Copionodontinae
Encyclopedia
Copionodontinae is a subfamily of catfish
Catfish
Catfishes 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 heaviest and longest, the Mekong giant catfish from Southeast Asia and the second longest, the wels catfish of Eurasia, to detritivores...

es (order
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...

 Siluriformes) of the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Trichomycteridae
Trichomycteridae
Trichomycteridae is a family of catfishes commonly known as the pencil or parasitic catfishes. This family includes the infamous candiru fish, feared by some people for its alleged habit of entering into the urethra of humans....

. It includes two genera
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

, Copionodon
Copionodon
Copionodon is a genus of catfishes of the family Trichomycteridae. It includes three species, C. lianae, C. orthiocarinatus, and C. pecten. C. orthiocarinatus and C. pecten originate from the Mucujê River, a tributary of Paraguaçu River in Brazil. C...

and Glaphyropoma.

Classification

Copionodontines are remarkably primitive in body form, and lack many of the synapomorphies
Synapomorphy
In cladistics, a synapomorphy or synapomorphic character is a trait that is shared by two or more taxa and their most recent common ancestor, whose ancestor in turn does not possess the trait. A synapomorphy is thus an apomorphy visible in multiple taxa, where the trait in question originates in...

 that were previously used to diagnose the family Trichomycteridae. There is little doubt that the Copionodontinae forms a monophyletic
Monophyly
In common cladistic usage, a monophyletic group is a taxon which forms a clade, meaning that it contains all the descendants of the possibly hypothetical closest common ancestor of the members of the group. The term is synonymous with the uncommon term holophyly...

 group, diagnosed by several unambiguous synapomorphies, including a unique dentition
Dentition
Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, the characteristic arrangement, kind, and number of teeth in a given species at a given age...

 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
Chapada Diamantina is a region of Bahia state, in the Northeast of Brazil.The Chapada Diamantina has a dramatic landscape with high plains, table-top mesas, and steep cliffs or towers known as 'tepuy.' Before the arrival of the Portuguese in the 19th century, the only local inhabitants of the...

; though the plateau is drained by four river basins, so far, these fish are exclusively found in drainages associated with the Paraguaçu River
Paraguaçu River
The Paraguaçu River is a river in Bahia state of eastern Brazil. It originates in the Chapada Diamantina highlands of central Bahia following the chain of mountains called Sincura, and flows east 500 km to empty into the Baía de Todos os Santos....

.

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 (tea-stained), but there are records of copionodontines in a few clear water streams as well. Usually they share their environment with few or no other fish species.
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