Astyanax bagual

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Astyanax bagual
Astyanax bagual.png
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Characiformes
Family: Characidae
Genus: Astyanax
Species:
A. bagual
Binomial name
Astyanax bagual
Bertaco & Vigo, 2015

Astyanax bagual is a small species of freshwater fish known only from the Taquari-Antas river basin in southern Brazil. It is unusual in the genus Astyanax because mature male specimens display bony hooks on the rays of all fins; in opposition, most others have them on the anal, pelvic, or pectoral fins - sometimes on more than one of these, but very rarely on all fins. It can further be told apart from various congeners by way of dentition and some aspects of coloration, including the presence of two humeral spots instead of one (which is more common).

Contents

Though it lives in a somewhat restricted area, A. bagual is thought to be more widespread than has been recorded. As well as this, it bears physiological similarities to several congeners known to be resilient and adaptable. As such, despite not being evaluated officially by the IUCN, A. bagual is generally considered a species of least concern. Other than this, little research has been done regarding its ecology, including diet and sympatric species.

Taxonomy

Astyanax bagual was described in 2015 by Brazilian researchers Vinícius A. Bertaco and Anelise C. Vigo. [1] The possibility of more than one unnamed Astyanax species native to the Taquari-Antas river basin, the type locality of A. bagual, was remarked upon in a study of the relevant ichthyofauna in 2013. [2] Despite the cryptic nature of the genus Astyanax as a whole, A. bagual is not currently considered to be a part of any species complex; [3] various congeners found within a similar range are mostly within the complex centering on Astyanax scabripinnis , such as A. obscurus , A. ojiara , and A. paris . [4] However, based on analysis of various synapomorphies, A. bagual is likely to form a clade with A. chico and A. troya . [5]

Etymology

The genus name "Astyanax" is an homage to the Greek figure Astyanax, a warrior and the son of Trojan prince Hector. This possibly originates in the armor-like scales of type species Astyanax argentatus , which are plate-like and silver, but the reasoning was not made clear in the original text. The specific name "bagual" is a Tupí-Guaraní word meaning "wild horse", specifically a sexually mature wild stallion with the associated aggressive temperament. This is an allusion to the presence of bony hooks on all fins of mature male A. bagual. [6]

Astyanax bagual currently lacks a common name and has no known synonyms. [7]

Description

Astyanax bagual reaches 7.8 cm (3.1 in) standard length (SL), with a rather compressed body of moderate depth. [8] It has 24-28 branched anal-fin rays, 11–13 pectoral-fin rays, and 7 pelvic-fin rays. The lobes of the caudal fin have either 10 or 11 rays each.There are 37–39 perforated lateral line scales, and 14 scale rows around the caudal peduncle (circumpeduncular scales). [9] There are 2–4 tricuspid maxillary teeth, [10] which can be used as a differentiating feature; similar congeners more often have just one. [1]

Its body is largely silver with a slightly darker back and underside, as well as a touch of yellowish or brown on most scales. The dorsal, ventral, pectoral, and adipose fins are all yellow towards the front and red towards the back, and the caudal fin is largely red with a yellowish central portion. The anal fin is mostly yellow with a spot of bright red on the first few rays. [5] A. bagual has two humeral spots, the foremost of which is vertically elongated and wider at the top than the bottom. The second humeral spot is large and sometimes inconspicuous, blending in with a dark lateral stripe, as well as positioned higher than the first (does not extend below the lateral line). [8] The lateral stripe never touches the foremost of the two spots, but always starts at the second, and terminates in a conspicuous blotch of pigment on the caudal peduncle. [11] This caudal peduncle spot continues onto the middle rays of the caudal fin. [9]

Sexual dimorphism

All mature male specimens of A. bagual develop bony hooks on the first few rays of every fin. [5] This is an unusual feature within the genus; most other species that display similar dimorphism have hooks restricted to the anal, pelvic, and/or pectoral fins. [10]

Distribution and ecology

Astyanax bagual is only known from the Taquari-Antas basin of the Rio Jacuí drainage, which is a part of the laguna dos Patos system in the Rio Grande do Sul state of southern Brazil. [9] It is most often found in smaller rivers up to two meters deep with rocky substrate, and seems to prefer areas of moderate riparian vegetation. [1] A. bagual has been collected at altitudes from 179 m to roughly 300 m above sea level. [5] [12]

