Astyanax caucanus

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Astyanax caucanus
Astyanax caucanus (16177106643).jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Characiformes
Family: Characidae
Genus: Astyanax
Species:
A. caucanus
Binomial name
Astyanax caucanus
Steindachner, 1879

Astyanax caucanus is a small species of freshwater fish only found in Colombia. While little research exists regarding its ecological habits, such as diet and mating practices, its environment preferences are known to include marshy lowlands, and it easily lives in sympatry with various other fish species in the Cauca and Magdalena river basins. It is not known to share a habitat with any other species of Astyanax, but has a noted phyletic relationship to a group of congeners including Astyanax filiferus, Astyanax stilbe, and Astyanax magdalenae.

Congener Astyanax atratoensis has been noted to bear a strong visual resemblance to A. caucanus, and researchers as early as 1908 were commenting on a possible relationship. It is unknown if this remains the case, as A. atratoensis and A. caucanus no longer share a subgenus; A. caucanus has been considered a member of subgenus Zygogaster since its description, and A. atratoensis has been moved from Zygogaster to Poecilurichthys by recent research.

Taxonomy

When originally described by Austrian ichthyologist Franz Steindachner in 1879, A. caucanus was assigned the name Tetragonopterus caucanus. [2] Otherwise, it lacks any synonyms. [3]

There are three subgenera in Astyanax - Astyanax, Poecilurichthys, and Zygogaster [4] - and A. caucanus has been placed in Zygogaster, making its full name Astyanax (Zygogaster) caucanus. Four other species originally shared this subgenus: Astyanax stilbe , Astyanax atratoensis , Astyanax magdalenae , and Astyanax filiferus . [5] In 1908, German-American ichthyologist Carl H. Eigenmann remarked that A. atratoensis may be one of the more closely related species to A. caucanus. [6] Based on modern understandings, this may not remain the case; recent research places A. atratoensis in the subgenus Poecilurichthys. [7] [8] (The others remain in Zygogaster.) In 1917, Eigenmann also remarked upon the close relationship between A. caucanus and A. stilbe. [9]

Etymology

The genus name "Astyanax" is an allusion to the Iliad, a Greek epic poem in which Astyanax was the son of Trojan prince Hector. The reasoning behind this was not made clear in the nominal text, but modern etymologists suspect that the appearance of type species Astyanax argentatus may be responsible; its scales are large and silvery, perhaps comparable to armor or a shield. The subgenus name "Zygogaster" originates in Greek, wherein "zygos" means pair or balanced, and "gaster" means belly, referring to the symmetrical scales on either side of the ventral midline. The specific epithet "caucanus" refers to the Río Cauca, Colombia, which is the type locality of the species. [10]

Astyanax caucanus lacks a common name. [11] "Cauca tetra" has been suggested based on the type locality and specific name.

Description

Collected specimens of A. caucanus range from 3.6 to 17.0 cm (1.4–6.7 in) standard length (SL, without the tail fin). There are 11 rays in the dorsal fin, 36–41 rays in the anal fin (most often 38), and 36–42 scales in the lateral line (most often 38). [9] There are 7 or 8 scale rows both above and below the lateral line. When compared with congeners A. filiferus and A. magdalenae from the same subgenus, A. caucanus presents with a somewhat more generalized morphology, while the other two are more specialized for their environments. [5] Sexual dimorphism is unknown.

Astyanax caucanus bears a strong resemblance to congener Astyanax atratoensis, and the shared features include coloration. A. caucanus is an iridescent silver with a slightly darker back and a lateral stripe in a lighter silver; this lateral stripe starts at a vertically elongate humeral spot and ends at a blotch of pigment on the caudal peduncle. [6] When preserved in alcohol, the scales are largely light-brown and the fins are paler than the body. The lateral stripe remains silvery, and the eye turns a silvery brown. [12]

Distribution and ecology

Astyanax caucanus was originally described from the Cauca River Basin in Colombia, [13] and is solely recorded from the country (located in the far northwest of South America). [14] Since discovery, additional populations have been documented in the Magdalena River Basin, another basin in Colombia. [15] [16] It appears not to live in regions above 900 meters (approx. 3000 feet) in elevation, making it a lowland species. [9]

