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 confli ...

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 not ...

Taxonomy

This tribe is a well diagnosed monophyletic group currently containing three genera: '' Pogonopoma'', '' Pseudorinelepis'', and '' Rhinelepis''. When the tribe was first described, ''Pogonopomoides'' was a valid genus, but it is now a synonym of ''Pogonopoma''. ''Pseudorinelepis'' is the most basal, 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,

Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = National seal , national_motto = "Firm and Happy f ...

, '' 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 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 ...

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 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 sout ...

. 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

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, Paraíba do Sul, 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 and Paraná River. 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