Little is known of A. bagual's diet and interaction with sympatric life, but it is parasitized by Monogenean species Characithecium chascomusensis. [12] The riparian zones in A. bagual's native range include Atlantic forests and natural grasslands; the environment therein faces some survival pressure due to human activity. [2]

Conservation status

Astyanax bagual has not been evaluated by the IUCN. [1] It is not thought to be in any imminent danger of extinction, given its similarity to hardy congeners and the suspicion of a wider range than has currently been identified. [5] Still, the Taquari-Antas basin faces anthropogenic pressures, largely in the form of river damming for hydroelectric power generation; in 2010, there were 26 active dams in the basin, and 80 other sites being surveyed for potential construction of new power plants. [2] An example of dam placement changing an aquatic environment can be seen in the Xingu River, another Brazilian river with diverse ichthyofauna. Construction of the Belo Monte dam, the most prominent power station along its length, radically altered the river's flow. [13]

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>Ectrepopterus</i> Species of fish

Ectrepopterus uruguayensis is a small species of characin originally recorded only from streams in Uruguay, with occasional sightings in Brazil and Argentina. It is the only known member of the genus Ectrepopterus, which was formerly a subgenus of Megalamphodus. Given its restricted range, it is considered a rare fish, and is of note for conservation researchers interested in preserving the biodiversity of the region.

Astyanax microschemos is a species of characid fish from Brazil. It belongs to the A. scabripinnis species complex and differs from other species outside it by having a lower number of branched anal fin rays and its shallow body depth being about 26.9-29.7 vs more than 35% of its standard length (SL). Compared to species of its own complex, it can be distinguished by the combination of its shallow body depth, and smaller interorbital width. The species name comes from the Greek mikroschemos, meaning "low stature", which refers to the shallow body depth of the animal.

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

Deuterodon pelecus is a species of characid fish from Brazil. It can be distinguished from other species by: its body depth ; its short and pointed snout smaller than the orbital diameter; and a reduced number of branched anal fin rays. D. pelecus also differs from members of its genus by its characteristic color pattern. It possesses a single humeral spot that is constricted to the region above the lateral line; at the same time it shows a conspicuous midlateral body stripe from opercle to the caudal fin base, an autapomorphy of this precise species. Other Deuterodon species have a humeral spot that is vertically or horizontally elongate and have the midlateral stripe becoming faint near that humeral spot. The species name is derived from the Greek pelekus, meaning "axe", referring to the pigmentation shape resulting from the adjoinment of the humeral spot with the midlateral stripe.

<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 abramis</i> Species of fish

Astyanax abramis is a small freshwater fish from the inland rivers of South America. It is plentiful in almost the entire continent, with a habitat including the La Plata, upper Amazon, and Meta River basins. The body shape is subrhomboidal and laterally compressed, and the scales are largely silver, with a blue or green tint on the dorsal side.

<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 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 biotae</i> Species of fish

Astyanax biotae is a small species of freshwater fish native to various localities in Brazil. It primarily eats invertebrates, like copepods and aquatic fly larvae, and its diet also includes seeds, fruits, and filamentous algae. Its scales are largely silver, with a touch of yellow-brown on the back and a hint of blue on the sides. Like many species of Astyanax, it has a humeral spot, which is a blotch of pigmentation in the area above or around the pectoral fin.

<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.

Astyanax apiaka is a small freshwater fish endemic to the Apiacá river in Mato Grosso, Brazil. Its discovery is recent, as of 2023, which results in little published research of its natural behaviors or preferred biotopes. However, descriptions of its appearance and general environment have been solidified, as well as some baseline information regarding its diet. It lacks a conservation status from the IUCN.

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

Astyanax clavitaeniatus is a small species of freshwater fish native to various rivers in the Amazon basin. It is characterized by a club-shaped lateral stripe, which is where it gets its scientific name; "clava" means "club", and "taenia" means "stripe". It is a deep-bodied fish with a silvery base color, which is not uncommon for members of Astyanax. Its markings - including a humeral spot and two vertical brown bars - indicate that it is a part of a species complex centered around congener Astyanax bimaculatus.

