freshwater fish, freshwater or saltwater fish. Game fish can be fish as food, eaten aft ...

, 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 and anglers are careful to follow ...

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

Taxonomy

This

monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...

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

Cynodon ''Cynodon'', from Ancient Greek κύων (''kúōn''), meaning "dog", and ὀδούς (''odoús''), meaning "tooth", 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 bei ...

'', four species of ''

'', 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 "unisp ...

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 l ...

''. These fish have been previously classified within

Characidae Characidae, the characids, is a family of freshwater subtropical and tropical fish belonging to the order Characiformes. They are found throughout much of Central and South America, including such major waterways as the Amazon and Orinoco Riv ...

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

sister groups 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 t ...

to each other; these two genera together have a sister group relationship to the genus ''Hydrolycus''. The subfamily Roestinae was previously placed in this family, but are now known to be more closely related to ''

Acestrorhynchus ''Acestrorhynchus'' ("needle jaw" ) is a genus of characiform fish found only in fresh water in South America, the sole genus in the subfamily Acestrorhynchinae. Their greatest diversity is in the Orinoco and Amazon basins. These fish have elonga ...

'', and are now placed in the

Acestrorhynchidae Acestrorhynchidae is a family of freshwater fish in the order Characiformes, found in South America. Members of this family are known as freshwater barracudas (not to be confused with the unrelated true barracudas of the Sphyraenidae) and bitin ...

Species

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

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 ...

Physical characteristics

Cynodontidae are elongated in shape with a silvery or grey colour and an upturned mouth. Some species have a hunchbacked appearance. The family names (both scientific and common) derive from the long and well-developed canines which are used to spear their prey, mainly other fish. Their

pectoral fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish aquatic locomotion, swim. Apart from the tail or caudal fin, fish fins have no direct connection with the vertebral column ...

s are also expanded. The maximum length reached is .

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

and Amazon basins, as well as the rivers of the

Guianas The Guianas, also spelled Guyanas or Guayanas, are a geographical region in north-eastern South America. Strictly, the term refers to the three Guianas: Guyana, Suriname, and French Guiana, formerly British Guiana, British, Surinam (Dutch colo ...

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

Paraná Paraná, Paranã or Parana may refer to: Geology * Paraná Basin, a sedimentary basin in South America Places In Argentina *Paraná, Entre Ríos, a city * Paraná Department, a part of Entre Ríos Province In Brazil *Paraná (state), a state ...

Paraguay River The Paraguay River (''Ysyry Paraguái'' in Guarani language, Guarani, ''Rio Paraguai'' in Portuguese language, Portuguese, ''Río Paraguay'' in Spanish language, Spanish) is a major river in south-central South America, running through Brazil, Bol ...

and

Uruguay River The Uruguay River ( ; ) 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 Mesopotamia from the other two countr ...

basins. Fossil teeth have been found in the

Magdalena River The Magdalena River (, ; 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 of its lower reaches, ...

basin and

Salta Salta () is the capital and largest city in the Provinces of Argentina, Argentine province of Salta Province, the same name. With a population of 618,375 according to the 2010 census, it is also the List of cities in Argentina, 7th most-populous ...

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

, where cynodontines are not currently found.

Relationship to humans

'' species are

, having been recently added to the

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

References