''Tometes'' 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 ...

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...

in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Serrasalmidae The Serrasalmidae (serrasalmids) are a family of characiform fishes, recently elevated to family status. It includes more than 90 species. The name means "serrated salmon family", which refers to the serrated keel running along the belly of these ...

found in fast-flowing rivers in northern

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

. Adults of all seven species in this genus are

phytophagous A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpar ...

, feeding primarily on aquatic plants in the family

Podostemaceae Podostemaceae (riverweed family), a family in the order Malpighiales, comprise about 50 genera and species of more or less thalloid aquatic herbs. Distribution and habitat They are found mostly in tropical and subtropical areas worldwide. Ma ...

. The genus name ''Tometes'' was coined in 1850 by

Valenciennes Valenciennes (, also , , ; nl, label=also Dutch, Valencijn; pcd, Valincyinnes or ; la, Valentianae) is a commune in the Nord department, Hauts-de-France, France. It lies on the Scheldt () river. Although the city and region experienced a s ...

in reference to the incisiform teeth. When the

type species In 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 species that contains the biological type specimen ...

of the genus, ''T. trilobatus'', was described in 1850, it was placed in

synonym A synonym is a word, morpheme, or phrase that means exactly or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are all ...

with ''Myleus setiger'', the type species of the genus ''

Myleus ''Myleus'' is a genus of serrasalmids from South America, where found in the Amazon, Orinoco and São Francisco basins, as well as river basin of the Guiana Shield.Ota, R.P., Röpke, C.P., Zuanon, J. & Jégu, M. (2013): Serrasalmidae. ''In'': Q ...

'', which is why ''Tometes'' and ''Myleus'' were considered to be the same genus for a long time. It was just later that the two genera were revalitated and other specimen could be categorized in the genus ''Tometes''.

Taxonomy

Even today the

taxonomic Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...

classification of the

is not an easy task. Many names are placed in

synonymy A synonym is a word, morpheme, or phrase that means exactly or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are all ...

due to a lack of information and insufficient data bases. It was not long ago when it was discovered that ''Tometes'' and ''

'' are two different genera but that ''Tometes'', ''Myleus'', ''

Mylesinus ''Mylesinus'' is a genus of serrasalmids from South America, where found in the eastern Amazon, Essequibo and Orinoco basins. They are rheophilic, typically found at rapids and mainly feed on Podostemaceae plants. Because of their habitat prefe ...

'' and ''

Ossubtus ''Ossubtus'' is a genus of fish in the family Serrasalmidae. It contains a single species, ''Ossubtus xinguense'', the parrot pacu or eaglebeak pacu, The species is endemic to rapids in the Xingu River basin in the Brazilian Amazon.Andrade, M.C., ...

'' share a

common ancestor Common descent is a concept in evolutionary biology applicable when one species is the ancestor of two or more species later in time. All living beings are in fact descendants of a unique ancestor commonly referred to as the last universal comm ...

. Typical characters of ''Tometes'' coincide with ''Mylesinus'' and ''Ossubtus'' specimen more than ''Myleus''. It is further known that ''Tometes'' live in sympatry with other reophilic Serrasalmidae. ''Tometes'' species are also not to be mistaken with

pacu Pacu () is a common name used to refer to several species of omnivorous South American freshwater serrasalmid fish that are related to the piranha. Pacu and piranha do not have similar teeth, the main difference being jaw alignment; piranha hav ...

s, a vegetarian fish, which is often sold as a vegetarian piranha in the corresponding countries. One can easily distinguish one from another by their very different composition of their dentition.

Description

Depending on the exact species, the maximum length of ''Tometes'' is between . They can weigh more than . The body color is generally gray or silvery, showing a brighter color at the bottom side. Their name was given due to their incisiform teeth, which are thicker and lower than in the other related genera. Also the teeth are placed side by side, are weakly attached to the jaw and are primarily used for cutting leaves. Sexually mature male of ''Tometes'' differ from females by an additional anal-fin lobe, an elongated

dorsal fin A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through conv ...

or a red pattern on the body.

Range, habitat and ecology

''T. ancylorhynchus'', ''T. kranponhah'' and ''T. siderocarajensis'' are found in clearwater rivers that originate in the Brazilian Shield ( Xingu 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 20 ...

— Araguaia basins), ''T. camunani'', ''T. lebaili'' and ''T. trilobatus'' are found in rivers of the eastern

Guiana Shield The Guiana Shield (french: Plateau des Guyanes, Bouclier guyanais; nl, Hoogland van Guyana, Guianaschild; pt, Planalto das Guianas, Escudo das Guianas; es, Escudo guayanés) is one of the three cratons of the South American Plate. It is a ...

