The Copionodontinae are a

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end botanical subfamily names with "-oideae", and zo ...

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 Siluriformes) of the family

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 ...

. 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 ...

, '' Copionodon'' and '' Glaphyropoma''.

Classification

Copionodontines are remarkably primitive in body form, and lack many of the

synapomorphies In phylogenetics, an apomorphy (or derived trait) is a novel character or character state that has evolved from its ancestral form (or plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to ...

previously used to diagnose the family Trichomycteridae. Little doubt exists that the Copionodontinae form a

monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...

group, diagnosed by several unambiguous synapomorphies, including a unique

dentition Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, it is the characteristic arrangement, kind, and number of teeth in a given species at a given age. That is, the number, type, and morpho-physiology ...

composed of spatulate teeth not seen anywhere else in the Trichomycteridae. A few characters also support the genera ''Copionodon'' and ''Glaphyropoma'' as monophyletic subunits.

Distribution and ecology

Copionodontines occur exclusively in the

Chapada Diamantina Chapada Diamantina (; Portuguese language, Portuguese for the "Diamond Plateau") is a region of Bahia state, in the Northeast Region, Brazil, Northeast of Brazil. This mountain range is known as “Serra do Espinhaço,” in Minas Gerais state, ...

; though the plateau is drained by four river basins, so far, these fish are exclusively found in drainages associated with the

Paraguaçu River The Paraguaçu River () is a river in Bahia state, located in eastern Brazil. It runs from the Chapada Diamantina highlands of central Bahia to its mouth at the Baía de Todos os Santos. The Paraguaçu River is the largest river entirely within B ...

. Copionodontines occupy the upper reaches of fast-flowing streams on rocky beds, often with tiny or no water flow in the dry season. Fish tend to concentrate on quiet, deep pools, though some individuals lodge in narrow rock crevices in fast-flowing sectors. Habitat preferences also vary according to species. Water in the upper reaches of the Chapada Diamantina is cool and usually black (organic matter-stained), but copionodontines are recorded in a few clear-water streams, as well. Usually, they share their environment with few or no other fish species.

References

Trichomycteridae Pencil catfish of Brazil Endemic fish of Brazil Fish subfamilies Taxa named by Mário Cesar Cardoso de Pinna {{Trichomycteridae-stub