Bryconops tocantinensis

Last updated

Bryconops tocantinensis
Bryconops tocantinensis female.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Characiformes
Family: Iguanodectidae
Genus: Bryconops
Species:
B. tocantinensis
Binomial name
Bryconops tocantinensis

Bryconops tocantinensis is a small freshwater fish from the rivers of Brazil. It has yellow-gold scales on its back and white scales on its belly, with a bright-silver stripe marking the divide between the two. It gets the name "tocantinensis" from its endemism to the upper Tocantins basin drainage - specifically, the Conceição River.

Contents

Description

Wild specimen Bryconops tocantinensis.jpg
Wild specimen

Bryconops tocantinensis reaches about 6.5 cm (2.6 in) in standard length (excluding the tail fin), [1] which makes it one of the smaller members of the genus. [2] The dorsal, adipose, and caudal fins are all entirely orange, which is a similarity it shares only with congeners B. humeralis and B. vibex . [3] However, it can easily be distinguished from the two because it lacks humeral spots (whereas the others have one on each side) and because it lacks teeth on the maxilla (vs. 1-3 on each side). [4]

The scales on the upper half of the body are a yellow-gold color, with a bright silver lateral stripe marking the divide; the lower half is white-to-silver. [4] The upper portion of the face and head is slightly darker, as are the distal portions of both lobes of the caudal fin. [3] It has 38 to 48 pored lateral line scales; these scales are easily visible, and can be used to distinguish B. tocantinensis from congeners B. vibex and B. rheoruber . [1] [5]

Sexual dimorphism

Bryconops tocantinensis demonstrates sexual dimorphism in that mature males sport bony hooks on the rays of the anal and pelvic fins. [4] (This is also seen in other members of Bryconops.) [6] Otherwise, they are very morphologically similar to one another, including in coloration (with the exception that larger females may have some orange near the pectoral fin). [3] This includes both in life and when preserved in alcohol.

Taxonomy

Wild shoal Bryconops tocantinensis wild.jpg
Wild shoal

Since its description in 2016, B. tocantinensis has been considered a member of the subgenus Bryconops due to the lack of teeth on its maxillaries. [3] There are nine other species classified as such alongside it. [5] The other subgenus in Bryconops, Creatochanes, is characterized by having 1 to 3 teeth on either side of the maxillary. [7]

Habitat and distribution

Bryconops tocantinensis is known only from the rio Conceição, a tributary of the rio Palma, which is a part of the upper rio Tocantins drainage. [3] The specific epithet "tocantinensis" is in reference to this. [8] (The suffix -ensis denotes being found in a specific location; compare Lynx canadensis, the Canada lynx, or Callopistria floridensis , the Florida fern moth.)

The Rio Conceição itself is a clearwater river with a depth of up to 1.5 m (5 ft). [4] The substrate is a mixture of sand and stones. [3] There is adequate riparian vegetation, largely in the form of trees and shrubs. [4]

Diet and ecology

Though few dietary specifics are known of B. tocantinensis, it is likely to be an insectivore or omnivore, as is common in the genus Bryconops. [6] [9] The presence of riparian vegetation in its natural habitat offers the possibility that it eats insects that fall into the water from trees overhead, as is seen in congeners B. inpai and B. magoi . [10] [11]

It is known to live peacefully with various other freshwater fish in its native range. Examples include Eigenmannia trilineata , Hoplerythrinus unitaeniatus , Astyanax goyacensis , species of Knodus (specifically Knodus breviceps ), and species of Ancistrus (bristlenose catfishes). [3] [4]

Conservation status

Bryconops tocantinensis has not been evaluated by the IUCN. [1] Nonetheless, the Tocantins basin at large is under anthropogenic threat, which may place it under greater survival pressure. The Rio Tocantins main already has many hydroelectric dams along its length, and more are planned for the future. [12] [13] Deforestation and logging are also among the current means of habitat destruction, which has a significantly negative impact on the riparian zone. [14]

Related Research Articles

<i>Bryconops</i> Genus of fishes

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 can be identified by way of a humeral patch, and others have a reddish ocellus, or eyespot, on one or both lobes of the dorsal fin.

<span class="mw-page-title-main">Iguanodectidae</span> Family of fish

Iguanodectidae is a family of freshwater fish in the order Characiformes that lives in South America. It is home to the subfamily Iguanodectinae and the monotypic Bryconops clade. Several species in the family, such as the green line lizard tetra, the tailspot tetra, and the orangefin tetra, are sometimes taken as aquarium fish.

