''Ancistrus formoso'' is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

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, ...

in the 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 ...

. It is native to

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 southe ...

, where it occurs only in the cave of Buraco do Ducho in the Formoso phreatic system in

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 ...

. It is a

stygobitic Stygofauna are any fauna that live in groundwater systems or aquifers, such as caves, fissures and vugs. Stygofauna and troglofauna are the two types of subterranean fauna (based on life-history). Both are associated with subterranean environments ...

species that is known to lack eyes and body pigmentation, which indicate a high level of specialization to living in a subterranean, lightless environment. It is one of three known stygobitic members of ''

Ancistrus ''Ancistrus'' is a genus of nocturnal freshwater fish in the family Loricariidae of order Siluriformes, native to freshwater habitats in South America and Panama. Fish of this genus are common in the aquarium trade where they are known as bushyn ...

'', alongside '' A. cryptophthalmus'' and '' A. galani''. The species reaches 7.9 cm (3.1 inches) SL.

References

formoso Formoso is a municipality in north Goiás state, Brazil. The population was 4,172 (2020) in a total area of 844 km². Highway connections from Goiânia are made by GO-080 / Nerópolis / São Francisco de Goiás / BR-153 / Jaraguá / GO-08 ...

Fish described in 1997 Fauna of Brazil Cave fish {{Hypostominae-stub