Astyanax caucanus has been noted to inhabit swampy areas. [17] In aquatic macrophyte patches (multicellular plants, as opposed to algae) of the Ayapel Swamp Complex in Colombia, A. caucanus is one of a small handful of species that makes up a great deal of the biomass; other common species with which it coexists in the same region include Eigenmannia virescens , Roeboides dayi , Cyphocharax magdalenae , Triportheus magdalenae , Caquetaia kraussii , and Aequidens latifrons . [18]

Details regarding other ecological aspects, such mating practices, dietary needs, and behavior, are sparse.

Conservation status

The IUCN considers A. caucanus a species of least concern due to a wide range and a lack of active threats. [1] Because A. caucanus is an abundant and hardy species, it is unlikely that any factors will have a severe negative impact on population levels. [18] Its native range, however, may be facing ongoing environmental pressures.

A 2007 article from Colombian newspaper El Tiempo regarding the Cauca suggests pollution rates as high as 500 tons of residual waste per day. Mines for sand, bauxite, gold, and coal all contribute to this, as well as cities along the river's length, though not as much as industrial pollutants. [19] To counter this and other factors, the upper Cauca is the subject of an ongoing restoration effort. [20]

The Magdalena is also subject to various negative factors, including climate change, invasive species, deforestation, and water pollution, all of which were described in detail as part of one 2022 study performed to reassess the river's importance to the region, and therefore to reassess how high it should be prioritized as a conservation project. [21] Conservation of the Magdalena would not only benefit aquatic species like A. caucanus, but would also benefit the 80% of Colombia's population that lives in the basin. [22]

Related Research Articles

<span class="mw-page-title-main">Magdalena River</span> River in Colombia

The Magdalena River is the main river of Colombia, flowing northward about 1,528 kilometres (949 mi) through the western half of the country. It takes its name from the biblical figure Mary Magdalene. It is navigable through much of its lower reaches, in spite of the shifting sand bars at the mouth of its delta, as far as Honda, at the downstream base of its rapids. It flows through the Magdalena River Valley.

<i>Astyanax</i> (fish) Genus of fishes

Astyanax is a genus of freshwater fish in the family Characidae of the order Characiformes. Some of these fish, like many of their relatives, are kept as aquarium pets and known collectively as tetras. With around 150 described species and new ones being described yearly, this genus is among the largest of the entire order; Hyphessobrycon also has more than 145 species and which one is larger at any one time depends on whether more species have been recently described in one or the other. The blind and colorless cave tetra of Mexico is a famous member of the genus, but its taxonomic position is disputed: Some recognize it as part of the Mexican tetra and this is supported by phylogenetic evidence, but others recognize the cave form as a separate species, A. jordani.

<i>Hemibrycon</i> Genus of fishes

Hemibrycon is a genus of characins. They are mainly found in South America, Trinidad in the Caribbean), and H. dariensis of east Panama.

<i>Carlastyanax</i> Genus of fishes

Carlastyanax aurocaudatus is a small species of freshwater fish in the family Characidae native to the Río Cauca in Colombia. It is the only member of the monotypic genus Carlastyanax, which was named in 1972 specifically for the species by Jacques Géry. Upon description, it was named Astyanax aurocaudatus by Carl H. Eigenmann. There has been debate concerning whether or not the genus should be recognized, but C. aurocaudatus is currently considered a valid species.

<i>Astyanax argentatus</i> Species of fish

Astyanax argentatus is a small freshwater fish native to northern Central America and southern North America. Given its native range, it is also known as the Texan tetra. Little has been published regarding the feeding habits or behavior of A. argentatus, but it is known to have the northernmost distribution of any member of the genus Astyanax.

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

Bryconops gracilis is a small species of freshwater fish from the rivers of South America. It is one of multiple species for which the common name "lambari" is used. Though not well-studied, it has been re-described in recent years in order to differentiate it from Bryconops alburnoides, a congener to which it bears a strong resemblance.

