''Acnodon normani'', the sheep-pacu, is a species of freshwater

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of sk ...

belonging to the

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 ...

Serrasalmidae The Serrasalmidae (serrasalmids) are a family of characiform fishes native to freshwater habitats of South America. They include more than 90 species. The name means "serrated salmon family", which refers to the serrated keel running along the ...

, which includes the pacus and piranhas. This species is found in the Amazon River basin of Brazil.

Taxonomy

''Acnodon normani'' was first formally described in 1951 by the American ichthyologist William Alonzo Gosline with its type locality given as the Rio Santa Teresa, a western tributary of the upper Rio Tocantins in Goias State, Brazil. This species is classified in the genus ''

Acnodon ''Acnodon'' is a genus of serrasalmids found in 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 ...

'' which belongs to the

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end botanical subfamily names with "-oideae", and zo ...

Myleinae in the family Serrasalmidae which is classified in the

suborder Order () is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and recognized ...

Characoidei of the

order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...

Characiformes Characiformes is an order of 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.: "Relationsh ...

Etymology

''Acnodon normani'' is classified in the genus ''Acnodon'', a name which prefixies ''a-'', meaning without, onto ''knodon'', which means "the projecting teeth on a hunting spear", an allusion to the mistaken perception that the

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

of the genus, '' A. oligacanthus'', does not have a spine in front of its

dorsal fin A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...

, it actually does but it is very small. The

Specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

honors of ichthyologist J. R. (John Roxborough) Norman, of the

British Museum of Natural History The Natural History Museum in London is a museum that exhibits a vast range of specimens from various segments of natural history. It is one of three major museums on Exhibition Road in South Kensington, the others being the Science Museum (Lo ...

, in recognition of his "excellent work" on the serrasalmids, among the other fish groups he studied.

Description

''Acnodon normani'' can be distinguished from ''A. oligacanthus'' in the possession odf a more acute snout and the lower jaw being shorter than the upper jaw. The premaxillary teeth of ''A. normani'' are very widely separated, to a greater extent than in any related species. This ish has silvery flanks with bluish stripes running down from the back to thge lateral line. The membrane of the

is dusky and the

caudal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported only ...

has a dusky margin. The sheep pacu has a maximum published

total length Fish measurement is the measuring of individual fish and various parts of their anatomies, for data used in many areas of ichthyology, including taxonomy and fishery biology. Overall length Standard length (SL) is the length of a fish measured f ...

of and a maximum published weight of .

Distribution

''Acnodon normani'' is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to Brazil where it is known from the Xingu and Tocantins- Araguaia river basins in states of

Mato Grosso Mato Grosso ( – ) is one of the states of Brazil, the List of Brazilian states by area, third largest by area, located in the Central-West Region, Brazil, Central-West region. The state has 1.66% of the Brazilian population and is responsible ...

Pará Pará () is a Federative units of Brazil, state of Brazil, located in northern Brazil and traversed by the lower Amazon River. It borders the Brazilian states of Amapá, Maranhão, Tocantins (state), Tocantins, Mato Grosso, Amazonas (Brazilian st ...

and

Tocantins Tocantins () is one of the 26 states of Brazil. It is the newest state, formed in 1988 and encompassing what had formerly been the northern two-fifths of the state of Goiás. Tocantins covers and had an estimated population of 1,496,880 in 2014 ...

. Theare are two records of this fish from the

Tapajós The Tapajós ( ) is a river in Brazil. It runs through the Amazon Rainforest and is a major tributary of the Amazon River. When combined with the Juruena River, the Tapajós is approximately long. Prior to a drastic increase in illegal gold mi ...

river system but these need confirmation.

References

*Géry, J., 1977. Characoids of the world. Neptune City; Reigate : T.F.H.

tc. TC, T.C., Tc, Tc, tc, tC, or .tc may refer to: Arts and entertainment Film and television * Theodore "T.C." Calvin, a character on the TV series '' Magnum, P.I.'' and its reboot * Tom Caron, American television host for New England Sports Netw ...

672 p. : ill. (chiefly col.); 23 cm. {{Taxonbar, from=Q5809306

normani Normani Kordei Hamilton ( ; born May 31, 1996), known mononymously as Normani, is an American singer. She first became known as a member of the girl group Fifth Harmony, which became one of the best-selling girl groups of all time. While in t ...

Fish of the Amazon basin Fish of the Tocantins River basin Taxa named by William Alonzo Gosline III Fish described in 1951