''Tometes'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

fish A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...

in 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 ...

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 considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

. Adults of all seven species in this genus are

phytophagous A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet (nutrition), diet. These more broadly also encompass an ...

, 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 ...

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

Valenciennes Valenciennes (, also , , ; ; or ; ) is a communes of France, commune in the Nord (French department), Nord Departments of France, department, Hauts-de-France, France. It lies on the Scheldt () river. Although the city and region experienced ...

in reference to the incisiform teeth. When 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, ''T. trilobatus'', was described in 1850, it was placed in

synonym A synonym is a word, morpheme, or phrase that means precisely 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 a ...

with ''Myleus setiger'', the type species of the genus '' Myleus'', 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 280px, Generalized scheme of taxonomy Taxonomy is a practice and science concerned with classification or categorization. Typically, there are two parts to it: the development of an underlying scheme of classes (a taxonomy) and the allocation ...

classification of the

is not an easy task. Many names are placed in

synonymy A synonym is a word, morpheme, or phrase that means precisely 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 a ...

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

'' 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. According to modern evolutionary biology, all living beings could be descendants of a unique ancestor commonl ...

. 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 Serrasalmidae, serrasalmid fish related to piranhas. Pacu and piranha do not have similar teeth, the main difference being jaw alignment; piranha ...

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 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 ...

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 2014 ...

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

Guiana Shield The Guiana Shield (; ; ; ) is one of the three cratons of the South American Plate. It is a 1.7 billion-year-old Precambrian geological formation in northeast South America that forms a portion of the northern coast. The higher elevations on ...

( Trombetas, Commewijne,

Mana Mana may refer to: Religion and mythology * Mana (Oceanian cultures), the spiritual life force energy or healing power that permeates the universe in Melanesian and Polynesian mythology * Mana (food), archaic name for manna, an edible substance m ...

, 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 for ...

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

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 stream gradient, gradient, causing an increase in water velocity and turbulence. Flow, gradient, constriction, and obstacles are four factors that are needed for a rapid t ...

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 animals that neither develop nor retain a vertebral column (commonly known as a ''spine'' or ''backbone''), which evolved from the notochord. It is a paraphyletic grouping including all animals excluding the chordata, chordate s ...

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 generation, electricity generated from hydropower (water power). Hydropower supplies 15% of the world's electricity, almost 4,210 TWh in 2023, which is more than all other Renewable energ ...

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'' 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 & 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