Farlowella yarigui is a species of catfish in the family Loricariidae. It is native to South America, where it occurs in the Topón River, which is part of the middle Magdalena River basin in Colombia. It is only found in the vicinity of partially submerged vegetation and pieces of wood, with the species being absent in other microhabitats within the main channel of the Topón. It is known to occur alongside the species Astyanax caucanus, Astyanax magdalenae, Astyanax filiferus, Lasiancistrus caucanus, and Roeboides dayi, as well as members of the genera Chaetostoma, Creagrutus, Hemibrycon, and Sturisoma. The species reaches 11.2 cm in standard length and is believed to be a facultative air-breather.

<i>Astyanax angustifrons</i> Species of fish

Astyanax angustifrons, sometimes referred to as the Campeche tetra, is a small freshwater fish from the rivers of Central and South America. It has a healthy distribution across southern Mexico and northern Guatemala, and is relatively common within its native range. Details regarding its diet and behavior are sparse, but it lives in areas with plentiful riparian vegetation, and most other members of the genus are omnivorous. Its habitat includes places affected by pollution and human activity; nonetheless, it is not endangered.

<i>Astyanax aramburui</i> Species of fish

Astyanax aramburui is a small freshwater fish from the rivers of South America, restricted to a relatively small region within the Paraná and Uruguay river basins of Argentina. It was named after the scientist who established a professional presence for ichthyology in the country, Raúl Arámburu. Considered a near-threatened species by the IUCN, its range includes creeks in a sub-basin affected by various forms of pollution.

<i>Astyanax argyrimarginatus</i> Species of fish

Astyanax argyrimarginatus is a small species of freshwater fish native to various river basins in Brazil. Originally thought to be restricted to the Tocantins-Araguaia river system, a study in 2012 expanded its range to include the Rio Xingu, as well. Specific biotope preferences are unknown, but it is mostly collected from clearwater streams in fairly good health. Its relative abundance and presence in some protected locales means that it is not endangered.

<i>Astyanax asuncionensis</i> Species of fish

Astyanax asuncionensis is a small species of freshwater fish described in 1972 from Asunción, the capital of Paraguay in South America. Its specific epithet is in reference to this. Currently, its range is known to encompass areas of not just Paraguay but also Argentina and Brazil. It is an adaptable, omnivorous species that easily lives in sympatry with various congeners.

<i>Astyanax atratoensis</i> Species of fish

Astyanax atratoensis is a small freshwater fish that occupies the Atrato river basin in Colombia. Originally described from a tributary therein, the Truandó River, it gets its specific epithet from the region. Though it faces no imminent threats, A. atratoensis inhabits waterways with a history of severe environmental pressure in the form of anthropogenic pollution. Several restoration efforts have been undertaken in the relevant regions.

<i>Astyanax belizianus</i> Species of fish

Astyanax belizianus is a small freshwater fish native to various regions of Central America. Little is known of its diet or specific environmental preferences, but it was first recorded in Belize. Modern ichthyology has expanded its range into Guatemala and Honduras, where it inhabits various rivers and lake tributaries. It is a silvery fish that may have a slight yellowish tint to its scales. The body is deep, especially in comparison to similar species from the same genus.

<i>Astyanax bimaculatus</i> Species of fish

The twospot astyanax, also called the two-spot tetra, is a small species of freshwater fish native to South America. It is a middlingly common tetra in the aquarium industry, with hobbyist reports of its sale and presence, and it is also a well-studied member of the genus Astyanax in wild settings. Amateur aquarists report peaceful schooling behavior in captivity, though fish in wild schools may turn on one another if presented with the threat of a predatory species.

<i>Astyanax boliviensis</i> Species of fish

Astyanax boliviensis is a small species of fish native to a handful of rivers in northern Bolivia. Its scientific name is an allusion to its range, which includes the Candelaria, Madidi, and Mamoré rivers. Though it lacks a conservation status from the IUCN, a significant portion of its habitat is contained within the Madidi National Park, one of the largest protected regions in the world.

