''Bryconops munduruku'' is a small freshwater fish of the family

Iguanodectidae Iguanodectidae is a family of freshwater fish in the order Characiformes that lives in South America. It is home to the subfamily Iguanodectinae (Eigenmann, 1909) and the monotypic ''Bryconops'' clade. Several species in the family, such as the ...

that lives in the rivers of

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 ...

. Its adipose fin is black, with a clear base, and it has two humeral spots, which is a feature it shares with few congeners. Its fins are a variety of yellow, red, black, and clear, and mature males have hooks on select fin-rays. Originally cited from the lower

Rio Tapajós Rio or Río is the Portuguese, Spanish, Italian, and Maltese word for "river". When spoken on its own, the word often means Rio de Janeiro, a major city in Brazil. Rio or Río may also refer to: Geography Brazil * Rio de Janeiro * Rio do Sul, a ...

, ''B. munduruku's'' name pays homage to its type locality. Known as the Tapajós-Tapera, a denomination of Munduruku Indians (an indigenous culture of Brazil) formed the settlement that became the municipality from whence ''B. munduruku'' was described, Aveiro.

Taxonomy

''Bryconops munduruku'' is considered a member of the

subgenus In biology, a subgenus (plural: subgenera) is a taxonomic rank directly below genus. In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between t ...

''Creatochanes'' in the genus ''

Bryconops ''Bryconops'' is a genus of freshwater fish in the family Iguanodectidae from South America. It consists of small fish, all under half-a-foot long, with slender bodies and silvery scales, though there is some mild color variation. Several specie ...

''. It has been regarded as such since its description in 2015. It is sometimes listed as a characin, or member of the family

Characidae Characidae, the characids or characins is a family of freshwater subtropical and tropical fish, belonging to the order Characiformes. The name "characins" is the historical one, but scientists today tend to prefer "characids" to reflect their st ...

, but a study in 2011 moved the genera ''

'', ''

Piabucus ''Piabucus'' is a genus of freshwater tetras in the family Iguanodectidae. All three species are found in South America, largely the Amazon and its major tributaries. None of them are longer than half a foot long, with the largest reaching a max ...

'', and ''

Iguanodectes ''Iguanodectes'' is a genus of freshwater fish found in tropical South America, with eight currently described species. They are all small tetras, none longer than 5 inches, and often have attractive silvery or striped scales, which makes them a t ...

'' into a new family,

. ''Bryconops munduruku'' has retained its original name, and has no known synonyms.

Etymology

The specific epithet of ''Bryconops munduruku'' is in reference to its type locality. A group of Munduruku Indians, the Tapajós-Tapera, settled in the place that would eventually become Aveiro, which is the municipality where ''B. mundukuru'' was discovered. The genus name "Bryconops" means "resembling ''

Brycon ''Brycon'' is a genus of fish in the family Characidae found in freshwater habitats in Central and South America, ranging from southern Mexico to northern Argentina. Despite not being closely related to true trout, they are sometimes called South ...

''" ("ops" means "appearance").

Description

''Bryconops munduruku'' is a reddish color above the

lateral line The lateral line, also called the lateral line organ (LLO), is a system of sensory organs found in fish, used to detect movement, vibration, and pressure gradients in the surrounding water. The sensory ability is achieved via modified epithelial ...

, with a light-gray belly. It reaches a length of about 9.6 cm (3.8) at a maximum. The upper regions of the head, jaw, and face are a dark gray color. The eyes are red at the upper margin, and yellow everywhere else. The dorsal fin has a red base half and a hyaline (clear) outer half, which is a pattern shared by the caudal fin. The pectoral and pelvic fins, as well as the first few rays of the anal fin, are yellow. It has two humeral spots, which is a similarity it shares with congener ''B. inpai'', but ''B. inpai'' has a stripe extending from its anal-fin base to its caudal-fin base whereas ''B. munduruku'' has a uniform color pattern therein. The

adipose fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as s ...

is black with a clear base, which differentiates ''B. munduruku'' from ''B. inpai'' and '' B. piracolina'', both of which have entirely black adipose fins.'''' ''B. piracolina'' can also be told from ''B. munduruku'' because its dorsal fin sports a large black blotch.

Sexual dimorphism

''Bryconops munduruku'' demonstrates

sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...

. In mature males, several rays of the anal, pelvic, and dorsal fins bear hooks or spines that are absent in females. The hooks on the anal fin are larger, while the ones on the dorsal and pelvic fins are more akin to spines. This is a feature not uncommon in ''Bryconops'', also demonstrated by congeners like '' B. florenceae'', '' B. cyrtogaster'', and '' B. gracilis''.

Habitat and ecology

''Bryconops munduruku'' was originally described from a small tributary of the

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 ...

, the igarapé Açu; this is a location about 10 kilometers from Aveiro, in Brazil's

Pará State Pará is a state of Brazil, located in northern Brazil and traversed by the lower Amazon River. It borders the Brazilian states of Amapá, Maranhão, Tocantins, Mato Grosso, Amazonas and Roraima. To the northwest are the borders of Guyana and Sur ...

. Congeners that also live in the Rio Tapajós are '' B. durbinae'', '' B. gracilis'', and '' B. melanurus''. There is evidence to suggest that ''B. munduruku'' is an endemic species therein. With a pH that ranges from 4.5 to 7.8, the Tapajós is a rather acidic clearwater river. ''B. munduruku'' in particular was collected from fast-moving water over a sandy riverbed, a specific environment it shares with congener '' B. giacopinii''. Part of the igarapé Açu is within the

Tapajós National Forest The Tapajós National Forest ( pt, Floresta Nacional do Tapajós) is a Brazilian national forest in the state of Pará, Brazil. It supports sustainable exploitation of the natural resources in an area of Amazon rainforest. Location The Tapajós ...

and is therefore bordered by dense vegetation; this may present a source of food for ''B. munduruku'', though specific dietary needs are not known. (Members of ''Bryconops'' tend to either be insectivores that take supplemental plant material or sole herbivores.) ''Bryconops munduruku'' can be found in

sympatry In biology, two related species or populations are considered sympatric when they exist in the same geographic area and thus frequently encounter one another. An initially interbreeding population that splits into two or more distinct species sh ...

with ''B. giacopinii'', '' Hyphessobrycon agulha'', ''Moenkhausia comma'', and various species of ''

Hemigrammus ''Hemigrammus'' is a genus of freshwater fish in the family Characidae native to South America (including Trinidad) and commonly seen in the aquarium trade. These are medium-small tetras where the largest species reach up to around . Species Th ...

''.

Conservation status

''Bryconops munduruku'' has not been evaluated by the

IUCN The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

. Nonetheless, its native habitat of the Rio Tapajós is under constant anthropogenic threat, especially in the modern era. Usually, the water is clear, but instances of illegal gold mining have kicked up or added so much sediment that portions of the river turn entirely brown. Illegal gold mining is a thriving industry in South America, despite its dangers to both participants and to the environment, and so species like ''B. munduruku'' are under greater survival pressure. The importance of the Rio Tapajós, however, has prompted various plans for infrastructure development and legal mining operations to be reconsidered, which offers ''B. munduruku'' a greater chance of survival. This is also positive news for a human population of roughly 1.4 million people.

References

{{Taxonbar, from=Q46323176 Fish described in 2015 Characiformes Fish of South America Fish of Brazil