Astyanax belizianus

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Astyanax belizianus
Astyanax belizianus preserved 3.png
A preserved specimen from the London Museum of Natural History
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Characiformes
Family: Characidae
Genus: Astyanax
Species:
A. belizianus
Binomial name
Astyanax belizianus
Bocourt, 1868
Synonyms

Tetragonopterus belizianus(Bocourt, 1868)

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.

Contents

Its original description nominated it as a member of genus Tetragonopterus , which is not uncommon for members of Astyanax named in the late 1800s. A. belizianus was considered synonymous with congener Astyanax aeneus for a great deal of its existence, but recent research into the phylogeny of the genus (2017) has resurrected it from synonymy and re-granted it species status.

Taxonomy

When originally described by French ichthyologist Marie Firmin Bocourt in 1868, A. belizianus was named Tetragonopterus belizianus. [1] By 1899, German-American ichthyologist Carl H. Eigenmann had synonymized it under congener Astyanax aeneus ; [2] at the time, A. aeneus was considered a subspecies of Astyanax fasciatus, a species that has since been renamed Psalidodon fasciatus. [3]

For a period in 1908, Astyanax aeneus was moved to genus Tetragonopterus as T. aeneus, and A. belizianus (Listed as T. belizianus) was still considered a synonym. [4] In 1997, A. belizianus had not been recognized, but A. aeneus had been moved back into Astyanax; Mexican ichthyologist Juan J. Schmitter-Soto performed a thorough examination of the genus in 2017 and revived the specific epithet belizianus, placing it in the genus Astyanax for the first time, which is where the species currently stands. [5]

The original description was sparse, but noted upon a similarity to congener Astyanax panamensis , also a member of Tetragonopterus at the time. [6]

Etymology

The specific name belizianus means "belonging to Belize", in reference to the type locality. The genus name Astyanax is an allusion to the Iliad, wherein Astyanax was a Trojan warrior and the son of prince Hector. The specific reasons for this allusion were not made clear in the nominal paper, but a potential origin is in the scales of the type species, Astyanax argentatus , which are large and silvery in a way that could be compared to armor or a shield. [7]

Due to its scientific name and type locality, A. belizianus is sometimes referred to as the Belizean tetra. [8]

Description

Astyanax belizianus is roughly 9.7 cm (3.8 in) total length, TL (with the tail fin included, as opposed to standard length, SL, without the tail fin). [9] Some larger specimens can reach 10.9 cm (4.3 in) SL. [10] The body is deep, which reportedly becomes more noticeable upon comparison to congeners. [11] There are 10 dorsal-fin rays (occasionally 9), 22–29 anal-fin rays (with a mean of 26), and 11–12 pectoral-fin rays. There are 32–39 lateral-line scales, most often 36. [5]

Its back is a slate-gray, its sides are tinged yellow, and the underside is gray. [12] There is a dark blotch of pigment on the caudal peduncle and caudal fin. [13] There is a single humeral spot, which can be p-shaped or indistinct. [5] There is a lateral stripe of bright, reflective scales in greenish or yellowish on both flanks. [14] When preserved in alcohol, the scales turn uniformly brassy, with a broad stripe down the side that is slightly paler. [9]

Astyanax belizianus is morphologically similar to various other species of Astyanax, such as A. aeneus and A. panamensis. Until 2021, at least one specimen of A. belizianus was mistakenly included in the type series for A. aeneus, [15] and several syntypes of A. panamensis have since been determined to be A. belizianus instead. [13]

Sexual dimorphism

Mature males display tiny protrusions, called nuptial tubercles, on the head and scales. These are always simple, which means that they are in one piece, as opposed to bifid, split down the middle. [10] Otherwise, little is known of differentiating coloration or morphometric aspects between the sexes.

Distribution and ecology

The specific type locality is unknown; Bocourt's 1868 description simply stated "Environs de Belize". [6] Since then, the range of A. belizianus has been elaborated upon. Starting in the Mullins River of central Belize, it extends south to tributaries of Lake Izabal, in Guatemala and northern Honduras. [1] Specific biotope preferences are unknown, as are diet and sympatry, though there is the possibility that records have been made while A. belizianus was grouped under A. aeneus.

Conservation status

Astyanax belizianus has not been evaluated by the IUCN. [8] Members of Astyanax as a whole are generally hardy and adaptive, but A. belizianus inhabits localities that face both natural and anthropogenic environmental pressures.