<i>Astyanax bourgeti</i> Species of fish

Astyanax bourgeti is a small species of freshwater fish native to the upper Amazon river in Brazil. Originally described in 1908, it is not a particularly well-studied member of the genus Astyanax, but there is enough information available to establish a native range, an appearance, and potential relationships to congeners; for example, A. bourgeti is a known member of the subgenus Poecilurichthys, and has been considered such for most of its existence. Biotope preferences, sympatry, diet, and behavior are all unknown.

<i>Astyanax brachypterygium</i> Species of fish

Astyanax brachypterygium is a small species of freshwater fish endemic to a collection of high-elevation streams in Brazil. It was named in 2001 alongside congener Astyanax cremnobates, to which it bears a strong resemblance; physical details help to differentiate between the two. Its scales are a greenish-brown on the back and silver on the belly, with reddish fins and a dark humeral spot. One of its defining features is a notably short anal-fin base, which has 13 to 15 rays.

<i>Astyanax brevirhinus</i> Species of fish

Astyanax brevirhinus is a small species of freshwater fish known only from a river basin in northeastern Brazil. It is somewhat understudied and lacks a conservation status, but it is present in a region that is the subject of an ecological restoration project - the Jequitinhonha River. Specifics of diet and behavior are unknown, though shoaling activity has been observed in laboratory conditions.

<i>Deuterodon sazimai</i> Species of fish

Deuterodon sazimai is a small freshwater fish endemic to a handful of river basins in southeastern Brazil. Upon being first described, it was considered a member of genus Probolodus; Probolodus is now considered obsolete, synonymized with Deuterodon. Much like other members of Deuterodon, and like some species in related genera like Astyanax or Jupiaba, D. oyakawai is a silvery fish with fins in some combination of red and clear. It sports a wedge-shaped humeral spot, and an oval-shaped blotch on its tail joint.

