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 use of the term in English is in the discipline of anthropology. The definition is contested, in part due to conflict ...

catfish Catfish (or catfishes; order (biology), order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Catfish are common name, named for their prominent barbel (anatomy), barbels, which resemble a cat's whiskers, though not ...

es (

order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...

Siluriformes) of 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 ...

Loricariidae Loricariidae is the largest family (biology), family of catfish (order Siluriformes), with over 90 genus, genera and just over 680 species. Loricariids originate from freshwater habitats of Costa Rica, Panama, and tropical and subtropical South A ...

. It includes two

genera Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial s ...

, ''

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

'' 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, also spelled Guyanas or Guayanas, are a geographical region in north-eastern South America. Strictly, the term refers to the three Guianas: Guyana, Suriname, and French Guiana, formerly British, Dutch, and French Guiana respectiv ...

and coastal streams in southeastern

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

. 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 s ...

''. Pterygoplichthyini is

sister A sister is a woman or a girl who shares parents or a parent 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 ref ...

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 southe ...

, which shares the derived 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