(

Trombetas The Trombetas is a large river on the northern side of the Amazon River. Course The Trombetas is long, and is navigable by 500 ton vessels for a stretch of . The Trombetas river gives birth to very many rivers, including the Anamu river. It is ...

, Commewijne,

Mana According to Melanesian and Polynesian mythology, ''mana'' is a supernatural force that permeates the universe. Anyone or anything can have ''mana''. They believed it to be a cultivation or possession of energy and power, rather than being a ...

, Maroni,

Oyapock The Oyapock or Oiapoque (; ; ) is a long river in South America that forms most of the border between the French overseas department of French Guiana and the Brazilian state of Amapá. Course The Oyapock runs through the Guianan moist fores ...

, Amapá Grande and

Araguari Araguari is a municipality in western Minas Gerais state, Brazil. It is in the northern Triângulo Mineiro region, on the Jordão River, a tributary of the Paranaíba River, at an elevation between . The municipality of Araguari has an area of , w ...

basins), and ''T. makue'' is from the Rio Negro 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. These species all live in rapidly moving water with a rocky environment. A dense occurrence of ''Tometes'' larvae and juveniles in

rapids Rapids are sections of a river where the river bed has a relatively steep gradient, causing an increase in water velocity and turbulence. Rapids are hydrological features between a ''run'' (a smoothly flowing part of a stream) and a ''cascade''. ...

around

plants, the main food source of adult ''Tometes'', suggests that there is a positive rheotrophism (adaptability to fast-flowing water) in the larval stage. Unlike the strictly

adults, juveniles also feed on

invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...

s. Their association with Podostemaceae plants restricts their distributions, which makes them vulnerable to the loss of rapids by the introduction of

hydroelectric Hydroelectricity, or hydroelectric power, is electricity generated from hydropower (water power). Hydropower supplies one sixth of the world's electricity, almost 4500 TWh in 2020, which is more than all other renewable sources combined and ...

dams. In a cultural aspect

rheophilic A rheophile is an animal that prefers to live in fast-moving water. Examples of rheophilic animals Insects *Many aquatic insects living in riffles require current to survive. *''Epeorus sylvicola'', a rheophilic mayfly species ( Ephemeroptera) ...

serrasalmids (notably ''Tometes'', ''

Myloplus ''Myloplus'' is a genus of freshwater fish in the family Serrasalmidae found in tropical and subtropical South America, where they inhabit rivers and streams (both slow and fast-flowing). They are primarily herbivores, but also take some animal ...

'' and ''

'') are important in the tradition of local communities.

Species

There are currently 7 recognized species in this genus: * '' Tometes ancylorhynchus'' M. C. Andrade, Jégu & Giarizzo, 2016Andrade, M.C., Jégu, M. & Giarizzo, T. (2016): ''Tometes kranponhah'' and ''Tometes ancylorhynchus'' (Characiformes: Serrasalmidae), two new phytophagous serrasalmids, and the first ''Tometes'' species described from the Brazilian Shield. ''Journal of Fish Biology, 89 (1): 467-494.'' * '' Tometes camunani'' M. C. Andrade, Giarizzo & Jégu, 2013Andrade, M.C., Giarizzo, T. & Jégu, M. (2013): ''Tometes camunani'' (Characiformes: Serrasalmidae), a new species of phytophagous fish from the Guiana Shield, rio Trombetas basin, Brazil. ''Neotropical Ichthyology, 11 (2): 297-306.'' * '' Tometes kranponhah'' M. C. Andrade, Jégu & Giarizzo, 2016 * '' Tometes lebaili'' Jégu,

Keith Keith may refer to: People and fictional characters * Keith (given name), includes a list of people and fictional characters * Keith (surname) * Keith (singer), American singer James Keefer (born 1949) * Baron Keith, a line of Scottish barons ...

& Belmont-Jégu, 2002 * '' Tometes makue'' Jégu, G. M. Santos & Belmont-Jégu, 2002 * '' Tometes siderocarajensis'' Andrade et al., 2017Marcelo C. Andrade, Valéria N. Machado, Michel Jégu, Izeni P. Farias and Tommaso Giarrizzo (2017). A New Species of Tometes Valenciennes 1850 (Characiformes: Serrasalmidae) from Tocantins-Araguaia River Basin Based on Integrative Analysis of Molecular and Morphological Data. PLoS ONE 12(4): e0170053. * '' Tometes trilobatus''

, 1850

References

{{Taxonbar, from=Q6415779 Serrasalmidae Fish of South America