''Trichomycterus'' 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 ...

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 hum ...

, the largest genus of its family with over 170

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

currently described. This genus is native to freshwater habitats in

Central Central is an adjective usually referring to being in the center of some place or (mathematical) object. Central may also refer to: Directions and generalised locations * Central Africa, a region in the centre of Africa continent, also known as ...

and

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 ...

. These fish are generally small, usually about in

standard length Fish measurement is the measuring of individual fish and various parts of their anatomies. These data are used in many areas of ichthyology, including taxonomy and fisheries biology. Overall length * Standard length (SL) is the length of a fish m ...

, 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 of organisms or other evolving elements that is of mixed evolutionary origin. The term is often applied to groups that share similar features known as homoplasies, which are explained as a result of converg ...

.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 cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...

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 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 found elsew ...

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 Points of the compass, compass points. The direction is the opposite of north and is perpendicular to both east and west. Etymology The word ''south'' comes from Old English ''sūþ'', from earlier Pro ...

and

Central America Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. ...

from

Costa Rica Costa Rica (, ; ; literally "Rich Coast"), officially the Republic of Costa Rica ( es, República de Costa Rica), is a country in the Central American region of North America, bordered by Nicaragua to the north, the Caribbean Sea to the no ...

in the north to

Patagonia Patagonia () refers to a geographical region that encompasses the southern end of South America, governed by Argentina and Chile. The region comprises the southern section of the Andes Mountains with lakes, fjords, temperate rainforests, and gl ...

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

Andean The Andes, Andes Mountains or Andean Mountains (; ) are the List of mountain ranges#Mountain ranges by length, longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range i ...

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 ( el, Ὀρεστιάς) was an ancient Greek settlement next to the Maritsa (or Evros) river, near or at the site of present-day Edirne, and close to the current border between Turkey and Greece. Legends claim that Orestias was founded ...

'', 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 ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

, ''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 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 ...

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 definition, to Antarctica) in the south, and is bounded by the continen ...

coast of

Colombia Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pacific Ocean. The Colombian mainland is bordered by the Car ...

, 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 Fish of South America Freshwater fish genera Taxa named by Achille Valenciennes Trichomycteridae