''Trichomycterus'' 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 ...

Trichomycteridae Trichomycteridae is a family of catfishes commonly known as pencil catfishes or parasitic catfishes. This family includes the candiru fish (''Vandellia cirrhosa''), feared by some people for its alleged habit of entering into the urethra of ...

, the largest genus of its family with over 170

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), ...

currently described. This genus is native to freshwater habitats in Central and

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 ...

. These fish are generally small, usually about in

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

, although the largest, '' T. rivulatus'', can reach more than twice this size. Species differ from one another primarily in body proportions, fin ray counts and colouration.Fernández, L. & Osinaga, K. (2006)
A New ''Trichomycterus'' (Siluriformes: Trichomycteridae) from Aguarague National Park of the Bolivian Preandean Region, with Comments on Relationships within of the Genus.
''Environmental Biology of Fishes, 75 (4): 385–393.'' Despite their relatively small size, some, such as '' T. punctulatus'', support fisheries and are important in the local cuisine.

Taxonomy

This genus is defined by the lack of specializations found in other trichomycterids and is certainly

polyphyletic A polyphyletic group is an assemblage that includes organisms with mixed evolutionary origin but does not include their most recent common ancestor. The term is often applied to groups that share similar features known as Homoplasy, homoplasies ...

.Alencar, A.R. & Costa, W.J.E.M. (2006)
''Trichomycterus pauciradiatus'', a new catfish species from the upper rio Paraná basin, southeastern Brazil (Siluriformes: Trichomycteridae).
''Zootaxa, 1269: 43–49.''Wosiacki, W.B. (2005)
A new species of ''Trichomycterus'' (Siluriformes: Trichomycteridae) from south Brazil and redescription of ''T. iheringi'' (Eigenmann).
''Zootaxa, 1040: 49–64.'' Although known to contain many species, ''Trichomycterus'' is poorly known with many of the known species based on brief descriptions. Many species have been described recently and many more are waiting to be described.Lima, S.M.Q., Lazzarotto, H. & Costa, W.J.E.M. (2008)
A new species of ''Trichomycterus'' (Siluriformes: Trichomycteridae) from lagoa Feia drainage, southeastern Brazil.
''Neotropical Ichthyology, 6 (3): 315–322.'' Some authors have tentatively defined putative

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 ...

assemblages within the genus ''Trichomycterus'' based on the possession of unique morphological features. The ''Trichomycterus brasiliensis'' species-complex includes ''T. brasiliensis'', ''T. iheringi'', ''T. maracaya'', ''T. mimonha'', ''T. pirabitira'', ''T. potschi'', ''T. vermiculatus'' and several undescribed species apparently

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 the main river basins draining the Brazilian Shield.Bockmann, F.A. & Sazima, I. (2004)
''Trichomycterus maracaya'', a new catfish from the upper rio Paraná, southeastern Brazil (Siluriformes: Trichomycteridae), with notes on the ''T. brasiliensis'' species-complex.
''Neotropical Ichthyology, 2 (2): 61–74.'' However, an assemblage of species from south and southeastern Brazil is also supported that includes ''T. araxa'',Costa, W.J.E.M., Mattos, J.L.O., Sampaio, W.M.S, Giongo, P., de Almeida, F.B. & Katz, A.M. (2022)
Phylogenetic relationships of a new catfish of the genus ''Trichomycterus'' (Siluriformes, Trichomycteridae) from the Brazilian Cerrado, and the role of Cenozoic events in the diversification of mountain catfishes.
''Zoosystematics and Evolution, 98 (1): 151–164.'' ''T. castroi'', ''T. davisi'', ''T. guaraquessaba'', ''T. immaculatus'', ''T. itatiayae'', ''T. mboycy'', ''T. mirissumba'', ''T. naipi'', ''T. nigricans'', ''T. papilliferus'', ''T. plumbeus'', ''T. stawiarski'', ''T. taroba'', ''T. triguttatus'' and ''T. zonatus'', ''T. aguarague'', ''T. alterus'', ''T. belensis'', ''T. boylei'' and ''T. ramosus'' also form a diagnosable species assemblage.

