Astyanax biotae

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Astyanax biotae
Astyanax biotae.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. biotae
Binomial name
Astyanax biotae
Castro & Vari, 2004

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.

Contents

Though it is not studied well enough to have an official worldwide conservation status, researchers suggest a ranking of least concern for A. biotae, given a recently expanded native region and presence in several protected areas. Its original range was solely within the Brazilian state of Paraná; a 2018 study broadened this into São Paulo and Mato Grosso do Sul. It is not currently at risk of extinction, but A. biotae faces habitat loss, largely due to agricultural factors like destruction of the riparian zone and pollution from pesticides.

Taxonomy

Astyanax biotae was first described in 2004 by Brazilian ichthyologists Ricardo M. C. Castro and Richard P. Vari. [2] Since then, A. biotae has not undergone the same rigorous taxonomic evaluation that some congeners have. Astyanax bimaculatus , for example, has had as many as 14 names; [3] A. biotae has only ever had one. [4] [5] Though there are various species complexes recognized within the Astyanax genus, A. biotae is not currently assigned to any of them. [6]

Genetically, A. biotae is thought to be affiliated with congeners in a group that includes Astyanax dissimlis , Astyanax minor , and Astyanax scabripinnis . [7]

Etymology

The specific name biotae is in reference to Biota, the Virtual Biodiversity Institute Program, for its leadership in research, conservation, cataloging, and sustainable use of resources relating to biodiversity in Brazil. The genus name Astyanax is an allusion to the Iliad, wherein Astyanax was a Trojan warrior and son of Prince Hector. The specific reason for this allusion was not laid out in the original text, but modern research points to the scales of type species Astyanax argentatus , which are large and silvery like armor. [8]

Astyanax biotae has no common name. [9]

Description

Astyanax biotae is a small fish, reaching a maximum of 5.2 cm (2.0 in) standard length (SL). [10] There are 32–35 pored lateral-line scales, and the lateral line is complete. [11] There are 11 dorsal-fin rays, 12 or 13 pectoral-fin rays, 7 or 8 pelvic-fin rays, 27–30 anal-fin rays, and 19 caudal-fin rays. [12] The length of the body is roughly 2.5 to 3 times the depth; [11] the body shape is subrhomboidal. Sexual dimorphism is unknown.

The middle of the back is a yellowish-brown color that fades into a silvery-blue tinge on the sides; the belly is plain silver. The pelvic and pectoral fins are mostly clear with a mild yellow hue, and the dorsal and anal fins are slightly gray-blue with a dark margin. The caudal fin is also gray-blue, with slightly stronger coloration towards the ends of each lobe, and the middle caudal-fin rays are dark. [13] Some portions of the face and head are silvery, and the eyes have green highlights. [2] There is a single humeral spot that displays some vertical elongation, which can be used to tell it apart from several congeners that display horizontal elongation, such as members of the Astyanax bimaculatus species complex. [6] A. biotae also has a silver lateral stripe. [12] The scales of the flank have a dark-brown border. [5]

When preserved in alcohol, the majority of scale coloration disappears in favor of a uniform yellow-brown. [13] This is with the exception of an irregular dark-brown stripe down each side (silver in life), and a distinct dark spot on the caudal peduncle. [2]

Distribution and habitat

Astyanax biotae was originally described from a stream called Agua Mole in the Rio Paranapanema basin, in the Brazilian municipality Diamante do Norte of Paraná state. [2] At the time, it was thought to be endemic to the region, but future studies broadened its native range into the states of São Paulo and Mato Grosso do Sul. [6]

Riparian vegetation in areas that A. biotae inhabits often includes sparse forest and pastures, with a strong presence of pteridophytes (like ferns and horsetails) and grasses. [1]

Diet and ecology

Astyanax biotae feeds on invertebrates, aquatic detritus, seeds, and filamentous algae. [11] Its diet also includes fallen fruit, but it appears to be largely zooplanktivorous; in one study, more than 80% of the diet of examined specimens was composed of microcrustaceans, mainly from class Copepoda. Other food items include the larvae of Chironomidae (non-biting midges) and juveniles of Ephemeroptera (mayflies). [6]

Conservation status

In terms of global evaluation, the IUCN classes A. biotae as data deficient. Due to some modern doubts regarding its taxonomic validity, identified specimens are rare in some regions where sightings have been reported, and A. biotae is near impossible to evaluate as a result. [1] In the Mato Grosso do Sul State of Brazil, specifically, A. biotae has been determined to be a species of least concern, as of 2018. However, some of its habitat does face anthropogenic pressures, largely in the form of agriculture; deforestation (damaging the riparian zone), pesticide contamination, and excess sediment deposition have been recorded in some areas. Other locales, meanwhile, are in protected regions of the state. [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>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 tocantinensis</i> Species of fish

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.

