''Bryconops humeralis'' is a small freshwater fish distributed across northern

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 ...

. The name "humeralis" means "relating to the shoulder" (to the

humerus The humerus (; ) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a roun ...

), in reference to the distinct humeral patches that the fish sports. It is slightly longer than average in terms 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 specie ...

'', though still firmly within the standard range, and is slightly more slender than is usual for its congeners. Along with '' Bryconops vibex'', ''B. humeralis'' was described by

Barry Chernoff Barry may refer to: People and fictional characters * Barry (name), including lists of people with the given name, nickname or surname, as well as fictional characters with the given name * Dancing Barry, stage name of Barry Richards (born c. 1950 ...

Antonio Machado-Allison Antonio is a masculine given name of Etruscan origin deriving from the root name Antonius. It is a common name among Romance language-speaking populations as well as the Balkans and Lusophone Africa. It has been among the top 400 most popular male ...

in 1996 from the Orinoco River Basin in

Venezuela Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, República Bolivariana de Venezuela), is a country on the northern coast of South America, consisting of a continental landmass and many islands and islets in th ...

. It is known to be an

invertivore Feeding is the process by which organisms, typically animals, obtain food. Terminology often uses either the suffixes -vore, -vory, or -vorous from Latin ''vorare'', meaning "to devour", or -phage, -phagy, or -phagous from Greek φαγε ...

- that is, primarily consuming invertebrates (largely insects).

Description

''Bryconops humeralis'' reaches a maximum of roughly 8.6 cm (3.4 in) in

standard length Fish measurement is the measuring of individual fish and various parts of their anatomies. These data are used in many areas of ichthyology, including taxonomy and fisheries biology. Overall length * Standard length (SL) is the length of a fish m ...

, though averages closer to 7.5 cm (3.0 in). In comparison to other members of ''Bryconops'', it is close to the middle of the size range, if slightly above in larger specimens. Its body is on the shallow side, which can help differentiate it from several of its congeners. Its scales are largely silvery in color, its fins are dark-tinted but translucent, and the dorsal half of its caudal fin sports an orange or yellowish ocellus (eyespot). The specific epithet originates from the presence of a distinct humeral patch near each of ''B. humeralis's'' pectoral fins, which are its main distinguishing trait. This is a marking it shares with a few of its congeners, but other features can be used to tell them apart; for instance, '' B. inpai'' and ''B. munduruku'' have a pair of humeral marks by each fin as opposed to just one in ''B. humeralis''. ''B. vibex'' and '' B. marabaixo'' have single humeral patches (as opposed to paired), but other features distinguish them from ''B. humeralis'', such as number of scales beneath 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 ...

(''B. humeralis'' has fewer than ''B. vibex'') and body shape (''B. marabaixo'' has a deeper body than ''B. humeralis'', more reminiscent of ''B. inpai'').

Classification

''Bryconops humeralis'' has retained its designation as a member of ''Bryconops'' since its description in 1996. The genus ''Bryconops'' has two

subgenera 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 ...

, ''Bryconops'' and ''Creatochanes'', and ''B. humeralis'' is considered a member of ''Creatochanes'', which makes its full name ''Bryconops (Creatochanes) humeralis''. This sub-classification is based on the fact that it has at least one maxillary tooth on both sides of the mouth, which is the main characterizing facet of Creatochanes. ''Bryconops'' and its sister 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 ...

'' are considered members of the relatively recent 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 ...

, which was named in research by Oliveria et al. (2011). As a result, some resources (such as

ITIS The Integrated Taxonomic Information System (ITIS) is an American partnership of federal agencies designed to provide consistent and reliable information on the taxonomy of biological species. ITIS was originally formed in 1996 as an interagenc ...

and ADW) still list ''B. humeralis'' as a 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 ...

, which is where ''Bryconops'' was previously classified. Nonetheless, its modern placement is with the rest of ''Bryconops'' (under Iguanodectidae).

Distribution and ecology

Like other members of its genus, ''B. humeralis'' is found solely in northern

. It was first recognized from the

Orinoco Basin The Orinoco Basin is the part of South America drained by the Orinoco river and its tributaries. The Orinoco watershed covers an area of about 990000 km2, making it the third largest in South America, covering most of Venezuela and eastern p ...

, and its range has since been established as encompassing the Orinoco,

Negro In the English language, ''negro'' is a term historically used to denote persons considered to be of Black African heritage. The word ''negro'' means the color black in both Spanish and in Portuguese, where English took it from. The term can be ...

, and

Casiquiare The Casiquiare river () is a distributary of the upper Orinoco flowing southward into the Rio Negro, in Venezuela, South America. As such, it forms a unique natural canal between the Orinoco and Amazon river systems. It is the world's largest ...

rivers. Its affinity for blackwater habitats, such as the Rio Negro, indicates that it does not have high-oxygen needs; this is because blackwater habitats are low in oxygen, as microbes consume all available dissolved oxygen in the water. (Microbial decay is responsible for blackwater conditions; the breakdown of organic material releases trapped tannins into the environment.) Though extensive research has not been performed on ''B. humeralis's'' diet, it is known to prey on invertebrates. This is a similarity it shares with most other species of ''Bryconops'' (though some are documented herbivores). ''Bryconops humeralis'' 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 ...

References

{{Taxonbar, from=Q5619798 Fish described in 1996 Characiformes Fish of South America Fish of Venezuela