<i>Bryconops alburnoides</i> Species of fish

Bryconops alburnoides is a small freshwater fish, approximately 6 inches long at its largest, that lives in the rivers of South America. It has a slender body, with a yellowish dorsal fin and yellow-tinged back scales that fade into silver on its belly. It is largely an insectivore that picks land-dwelling insects from the riverbanks, though it eats much more whenever rain washes prey into the water.

<i>Bryconops collettei</i> Species of fish

Bryconops collettei is a small freshwater fish from the rivers of South America. It is mostly silvery, with notable green iridescence on its sides, and a diffuse ocellus (eyespot) on the upper lobe of the caudal fin. Before its distinction as a separate species, specimens of B. collettei were misidentified as specimens of Bryconops caudomaculatus due to several morphological similarities, including a caudal ocellus and generally similar fin coloration.

<i>Bryconops cyrtogaster</i> Species of fish

Bryconops cyrtogaster is a midsize species of freshwater fish found in the Oyapock river in French Guiana and Brazil. It is overall silver, with an indistinct dark patch at the base of the tail fin that spreads onto the fin rays slightly. Originally described in 1926 under a different baisonym, it was the subject of a redescription in June 2020.

Bryconops disruptus is a small freshwater fish of the family Iguanodectidae. It is only found in the Rio Negro in South America. Like the rest of the genus Bryconops, B. disruptus is silvery in color, with a relatively deep chest and a notable set of teeth. The specific epithet "disruptus" refers to the incomplete lateral line.

Bryconops durbinae, sometimes listed under the name Bryconops durbini, is a small species of freshwater fish in the family Iguanodectidae. It is the smallest species of the genus Bryconops, and is endemic to the Tapajós river basin in Brazil.

Bryconops humeralis is a small freshwater fish distributed across northern South America. The name "humeralis" means "relating to the shoulder", in reference to the distinct humeral patches that the fish sports. It is slightly longer than average in terms of the genus Bryconops, though still firmly within the standard range, and is slightly more slender than is usual for its congeners.

Bryconops inpai is a small freshwater fish native to the rivers of South America. It only lives in two particular river systems - the Casiquiare and Negro - which means that its range is restricted to the northern half of the continent. It has indistinct humeral spots, and is bluish-silver in life, which is unusual for members of Bryconops; they are more often plain silver or greenish-silver.

<i>Bryconops magoi</i> Species of fish

Bryconops magoi is a small species of fish from South America. It is only found in Venezuela, 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.

Bryconops munduruku is a small freshwater fish of the family Iguanodectidae that lives in the rivers of South America. 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.

<i>Bryconops piracolina</i> Species of fish

Bryconops piracolina is a small fish that inhabits the waters of Brazil. 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.

Bryconops vibex is a small freshwater fish from the rivers of Venezuela, known solely from the Rio Cataniapo. The body is slender, though with an element of sturdiness, and it has one humeral spot by each pectoral fin. It bears visual similarities to several congeners, but can be differentiated by way of many factors.

Bryconops allisoni is a species of freshwater fish known from the rivers of Brazil. It is a recent addition to the genus (2019), currently considered a member incertae sedis. Its name honors Antonio Machado-Allison, an ichthyologist responsible for a great deal of work on the genus Bryconops.

Bryconops chernoffi is a species of freshwater fish that inhabits the rivers of Brazil. Specifically, it is found in the Rio Maicuru and Rio Ipixuna; the latter is a tributary of the former, which is a tributary of the Amazon river main. B. chernoffi demonstrates a preference for clear-water streams with sandy and rocky bottoms.

<i>Bryconops florenceae</i> Species of fish

Bryconops florenceae is a small freshwater fish that inhabits the rivers of South America. Comprehensive research is lacking due to B. florenceae being the most recently described of the genus, but researchers believe it to be a relatively widespread species. It is found throughout the Maroni, Mana, and Sinnamary river basins, which defines its range within Suriname and French Guiana.

Bryconops hexalepis is a small iguanodectid fish from the rivers of Brazil. It is solely found in the drainage of the Rio Tocantins. Rather elongate and quite slender, it is considered one of the smaller species of its genus, with tall scales and large eyes.