References

  1. 1 2 Villa-Navarro, F.; Sanchez-Duarte, P. (2016). "Astyanax caucanus". IUCN Red List of Threatened Species . 2016: e.T49829978A61473673. doi: 10.2305/IUCN.UK.2016-1.RLTS.T49829978A61473673.en . Retrieved 24 August 2023.
  2. ↑ Reis, Roberto E.; Kullander, Sven O.; Ferraris Jr., Carl J. (2003). Check List of the Freshwater Fishes of South and Central America. Porto Alegre: Edipucrs. p. 108. ISBN   85-7430-361-5 . Retrieved 25 August 2023.
  3. ↑ Bailly, Nicolas (28 February 2022). "Astyanax caucanus (Steindachner, 1879)". WoRMS. World Register of Marine Species . Retrieved 26 August 2023.
  4. ↑ Rossini, Bruno César; Oliveira, Carlos Alexandre Miranda; Melo, Filipe Augusto Gonçalves de; Bertaco, Vinicius de Araújo; Astarloa, Juan M. Díaz de; Rosso, Juan J.; Foresti, Fausto; Oliveira, Claudio (19 December 2016). "Highlighting Astyanax Species Diversity through DNA Barcoding". PLOS ONE. 11 (12): e0167203. Bibcode:2016PLoSO..1167203R. doi: 10.1371/journal.pone.0167203 . PMC   5167228 . PMID   27992537.
  5. 1 2 Ruiz-C., R. I.; Román-Valencia, C.; Herrera-M., B. E.; Peláez, O. E.; Ermakova-A., A. (2011). "Variación morfológica de las especies de Astyanax, subgénero Zygogaster (Teleostei, Characidae)". Animal Biodiversity and Conservation. 34 (1): 47–66. doi: 10.32800/abc.2011.34.0047 . S2CID   82681421.
  6. 1 2 Eigenmann, Carl H.; Ogle, Fletcher (1908). "An annotated list of characin fishes in the United States National Museum and the Museum of Indiana University, with descriptions of new species". Proceedings of the United States National Museum. 33 (1556): 1–33. doi:10.5479/si.00963801.33-1556.1. ISSN   0096-3801. OCLC   1259735 . Retrieved 23 August 2023.
  7. ↑ "Astyanax panamensis (Günther 1864)". treatment.plazi.org. Plazi. 11 August 2021.
  8. ↑ Schmitter-Soto, Juan J. (6 May 2016). "A phylogeny of Astyanax (Characiformes: Characidae) in Central and North America". Zootaxa. 4109 (2): 101. doi:10.11646/zootaxa.4109.2.1.
  9. 1 2 3 Eigenmann, Carl H.; Myers, George S. (1921). The American Characidae. Vol. 43. Cambridge: Printed for the Museum. pp. 264–269. doi:10.5962/bhl.title.49183 . Retrieved 25 August 2023.
  10. ↑ Scharpf, Christopher; Lazara, Kenneth J. (29 December 2022). "Order CHARACIFORMES: Family CHARACIDAE: Subfamily STETHAPRIONINAE (a-g)". The ETYFish Project. Retrieved 24 August 2023.
  11. ↑ "Astyanax caucanus (Steindachner, 1879)". Encyclopedia of Life . National Museum of Natural History . Retrieved 24 August 2023.
  12. ↑ Fowler, Henry W. (1906). "Further Knowledge of Some Heterognathous Fishes. Part I". Proceedings of the Academy of Natural Sciences of Philadelphia. 58 (1): 343. Retrieved 26 August 2023.
  13. ↑ Froese, Rainer; Pauly, Daniel (eds.) (2023). "Astyanax caucanus" in FishBase . August 2023 version.
  14. ↑ "Astyanax caucanus (Steindachner, 1879)". Global Biodiversity Information Facility . Retrieved 26 August 2023.
  15. ↑ Eigenmann, Carl H. (October 1922). "The fishes of western South America. Part I. The fresh-water fishes of northwestern South America, including Colombia, Panama, and the Pacific slopes of Ecuador and Peru, together with an appendix upon the fishes of the Rio Meta in Colombia". Memoirs of the Carnegie Museum. 9 (1): 1–350. doi: 10.5962/p.234839 . S2CID   133685537 . Retrieved 26 August 2023.
  16. ↑ Riuz-C, Raquel I.; Román-Valencia, César; Taphorn, Donald C.; Buckup, Paulo A.; Ortega, Hernán (8 February 2018). "Revision of the Astyanax orthodus species-group (Teleostei: Characidae) with descriptions of three new species". European Journal of Taxonomy (402). doi: 10.5852/ejt.2018.402 .
  17. ↑ Roman Valencia, César (1990). "Lista y distribución de peces en la cuenca media del río atrato, chocó, colombia". Caldasia. 16 (77). Retrieved 26 August 2023.
  18. 1 2 Avendaño, Carlos Mario Marín; Ramírez, Néstor Jaime Aguirre (2017). "Spatial and temporal variation of fish assemblage associated with aquatic macrophyte patches in the littoral zone of the Ayapel Swamp Complex, Colombia". Acta Limnologica Brasiliensia. 29. doi: 10.1590/S2179-975X6016 . hdl: 10495/13207 .
  19. ↑ Espinel, Adriana; Valencia, José Luis (17 November 2007). "Al río Cauca lo están matando las 500 toneladas de contaminantes que le caen cada día". El Tiempo. Archived from the original on 19 November 2007. Retrieved 26 August 2023.{{cite news}}: CS1 maint: bot: original URL status unknown (link)
  20. ↑ Sánchez Torres, Luis Dario; Galvis Castaño, Alberto; Gandini, Mario Andres; Almario, Gloria; Montero, Maria Victoria; Vergara, María Virginia (14 April 2022). "Commission for the Upper Cauca River Basin Recovery, Collaborative Governance for Sustainability and Water Security". Frontiers in Water. 4. doi: 10.3389/frwa.2022.782164 .
  21. ↑ Salgado, Jorge; Shurin, Jonathan B.; Vélez, María I.; Link, Andrés; Lopera-Congote, Laura; González-Arango, Catalina; Jaramillo, Fernando; Åhlén, Imenne; de Luna, Gabriela (December 2022). "Causes and consequences of recent degradation of the Magdalena River basin, Colombia". Limnology and Oceanography Letters. 7 (6): 451–465. doi: 10.1002/lol2.10272 . S2CID   251125362.
  22. ↑ "Magdalena River Basin". nature.org. The Nature Conservancy. Retrieved 26 August 2023.
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