Rhinelepini is a

tribe The term tribe is used in many different contexts to refer to a category of human social group. The predominant worldwide usage of the term in English is in the discipline of anthropology. This definition is contested, in part due to confl ...

of fishes in the subfamily

Hypostominae The Hypostominae are a subfamily of catfishes of the family Loricariidae. Most members are restricted to tropical and subtropical South America, but there are also several species (in genera ''Ancistrus'', ''Chaetostoma'', '' Lasiancistrus'', '' ...

of the armored suckermouth catfish family

Loricariidae The Loricariidae is the largest family of catfish (order Siluriformes), with 92 genera and just over 680 species. Loricariids originate from freshwater habitats of Costa Rica, Panama, and tropical and subtropical South America. These fish are n ...

Taxonomy

This tribe is a well diagnosed

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 ...

group currently containing three

genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial ...

: '' Pogonopoma'', ''

Pseudorinelepis ''Pseudorinelepis genibarbis'' is a species of armored catfish native to Brazil, Peru and Ecuador where it is found in the Amazon basin. Taxonomy ''Pseudorinelepis'' is one of three genera contained in the tribe Rhinelepini, one of the tribes ...

'', and ''

Rhinelepis ''Rhinelepis'' is a genus of South American armored catfish. Species There are currently two recognized species in this genus: * ''Rhinelepis aspera'' Spix & Agassiz, 1829 * ''Rhinelepis strigosa ''Rhinelepis strigosa'' is a species of ar ...

''. When the tribe was first described, ''Pogonopomoides'' was a valid genus, but it is now a

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 al ...

of ''Pogonopoma''. ''Pseudorinelepis'' is the most

basal Basal or basilar is a term meaning ''base'', ''bottom'', or ''minimum''. Science * Basal (anatomy), an anatomical term of location for features associated with the base of an organism or structure * Basal (medicine), a minimal level that is nec ...

, and ''Rhinelepis'' and ''Pogonopoma'' are more

derived Derive may refer to: * Derive (computer algebra system), a commercial system made by Texas Instruments * ''Dérive'' (magazine), an Austrian science magazine on urbanism *Dérive, a psychogeographical concept See also * *Derivation (disambiguatio ...

sister groups In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and t ...

Appearance and anatomy

Rhinelepini species are generally medium to large-sized Loricariids. Rhinelepini species are unique among Loricariidae for having a normal, circular

iris Iris most often refers to: *Iris (anatomy), part of the eye *Iris (mythology), a Greek goddess * ''Iris'' (plant), a genus of flowering plants * Iris (color), an ambiguous color term Iris or IRIS may also refer to: Arts and media Fictional ent ...

as opposed to the bilobed, omega iris. These species end to have relatively thick armor plates on their bodies. In

Iquitos Iquitos (; ) is the capital city of Peru's Maynas Province and Loreto Region. It is the largest metropolis in the Peruvian Amazon, east of the Andes, as well as the ninth-most populous city of Peru. Iquitos is the largest city in the world tha ...

Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = Seal (emblem), National seal , national_motto = "Fi ...

, '' Pseudorinelepis genibarbis'' is known as ''carachama sin costilla'', which actually means "Loricariid without ribs"; this refers to the trait that it shares with other Rhinelepini catfish; members of this tribe do not have ribs past the sixth vertebra. One of the characters that binds this group together is a large U-shaped

diverticulum In medicine or biology, a diverticulum is an outpouching of a hollow (or a fluid-filled) structure in the body. Depending upon which layers of the structure are involved, diverticula are described as being either true or false. In medicine, t ...

of the digestive tract; this is always filled with air. The first part of the diverticulum is modified from the

esophagus The esophagus (American English) or oesophagus (British English; both ), non-technically known also as the food pipe or gullet, is an organ in vertebrates through which food passes, aided by peristaltic contractions, from the pharynx to the ...

and consists of thick musculature; this passes a short distance before reaching the second, main, U-shaped part of the diverticulum. In ''Rhinelepis'' and ''Pseudorinelepis'', the diverticulum functions as an accessory respiratory organ. In ''Rhinelepis'', the diverticulum is more attached to the abdominal wall and the interior of the diverticulum is more textured. In ''Pogonopoma'', the diverticulum is similar to a

swim bladder The swim bladder, gas bladder, fish maw, or air bladder is an internal gas-filled organ that contributes to the ability of many bony fish (but not cartilaginous fish) to control their buoyancy, and thus to stay at their current water depth w ...

and may be used as a hydrostatic organ; the first part of the diverticulum is greatly reduced and the second part is larger and has a smooth interior surface and less vascularized.

Distribution

The tribe Rhinelepini has an interesting biogeography and reveal information about the aquatic systems of

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 souther ...

. There is a split between the species that inhabit

Amazon Amazon most often refers to: * Amazons, a tribe of female warriors in Greek mythology * Amazon rainforest, a rainforest covering most of the Amazon basin * Amazon River, in South America * Amazon (company), an American multinational technolog ...

and those that inhabit the eastern river systems. ''Pseudorinelepis'', the most basal group, is found only in the Amazon basin. ''Pogonopoma'', is found in the

Mucuri Mucuri is a city in the state of Bahia in Brazil. The estimated population in 2020 is 42,251 inhabitants. It is the southernmost city in Bahia as well as Brazil's Northeast region, and the only one from that state to border Espírito Santo. The ...

Paraíba do Sul The Paraíba do Sul (), or simply termed Paraíba, is a river in southeast Brazil. It flows west to northeast from its farthest source at the source of the river Paraitinga to the sea near Campos dos Goytacazes. The river receives its name whe ...

, and

Uruguay River The Uruguay River ( es, Río Uruguay, ; pt, Rio Uruguai, ) is a major river in South America. It flows from north to south and forms parts of the boundaries of Brazil, Argentina, and Uruguay, separating some of the Argentine provinces of La M ...

systems in southeastern

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

. ''Rhinelepis'' is found in

São Francisco River The São Francisco River (, ) is a large river in Brazil. With a length of , it is the longest river that runs entirely in Brazilian territory, and the fourth longest in South America and overall in Brazil (after the Amazon, the Paraná and t ...

and

Paraná River The Paraná River ( es, Río Paraná, links=no , pt, Rio Paraná, gn, Ysyry Parana) is a river in south-central South America, running through Brazil, Paraguay, and Argentina for some ."Parana River". Encyclopædia Britannica. Encyclopædia Br ...

. It is also thought to have spread through to the Paraíba by a sharing of its headwaters with the Paraná in the past, which eventually got separated into two basins. The oldest group, ''Pseudorinelepis'', inhabits the Amazon area, while the distribution of the newer, more derived groups occurs in Southern Brazil, which is comparatively older.

References

External links

* - Contains excerpts from the paper about the Rhinelepis group {{Taxonbar, from=Q2148100 Hypostominae Fish of South America Taxa named by Jonathan W. Armbruster