Bryconops marabaixo is a small freshwater fish from the lower Amazon basin, native to the Rio Jari. It is small and silvery, with a dark-gray back, and its fins are mostly clear, though the caudal fin has a dark stripe on the lower margin of the dorsal lobe, and a spot of red pigment just above that. Like many other members of Bryconops, it has a humeral spot, which is a mark near each pectoral fin.

Bryconops rheoruber is a species of freshwater fish from the rivers of Brazil. Its back scales are tan-to-cream, and its belly is silvery; the divide between the two colors is marked by a broad iridescent-silver stripe. Its fins are a mixture of pale, clear, and reddish, which contributed to its specific name. "Rheo" means "flow" or "current" in Greek, and "ruber" means "red" in Latin.

Bryconops sapezal is a small freshwater fish native to the Rio Tapajós basin of Brazil. It is one of the more recent additions to its genus, described in 2018, and has a name that means "covered in sapê", or thatching. This originates from the Sapezal municipality of Mato Grosso, Brazil, which is type locality of B. sapezal.

References

  1. 1 2 3 Froese, Rainer; Pauly, Daniel (eds.) (2022). "Bryconops tocantinensis" in FishBase . November 2022 version.
  2. Froese, Rainer and Pauly, Daniel, eds. (2022). Species of Bryconops in FishBase . November 2022 version.
  3. 1 2 3 4 5 6 7 Guedes, Tharles L. O.; Oliveira, Everton F.; Lucinda, Paulo H. F. (14 March 2016). "A new species of Bryconops (Ostariophysi: Characiformes: Characidae) from the upper rio Tocantins drainage, Brazil". Neotropical Ichthyology. 14 (2). doi: 10.1590/1982-0224-20150176 . Retrieved 8 November 2022.
  4. 1 2 3 4 5 6 "Bryconops tocantinensis, Guedes, Oliveira, & Lucinda, 2016". Plazi TreatmentBank. Plazi. Retrieved 8 November 2022.
  5. 1 2 Silva-Oliveira, Cárlison; Sabaj, Mark Henry; Ota, Rafaela Priscila; Py-Daniel, Lúcia H. Rapp (6 June 2019). "Bryconops rheorubrum (Characiformes: Iguanodectidae), new species from the Rio Xingu Rapids, Brazil". Proceedings of the Academy of Natural Sciences of Philadelphia. 166 (1): 1–21. doi:10.1635/053.166.0115. S2CID   210640024 . Retrieved 8 November 2022.
  6. 1 2 "THE FISH FAMILIES". Field Guide to the Fishes of the Amazon, Orinoco, and Guianas, edited by Peter van der Sleen and James S. Albert, Princeton: Princeton University Press, 2017, pp. 95-96. https://doi.org/10.1515/9781400888801-009
  7. Chernoff, Barry; Machado-Allison, Antonio (31 December 2005). "Bryconops". doi:10.5281/zenodo.6265593.{{cite journal}}: Cite journal requires |journal= (help)
  8. Scharpf, Christopher; Lazara, Kenneth J. (15 September 2020). "Order CHARACIFORMES: Families IGUANODECTIDAE, TRIPORTHEIDAE, BRYCONIDAE, CHALCEIDAE and GASTEROPELECIDAE". The ETYFish Project. Retrieved 7 November 2022.
  9. Echevarría, Gabriela; González, Nirson (November 2018). "Fish taxonomic and functional diversity in mesohabitats of the River Kakada, Caura National Park, Venezuela". Nature Conservation Research. 3 (Suppl. 2). doi: 10.24189/ncr.2018.048 . Retrieved 6 November 2022.
  10. Froese, Rainer; Pauly, Daniel (eds.) (2022). "Bryconops inpai" in FishBase . November 2022 version.
  11. Froese, Rainer; Pauly, Daniel (eds.) (2022). "Bryconops magoi" in FishBase . November 2022 version.
  12. Millikan, Brent. "Araguaia & Tocantins Rivers". International Rivers Archive. International Rivers. Retrieved 8 November 2022.
  13. Switkes, Glenn. "Araguaia and Tocantins rivers, Brazil". International Rivers Network. Retrieved 8 November 2022.
  14. Sen Nag, Oishimaya (25 April 2017). "The Tocantins River". worldatlas.com. WorldAtlas. Retrieved 8 November 2022.