''Bryconops piracolina'' is a small fish that inhabits the waters of

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 ...

. It is slender and silvery in color, like many fish in ''Bryconops'', but can be distinguished from other members by way of its dorsal fin, which has a black patch of color extending up from the fin-base; congeners usually have light pigment in the dorsal fin, or a brighter color (as in the orangefin tetra, ''B. affinis''). Its specific epithet, ''piracolina'', is in reference to the stream where it was found, the Igarapé Piracolina (which is located in the Río Madeira basin).

Description

''Bryconops piracolina'' reaches a maximum of roughly 7.1cm (2.8 in) in

standard length Fish measurement is the measuring of individual fish and various parts of fish anatomy, their anatomies, for data used in many areas of ichthyology, including Taxonomy (biology), taxonomy and fishery biology. Overall length Standard length (SL) is ...

(excluding the tail fin). This places it slightly to the smaller side of 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 species ...

'' as a whole. Its dorsal fin sports pigmentation along the base that streaks away from the body, which is a unique feature that can be used to distinguish it from its congeners. It lacks humeral spots, which is another distinguishing feature, and its adipose fin is entirely black. The lattermost aspect is shared with '' Bryconops inpai'' and '' Bryconops munduruku'', but these two are dissimilar to ''B. piracolina'' in many ways. Its slender body shape and general silver coloration are otherwise common aspects. When a specimen is preserved in alcohol, the scattered black

chromatophores Chromatophores are cells that produce color, of which many types are Biological pigment, pigment-containing cells, or groups of cells, found in a wide range of animals including amphibians, fish, reptiles, crustaceans and cephalopods. Mammals an ...

(pigment cells) on its face, head, and upper jaw become more evident, though they have little impact on overall coloration. Its

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 epithelia ...

also becomes much clearer, manifesting as a bold, dark stripe against scales that turn a yellowish-brown. The lateral line scales themselves are pored only to the end of the hypural plate, the plate that joins the fish's tail to its body.

Taxonomy

''Bryconops piracolina'', upon being named in 2011, was assigned to the

subgenus In biology, a subgenus ( 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 the ge ...

''Bryconops''. It has fewer teeth than is necessary on the

maxilla In vertebrates, the maxilla (: maxillae ) is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The two maxil ...

(one to three teeth on both sides) for assignment to the other subgenus, ''Creatochanes''. As with the rest of ''Bryconops'', it was once considered a member of the family

Characidae Characidae, the characids, is a family of freshwater subtropical and tropical fish belonging to the order Characiformes. They are found throughout much of Central and South America, including such major waterways as the Amazon and Orinoco Riv ...

, but research in 2011 moved ''Bryconops'' to the family

Iguanodectidae Iguanodectidae is a family of freshwater fish in the order Characiformes that lives in South America. It contains three genera: ''Iguanodectes, Piabucus'', and ''Bryconops''. Several species in the family, such as the green line lizard tetra (' ...

, alongside the genera '' Iguanodectes'' and ''

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 maxi ...

''. ''Bryconops piracolina'' has no known scientific synonyms, having retained its original name.Bryconops piracolina Wingert & Malabarba, 2011
in GBIF Secretariat (2021). GBIF Backbone Taxonomy. Checklist dataset https://doi.org/10.15468/39omei accessed via GBIF.org on 2022-11-06. It also has no widely-accepted common names, though "Piracolina tetra" has been suggested as a result of its type locality. (The specific epithet "piracolina" originates from the Igarapé Piracolina, where B. piracolina was first described.) Members of Bryconops are but a handful of fish often referred to as "

tetras Tetra is the common name of many small freshwater characiform fishes. Tetras come from Africa, Central America, and South America, belonging to the biological families Characidae, Alestidae (the "African tetras"), Lepidarchidae, Lebiasi ...

"; examples include ''B. affinis'' (the orangefin tetra), ''B. caudomaculatus'' (the tailspot tetra), and ''B. melanurus'' (the tail-light tetra).

Distribution and ecology

As is reflected in the specific epithet, ''B. piracolina'' was first cited from the Igarapé Piracolina (or Piracolina Creek in English), a small stream that flows into the Rio Machado located in

Vilhena Vilhena () is the easternmost municipality in the Brazilian state of Rondônia. Its population was 102,211 (IBGE-2020) and its area is 11,519 km2. – IBGE It is the fifth-largest city in Rondônia and has the best HDI in the state (0,771 ...

Rondônia Rondônia () is one of the 26 states of Brazil, located in the northern subdivision of the country (central-western part). It is bordered by Acre (state), Acre in the west, Amazonas, Brazil, Amazonas in the north, Mato Grosso in the east, and Bo ...

. In turn, the Río Machado is a tributary of the Río Madeira. There is evidence to suggest that ''B. piracolina'' is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to the area, along with several other species therein. Endemism is a trait known from tributaries of the Río Machado, though in a somewhat limited capacity. The Igarapé Piracolina itself is a clear-water creek with a fast current and sandy substrate. Its width ranges from 1-3 m (about 3-10 ft), and depth from 0.3-1.5 m (1-5 ft). The Piracolina and its tributaries are surrounded by cultivated farmland, largely

soy The soybean, soy bean, or soya bean (''Glycine max'') is a species of legume native to East Asia, widely grown for its edible bean. Soy is a staple crop, the world's most grown legume, and an important animal feed. Soy is a key source of f ...

and

corn Maize (; ''Zea mays''), also known as corn in North American English, is a tall stout Poaceae, grass that produces cereal grain. It was domesticated by indigenous peoples of Mexico, indigenous peoples in southern Mexico about 9,000 years ago ...

, with very little

riparian A riparian zone or riparian area is the interface between land and a river or stream. In some regions, the terms riparian woodland, riparian forest, riparian buffer zone, riparian corridor, and riparian strip are used to characterize a ripar ...

vegetation.

Conservation status

Though little is known of population trends and environmental threats, ''B. piracolina'' is considered a species of

least concern A least-concern species is a species that has been evaluated and categorized by the International Union for Conservation of Nature (IUCN) as not being a focus of wildlife conservation because the specific species is still plentiful in the wil ...

by the IUCN.

References

{{Taxonbar, from=Q5634031 Taxa named by Luiz Roberto Malabarba Fish described in 2011 Bryconops Freshwater fish of Brazil Endemic fish of Brazil