The Mullins River area is subject to hurricanes, which has a recorded impact on the geoscape, including surface sediments; [16] this, in turn, can impact water quality. Lake Izabal generally resists sediment disturbance thanks to the nearby wetlands, but has been subject to human pollution in modern times, largely due to mining activity. [17] One element to consider is that, due to the presence of both an inlet river and an outlet river, the water of the lake is totally replaced, or "cycled", every 6.6 months; [18] it is unknown what impact this has on its tributaries, if any.

Related Research Articles

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

Astyanax acatlanensis, sometimes called the Acatlán tetra, is a small species of fish from the rivers of Mexico. It is a relatively hardy species that is able to tolerate a variety of water conditions, but is only found in freshwater, never brackish or marine. It is known only from the Río Acatlán, which is its type locality, and the Río Jía, which is a small, unknown river in the Oaxaca region.

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

Astyanax aeneus, the banded tetra, is a small species of fish native to southern Central America and northern South America. It can be found in a variety of environments, including lakes, rivers, ponds, and slightly brackish locales like lagoons. As well as a varied habitat, it has a varied omnivorous diet: algae, seeds, leaves, insects, and fish fry appear to be the most common.

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

Astyanax altior, the Yucatán tetra, is a small species of freshwater fish endemic to the Yucatán Peninsula of Mexico. It largely inhabits the cenotes of the region, and can tolerate water of limited salinity, though it largely prefers freshwater. Its diet includes plant matter and invertebrates, and there may be an element of cannibalism involved.

<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 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 bacalarensis</i> Species of fish

Astyanax bacalarensis, sometimes referred to as the Bacalar tetra, is a small species of freshwater fish found in Central and South America. Its scientific and common names both refer to its type locality, Lake Bacalar in Mexico, and it further inhabits freshwater environments like cenotes, streams, and wetlands. Its widespread nature, paired with an omnivorous diet, make it a hardy species.

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

Astyanax baileyi is a small freshwater fish native to northern Guatemala. Based on several visual aspects, it was once considered a member of the genus Bramocharax, which is now obsolete, and has since been synonymized with Astyanax. As such, former members of Bramocharax are now a part of Astyanax, like Astyanax bransfordii and Astyanax caballeroi.

<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.

Astyanax bransfordii, sometimes called the longjaw tetra, is a small carnivorous species of fish endemic to a handful of lakes and slow-moving canals in Central America. Its range includes Lake Nicaragua and Lake Managua, which are two of the largest freshwater bodies in Central America; because it occurs only in the relevant areas of Costa Rica and Nicaragua, the area it actually inhabits is somewhat restricted. Its diet largely consists of various invertebrates and smaller fish. This is in contrast to various other species of Astyanax, which are more often omnivorous.

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

Astyanax brevimanus, sometimes referred to as the Quiché tetra, is a small species of freshwater fish native to various locales in Guatemala. Its native range is somewhat restricted, but it is a populous and adaptable species, so there is no risk of it going extinct anytime soon. It is unknown what A. brevimanus eats, or what specific habitats it prefers; current information is largely in the form of physical descriptions, general areas of occurrence, and hypotheses regarding relationships to congeners. Its silvery scales, indistinct humeral (shoulder) spot, and dark caudal-peduncle spot are features not unusual in species of Astyanax.

<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>Astyanax caballeroi</i> Species of fish

Astyanax caballeroi is a small species of freshwater fish endemic to a single lake system in Mexico. It has a longer snout and more slender body than most other species in the genus Astyanax, thought to be the result of predatory behavior; while A. caballeroi eats invertebrates and smaller fish, other Astyanax species are more broadly omnivorous, and have deeper bodies with shorter snouts. This difference in body shape once placed A. caballeroi, along with several other species of Astyanax, into the former genus Bramocharax.

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

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.

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

Deuterodon heterostomus is a small species of characin endemic to a large river system in southeast Brazil. It was originally the only member of the genus Probolodus, but Probolodus is now considered obsolete, synonymized with Deuterodon. Much like other members of Deuterodon, and like some fish in related genera, D. heterostomus is a small, silvery fish with fins in some combination of red and clear. It has a defined humeral spot that can be used for identification.

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

Deuterodon oyakawai is a small species of characin endemic to a large river basin along the Atlantic coast in southeast Brazil. It was originally one of three members of the genus Probolodus, but Probolodus is now considered obsolete, synonymized with Deuterodon. Much like other members of Deuterodon, and like some species in related genera, D. oyakawai is a small, silvery fish with fins in some combination of red and clear. It has a defined humeral spot that can be used for identification.