Distribution and habitat

Species of ''Trichomycterus'' inhabit a diversity of habitats throughout

South South is one of the cardinal directions or compass points. The direction is the opposite of north and is perpendicular to both west and east. Etymology The word ''south'' comes from Old English ''sūþ'', from earlier Proto-Germanic ''*sunþa ...

and

Central America Central America is a subregion of North America. Its political boundaries are defined as bordering Mexico to the north, Colombia to the southeast, the Caribbean to the east, and the Pacific Ocean to the southwest. Central America is usually ...

from

Costa Rica Costa Rica, officially the Republic of Costa Rica, is a country in Central America. It borders Nicaragua to the north, the Caribbean Sea to the northeast, Panama to the southeast, and the Pacific Ocean to the southwest, as well as Maritime bo ...

in the north to

Patagonia Patagonia () is a geographical region that includes parts of Argentina and Chile at the southern end of South America. The region includes the southern section of the Andes mountain chain with lakes, fjords, temperate rainforests, and glaciers ...

in the south and from lowland Atlantic rainforest in the east to

Andean The Andes ( ), Andes Mountains or Andean Mountain Range (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long and wide (widest between 18°S ...

highland streams in the west. They are, together with ''

Astroblepus ''Astroblepus'' is a genus of fish in the family Astroblepidae found in South America and Panama. This genus is the only member of its family. These catfishes are primarily found in torrential streams in the Andean area. ''Astroblepus pholeter'' ...

'' and ''

Orestias Orestias (), later refounded by Hadrian as Adrianople (Greek: Άδριανούπολις), was an ancient Greek settlement next to the Evros river in Thrace, near or at the site of present-day Edirne, and close to the current border between Turk ...

'', among the very few native fish genera at high altitude in the Andes and in some places, for example certain high-elevation localities in western

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 ...

, ''Trichomycterus'' are the only fishes.Fernández, L. & Vari, R.P. (2004)
New Species of ''Trichomycterus'' from Midelevation Localities of Northwestern Argentina (Siluriformes: Trichomycteridae).
''Copeia, 2004 (4): 876–882.'' About 60 nominal species are

to the river basins draining the Andes and hills of the Guianan Shield and about 30 species are endemic to river basins draining the Brazilian Shield.Alencar, A.R. & Costa, W.J.E.M. (2004)
Description of two new species of the catfish genus ''Trichomycterus'' from southeastern Brazil (Siluriformes: Trichomycteridae).
''Zootaxa, 744: 1–8.'' Despite the broad distribution of the genus, most species have limited distributions and usually are restricted to only one river.Lima, S.M.Q. & Costa, W.J.E.M. (2004)
''Trichomycterus giganteus'' (Siluriformes: Loricarioidea: Trichomycteridae): a new catfish from the Rio Guandu basin, southeastern Brazil.
''Zootaxa, 761: 1–6.'' Wide-ranging species are most likely complexes of species that are difficult to differentiate, such as the ''T. brasiliensis'' species-complex. ''Trichomycterus gorgona'', from a small stream on Gorgona Island located west of the

Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is bounded by the cont ...

coast of

Colombia Colombia, officially the Republic of Colombia, is a country primarily located in South America with Insular region of Colombia, insular regions in North America. The Colombian mainland is bordered by the Caribbean Sea to the north, Venezuel ...

, is the first known trichomycterid to be endemic to an offshore island.Fernández, L. & Schaefer, S.A. (2005)
New ''Trichomycterus'' (Siluriformes: Trichomycteridae) from an Offshore Island of Colombia.
''Copeia, 2005 (1): 68–76.'' Many species are

troglobitic A troglobite (or, formally, troglobiont) is an animal species, or population of a species, strictly bound to underground habitats, such as caves. These are separate from species that mainly live in above-ground habitats but are also able to live u ...

Species

There are currently 174 recognized species in this genus:

References

{{Taxonbar, from=Q584577 Catfish genera Fish of Central America Catfish of South America Freshwater fish genera Taxa named by Achille Valenciennes Trichomycteridae