<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 3 4 Froese, Rainer; Pauly, Daniel (eds.) (2023). "Astyanax bagual" in FishBase . May 2023 version.
  2. 1 2 3 Becker, Fg.; De, Fries LCC.; Ferrer, J.; Bertaco, Va.; Luz-Agostinho, Kdg.; Silva, Jfp; Cardoso, Ar.; Lucena, Zms.; Lucena, Cas. (February 2013). "Fishes of the Taquari-Antas river basin (Patos Lagoon basin), southern Brazil". Brazilian Journal of Biology. 73 (1): 79–90. doi: 10.1590/S1519-69842013000100010 . hdl: 10183/115511 . PMID   23644791.
  3. ↑ da Graça, W. J.; Oliveira, C. A. M.; Lima, F. C. T.; da Silva, H. P.; Fernandes, I. M. (October 2017). "A new species of Astyanax (Characiformes: Characidae) from Dolina Água Milagrosa, Rio Paraguai basin, Mato Grosso, Brazil". Journal of Fish Biology. 91 (4): 1123–1138. doi:10.1111/jfb.13405. PMID   28868674.
  4. ↑ de Lucena, Carlos Alberto S.; Zaluski, Amanda Bungi; de Lucena, Zilda Margarete Seixas (18 September 2017). "Astyanax taurorum a new species from dos Touros River, Pelotas River drainage, an upland southern Brazilian river (Characiformes: Characidae)". Zoologia. 34: 1–8. doi: 10.3897/zoologia.34.e20174 .
  5. 1 2 3 4 5 Bertaco, Vinícius A.; Vigo, Anelise C. (June 2015). "A new species of Astyanax Baird & Girard (Ostariophysi: Characidae) from the rio Taquari-Antas basin, southern Brazil". Neotropical Ichthyology. 13 (2): 265–272. doi:10.1590/1982-0224-20140145.
  6. ↑ Scharpf, Christopher; Lazara, Kenneth J. (29 December 2022). "Order CHARACIFORMES: Family CHARACIDAE: Subfamily STETHAPRIONINAE (a-g)". The ETYFish Project. Retrieved 3 May 2023.
  7. ↑ "Astyanax bagual Bertaco & Vigo 2015". Encyclopedia of Life . National Museum of Natural History . Retrieved 8 May 2023.
  8. 1 2 Bertaco, Vinícius A.; Vigo, Anelise C. (30 June 2015). "Astyanax bagual Bertaco & Vigo 2015, new species". zenodo.org. doi:10.5281/zenodo.4776208 . Retrieved 9 May 2023.
  9. 1 2 3 "Astyanax bagual, Bertaco & Vigo, 2015". treatment.plazi.org. Plazi TreatmentBank. Retrieved 9 May 2023.
  10. 1 2 Oliveira, Carlos Alexandre Miranda (2017). Revisão taxonômica do complexo de espécies Astyanax scabripinnis sensu Bertaco & Lucena (2006) (Ostariophysi: Characiformes: Characidae) (PhD Dissertation). Universidade Estadual de Maringá. hdl:1834/10128 . Retrieved 8 May 2023.
  11. ↑ Dagosta, Fernando C. P.; Marinho, Manoela M. F. (2022). "New small-sized species of Astyanax (Characiformes: Characidae) from the upper rio Paraguai basin, Brazil, with discussion on its generic allocation". Neotropical Ichthyology. 20 (1): e210127. doi: 10.1590/1982-0224-2021-0127 . S2CID   247654552.
  12. 1 2 Wendt, Emília W.; Malabarba, Luiz R.; Braga, Mariana P.; Boeger, Walter A.; Landis, Michael; Carvalho, Tiago P. (3 March 2022). "Phylogeny, species delimitation and ecological and morphological diversity of Characithecium (Monogenoidea: Dactylogyridae)". Parasitology: 1–17. doi:10.1017/S0031182022000221. PMID   35236513. S2CID   247219893.
  13. ↑ Hansen, Kathryn (6 October 2017). "Reshaping the Xingu River". earthobservatory.nasa.gov. NASA Earth Observatory Archive. Retrieved 26 April 2023.
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