Pterygoplichthyini 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 ...

catfish Catfish (or catfishes; order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the three largest species alive, ...

es (

order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of ...

Siluriformes) of the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

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 ...

. It includes two

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 ...

, ''

Pterygoplichthys ''Pterygoplichthys'', sometimes collectively known as janitor fish, is a genus of South American armored catfishes. These fish are commonly known as sailfin armoured catfish or sailfin plecs, especially in the aquarium trade. Etymology ''Pte ...

'' and the currently undescribed genus referred to as the ''Hemiancistrus annectens'' group, This group was earlier misspelled as Pterygoplichthini. Pterygoplichthyines are known from nearly the entire range of loricariids except for the

Guyanas The Guianas, sometimes called by the Spanish loan-word ''Guayanas'' (''Las Guayanas''), is a region in north-eastern South America which includes the following three territories: * French Guiana, an overseas department and region of France * ...

and coastal streams 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 ...

. although later work by the same authority, and his co-authors, placed this group among the genus ''

Hypostomus ''Hypostomus'' is a genus of catfish in the family Loricariidae. They are native to tropical and subtropical South America. '' H. plecostomus'' is the popular freshwater aquarium fish formerly known as ''Plecostomus plecostomus''. The taxonomic ...

''. Pterygoplichthyini is

sister A sister is a woman or a girl who shares one or more parents with another individual; a female sibling. The male counterpart is a brother. Although the term typically refers to a familial relationship, it is sometimes used endearingly to refer to ...

to the tribe

Ancistrini Ancistrini is a tribe of catfishes of the family Loricariidae. Most are restricted to tropical and subtropical South America, but there are also several genus (''Ancistrus'', ''Chaetostoma'', '' Hemiancistrus'' and '' Lasiancistrus'') in southern ...

, which shares the

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 ...

presence of an evertible patch of plates on the cheek. ''Pterygoplichthys'' and the ''H. annectens'' group differ most obviously in the number of dorsal fin rays (7 in the ''H. annectens'' group and 9+ in ''Pterygoplichthys''). The two genera are supported as sisters by only one derived characteristic: a modified stomach that is attached to the abdominal wall by a net of connective tissue. This modified stomach allows these fish to breathe air. The stomach is vascularized. A white net of connective tissue surrounds the organ, leaving a circular area in the middle of the stomach free; this connective tissue firmly holds the stomach to the body wall and is better developed in adults. It may also function as a hydrostatic organ, allowing the fish to remain buoyant midwater.

References

{{Taxonbar, from=Q1121516 Hypostominae Fish tribes Taxa named by Jonathan W. Armbruster