''Bryconops magoi'' is a small species of fish from

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

. It is only found in

Venezuela Venezuela, officially the Bolivarian Republic of Venezuela, is a country on the northern coast of South America, consisting of a continental landmass and many Federal Dependencies of Venezuela, islands and islets in the Caribbean Sea. It com ...

, along with sister species '' Bryconops collettei''. Its tail-fin markings help to differentiate it from various congeners, as does its fairly restricted range. It is most closely related to ''B. collettei'' and '' Bryconops caudomaculatus'', and it was once considered synonymous with the latter; specimens of ''B. magoi'' and ''B. collettei'' both were routinely misidentified as ''B. caudomaculatus'' before being given species distinction.

Description

''B. magoi'' has a maximum size within the range of 7.0 cm (2.8 in), which places it 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 caudal fin (tail fin) bears a rather diffuse

ocellus A simple eye or ocellus (sometimes called a pigment pit) is a form of eye or an optical arrangement which has a single lens without the sort of elaborate retina that occurs in most vertebrates. These eyes are called "simple" to distinguish the ...

(eyespot), the upper half of which is colored red; this is a similarity it shares with B. collettei. This eyespot is not well-defined, but is clear against the dark coloration of the caudal fin overall (which is dense in

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

). Its scales are overall metallic or gray towards the back, becoming more silvery towards the belly, and it has a

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 ...

stripe in three colors; the base is a black band with a silver stripe beneath, finished with an iridescent-yellow line. '' Bryconops caudomaculatus'' and '' Bryconops collettei'' both bear multiple similarities to ''Bryconops magoi'', but there are various ways to tell them apart. One of these is the pored

scales, which stop at the hypural plate and do not extend onto the caudal fin itself in ''B. caudomaculatus''; In ''B. magoi'', they extend two to three scales beyond that point. (This is a diagnostic aspect that ''B. magoi'' shares with ''B. collettei''.) ''B. magoi'' and ''B. collettei'' are similar in many ways as well, such as coloration (though more green in ''B. collettei''), but their varying body shapes make them dissimilar enough to tell apart. Such aspects include a longer snout (a mean of 6.8% of the body length in ''magoi'' vs. 4.7% in ''collettei'') and a shorter spine (modally 41-42 vertebrae in ''magoi'' vs. 42-43 in ''collettei'').

Taxonomy

''Bryconops magoi'', along with congener ''Bryconops collettei'', was first described in a study in 2005. Said study also contained a redescription of ''Bryconops caudomaculatus'', due to the species' generally enigmatic nature. Its full scientific name is ''Bryconops (Bryconops) magoi'', as it is a part of 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'' (as opposed to the other subgenus in ''Bryconops'', ''Creatochanes''). It is considered a part of the ''Bryconops caudomaculatus''

species complex In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each oth ...

because of morphological similarities and a history of synonymy therein. ''Bryconops magoi'', as with the rest of ''Bryconops'', was once considered a characin, or 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 ...

. However, research in 2011 by Oliveira et al. moved the genera ''Bryconops'', ''

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 ...

'', and '' Iguanodectes'' into 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 (' ...

, which is where ''B. magoi'' currently stands. (Within Iguanodectidae, ''

'' is its own monotypic clade, whereas ''Piabucus'' and ''Iguanodectes'' make up the subfamily Iguanodectinae). ''Bryconops'' is still listed as a member of Characidae by some sources, such as

Animal Diversity Web The Animal Diversity Web (ADW) is a non-profit group that hosts an online database site that collects natural history, classification, species characteristics, conservation biology, and distribution information on species of animals. The website ...

. The specific epithet "magoi" pays homage to Francisco Mago-Leccia, who is referred to in the nominal study as the “pioneer of modern ichthyological studies in Venezuela”. There are no common names currently accepted for ''B. magoi'', though "Mago's tetra" has been suggested as an extension of the species's namesake.

Habitat and ecology

''Bryconops magoi'' is found only in

, with a fairly restricted range. All paratypes were collected from the type locality: the Rio Moquete at Paso Bajito, which is located in the Francisco de Miranda Municipality, in the Venezuelan state of

Anzoátegui Anzoátegui State (, ) is one of the 23 states of Venezuela, states of Venezuela, located in the northeastern region of the country. Anzoátegui is well known for its beaches that attract many visitors. Its coast consists of a single beach approx ...

. This is just north of the

Orinoco river The Orinoco () is one of the longest rivers in South America at . Its drainage basin, sometimes known as the Orinoquia, covers approximately 1 million km2, with 65% of it in Venezuela and 35% in Colombia. It is the List of rivers by discharge, f ...

, the largest river in Venezuela. It demonstrates a preference for fast-moving water over sandy substrate, and is most often found swimming close to the surface, schooling with other species of fish. It is not often taken from the wild for the aquarium trade, and is not considered at risk of population depletion therein. It has not been evaluated by the

IUCN The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the status ...

. In demonstrating a preference for a blackwater habitat (many rivers in the Orinoco basin are blackwater), B. magoi also demonstrates that it does not have high-oxygen needs. Microbial activity is responsible for blackwater conditions, and microbes consume a large percentage of available dissolved oxygen in the process of decay (and said decay releases dark-colored

tannins Tannins (or tannoids) are a class of astringent, polyphenolic biomolecules that bind to and precipitate proteins and various other organic compounds including amino acids and alkaloids. The term ''tannin'' is widely applied to any large po ...

into the environment). Thus, fish with high-oxygen needs are not suited to blackwater environments, which are low-oxygen by way of the processes that characterize them.

Diet

Cursory examination shows that ''B. magoi'' feeds at the surface of the water, largely targeting insects that fall in from trees hanging above. This is a similarity it shares with congener '' B. inpai'', which also has a taste for terrestrial insects and other invertebrates that originate outside of the river system. The rest of ''Bryconops'' is also largely composed of invertivores, though some are noted herbivores.

References

{{Taxonbar, from=Q6417142 Taxa named by Barry Chernoff Taxa named by Antonio Machado-Allison Fish described in 2005 Bryconops Freshwater fish of Venezuela Endemic fauna of Venezuela