<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 Eschmeyer, William N.; Fricke, Ron & van der Laan, Richard (eds.). "Species related to Astyanax belizianus". Catalog of Fishes . California Academy of Sciences . Retrieved 29 May 2023.
  2. ↑ Hatcher, J. B.; Morgan, J. Pierpont; Scott, William Earl Dodge; Scott, William Berryman; Sharpe, Richard Bowdler; Stone, Witmer.; Allen, J. A.; Stejneger, Leonhard; Eigenmann, Carl H. (1901). Reports of the Princeton University Expeditions to Patagonia, 1896-1899. J. B. Hatcher in charge. Princeton: The University. p. 433. Retrieved 29 May 2023.
  3. ↑ Bailly, Nicolas (2021). "Psalidodon fasciatus (Cuvier, 1819)". WoRMS. World Register of Marine Species . Retrieved 30 May 2023.
  4. ↑ "Biologia Centrali Americana Zoology, Botany, and Archæology". Nature. 96 (2408): 170. 1915. doi:10.1038/096448a0. ISSN   0028-0836 . Retrieved 29 May 2023.
  5. 1 2 3 Schmitter-Soto, Juan J. (2017-06-26). "A revision of Astyanax (Characiformes: Characidae) in Central and North America, with the description of nine new species". Journal of Natural History. 51 (23–24): 1331–1424. doi:10.1080/00222933.2017.1324050. ISSN   0022-2933.
  6. 1 2 Bocourt, M. F. (1868). "Note sur les poissons du genre Tétragonoptère provenant du Mexique et du Guatemala". Annales des sciences naturelles Zoologie. 5 (9): 61. Retrieved 29 May 2023– via BHL.
  7. ↑ Scharpf, Christopher; Lazara, Kenneth J. (28 December 2023). "Family CHARACIDAE: Subfamily STETHAPRIONINAE Eigenmann 1907 (American Tetras)". The ETYFish Project. Retrieved 27 January 2023.
  8. 1 2 Froese, Rainer; Pauly, Daniel (eds.) (2023). "Astyanax belizianus" in FishBase . May 2023 version.
  9. 1 2 "1907.4.10.3". data.nhm.ac.uk. 1 February 2021. Retrieved 29 May 2023.
  10. 1 2 "Astyanax belizianus - Plazi TreatmentBank". treatment.plazi.org. Retrieved 2023-05-30.
  11. ↑ Pamphlets on forestry. Fish and game. 1900. p. 336. doi:10.5962/bhl.title.30796.
  12. ↑ Pellegrin, Jacques (1903). "Poissons récoltés dans l'Ouellé, par la mission du Bourg de Bozas". Bulletin du Musée D'histoire Naturelle. 9 (7): 326. Retrieved 29 May 2023– via BHL.
  13. 1 2 "Astyanax panamensis - Plazi TreatmentBank". treatment.plazi.org. Retrieved 2023-05-30.
  14. ↑ Schmitter-Soto, Juan J. (2017-07-03). "Figure 25 in A revision of Astyanax (Characiformes: Characidae) in Central and North America, with the description of nine new species". doi:10.5281/zenodo.5181939 . Retrieved 2023-05-30.
  15. ↑ Schmitter-Soto, Juan J. (2021-05-03). "New lectotype designation for Astyanax aeneus (Teleostei: Characidae)". Journal of Natural History. 55 (17–18): 1071–1073. doi:10.1080/00222933.2021.1933231. ISSN   0022-2933.
  16. ↑ McCloskey, T.A.; Keller, G. (February 2009). "5000 year sedimentary record of hurricane strikes on the central coast of Belize". Quaternary International. 195 (1–2): 53–68. doi:10.1016/j.quaint.2008.03.003.
  17. ↑ Hernández, Elisandra; Obrist-Farner, Jonathan; Brenner, Mark; Kenney, William F.; Curtis, Jason H.; Duarte, Edward (November 2020). "Natural and anthropogenic sources of lead, zinc, and nickel in sediments of Lake Izabal, Guatemala". Journal of Environmental Sciences. 96: 117–126. doi:10.1016/j.jes.2020.04.020.
  18. ↑ RobledoI, José; Chacón, Eddi; García Álvarez, Nancy (2014). "La calidad del agua del lago de Izabal, Guatemala. Relaciones temporales y espaciales de variables físico-químicas y biológicas". Revista Ciencias Técnicas Agropecuarias. 23 (4): 28–32. Retrieved 29 May 2023.
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