<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 altiparanae</i> Species of fish

Astyanax altiparanae, sometimes called the yellow-tail tetra or yellow-tail lambari, is a species of schooling freshwater fish widely distributed across the southern half of South America. It is an ecologically flexible species, able to adapt to various resource and space conditions, and its diet follows this pattern; it is considered opportunistic and omnivorous. Its widespread nature and unspecified ecology contribute to its status as a species of least concern on the IUCN Red List. It was originally described from the upper Paraná river basin, which is the origin of its specific epithet; "alto" means "higher" in Brazilian Portuguese, hence "alto Paraná".

<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 bagual</i> Species of fish

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.

<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 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 chaparae</i> Species of fish

Astyanax chaparae, sometimes called the Chapare tetra, is a small species of freshwater fish only found in Bolivia. It is endemic to its type locality, the Río Chapare, which is a tributary of the Mamoré located in the Cochabamba department. Little else is known of its diet, behavior, and ecology. Its conservation status is similarly unclear, as the IUCN ranks it a data deficient species.

<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 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.

Astyanax anai is a small freshwater fish native to Central America. It has a restricted range, inhabiting a handful of Atlantic drainages in Costa Rica and Panama, and is known from locales only up to 100 meters elevation. As an endangered species, A. anai is a point of interest for conservation biologists studying the region. It can be found living sympatrically with other species of Astyanax, but is less common than its relatives.

References

  1. 1 2 3 Instituto Chico Mendes de Conservação da Biodiversidade (ICMBio) (2022). "Astyanax biotae". IUCN Red List of Threatened Species (in Portuguese). 2022: e.T187088A1822939. doi: 10.2305/IUCN.UK.2022-1.RLTS.T187088A1822939.pt . Retrieved 3 June 2023.
  2. 1 2 3 4 Castro, Ricardo M. C.; Vari, Richard P. (2004). "Astyanax biotae, A New Species Of Stream Fish From The Rio Paranapanema Basin, Upper Rio Parana System, Southeastern Brazil (Ostariophysi : Characiformes : Characidae)". Proceedings of the Biological Society of Washington. 117 (3): 330–338. Retrieved 3 June 2023.
  3. ↑ Bailly, Nicolas (2017). "Astyanax bimaculatus (Linnaeus, 1758)". WoRMS. World Register of Marine Species . Retrieved 3 June 2023.
  4. ↑ Bailly, Nicolas (2017). "Astyanax biotae Castro & Vari, 2004". WoRMS. World Register of Marine Species . Retrieved 3 June 2023.
  5. 1 2 "Astyanax biotae". Global Biodiversity Information Facility . Retrieved 2023-06-03.
  6. 1 2 3 4 Oliveira, Carlos Alexandre Miranda; Oliveira, Anielly Galego de; Pavanelli, Carla Simone (23 March 2018). "Expanding the geographical distribution of Astyanax biotae Castro & Vari, 2004 (Characiformes, Characidae), with comments on its conservation status". Check List. 14 (2): 387–392. doi: 10.15560/14.2.387 .
  7. ↑ 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.
  8. ↑ Scharpf, Christopher; Lazara, Kenneth J. (19 June 2024). "Family CHARACIDAE: Subfamily STETHAPRIONINAE Eigenmann 1907 (American Tetras)". The ETYFish Project. Retrieved 10 July 2024.
  9. ↑ "Astyanax biotae Castro & Vari 2004". Encyclopedia of Life . National Museum of Natural History . Retrieved 3 June 2023.
  10. ↑ Froese, Rainer; Pauly, Daniel (eds.). "Astyanax biotae". FishBase . June 2023 version.
  11. 1 2 3 Ota, Renata Rúbia; Deprá, Gabriel de Carvalho; Graça, Weferson Júnio da; Pavanelli, Carla Simone (11 June 2018). "Peixes da planície de inundação do alto rio Paraná e áreas adjacentes: revised, annotated and updated" (PDF). Neotropical Ichthyology. 16 (2). doi: 10.1590/1982-0224-20170094 . S2CID   90481718.
  12. 1 2 "Astyanax biotae Castro, Vari 2004 - Plazi TreatmentBank". treatment.plazi.org. Plazi TreatmentBank. Retrieved 3 June 2023.
  13. 1 2 3 Vilela, Maria José Alencar; Severo-Neto, Francisco; Carvalho, Fernando Rogério (29 November 2018). "Conservation status of Astyanax biotae (Characiformes: Characidae) in Mato Grosso do Sul, upper Paraná River basin, Brazil". Biotemas. 31 (4): 47–56. doi: 10.5007/2175-7925.2018v31n4p47 . S2CID   196671792.
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