Ectrepopterus

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Ectrepopterus
Ectrepopterus uruguayensis (46313).jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Characiformes
Family: Characidae
Genus: Ectrepopterus
Fowler, 1943
Species:
E. uruguayensis
Binomial name
Ectrepopterus uruguayensis
Fowler, 1943
Synonyms [2]

Hyphessobrycon uruguayensis(Fowler, 1943)
Megalamphodus uruguayensis(Fowler, 1943)

Contents

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 (now known as Hyphessobrycon ). 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.

A small fish with silvery-gold scales and yellow fins, E. uruguayensis is characterized by a variety of features, including an incomplete lateral line and eyes wider than the snout is long. Something of particular note is the presence of bony hooks on the fin-rays of the pectoral fin, which is unusual for a characin; other members of Characidae may display these hooks on the pelvic or anal fins, but the pectoral fin is an uncommon location. E. uruguayensis can be found living in syntopy with other characids in the wild, such as the genera Bryconamericus and Astyanax, and has a preference for shallow, flowing waters with ample vegetation.

Taxonomy

When originally described by American ichthyologist Henry Weed Fowler in 1943, E. uruguayensis was named Megalamphodus (Ectrepopterus) uruguayensis, placing Ectrepopterus as a subgenus instead of a full genus. [3] In 1997, Megalamphodus was determined to be synonymous with Hyphessobrycon , though the researchers (Lisa Palmer and Stanley Weitzman) noted that this was in need of further research. [4] [5] Nonetheless, this decision has generally been upheld, and Megalamphodus remains a synonym of Hyphessobrycon to this day. [6] E. uruguayensis was considered a member of Hyphessobrycon from 1997 onwards, under the name Hyphessobrycon uruguayensis, but research in 2012 overturned this and resurrected Ectrepopterus from synonymy, designating E. uruguayensis the sole member. [5] [7]

When E. uruguayensis was still a member of Megalamphodus, French ichthyologist Jacques Gery noted a potential relationship to M. micropterus ( Hyphessobrycon micropterus ) and M. sweglesi ( Hyphessobrycon sweglesi ) based upon morphometric characteristics. [8] Given different generic designations, E. uruguayensis is, in reality, unlikely to share elements of close phylogeny with the other two species.

Etymology

The genus name originates in Greek. "Ectrepos" means "reversed", and "pterus" means "fin" or "wing", in reference to the caudal fin; the upper lobe is shorter than the lower. The suffix "-ensis" denotes a location, and E. uruguayensis was originally described from Uruguay. [9]

Ectrepopterus uruguayensis lacks a common name, but is referred to under the general "tetra" label in English and the "mojarra" label in Spanish. [10]

Description

Ectrepopterus uruguayensis reaches a maximum of 5.1 cm (2.0 in) SL (standard length, without the tail fin included). [11] The body is elongated and horizontally compressed, and is deepest within the range of the dorsal-fin origin. The caudal peduncle is relatively long and usually straight, occasionally with slight concavity above and below. [12] The eye is wider than the snout is long, and the lower jaw protrudes slightly past the upper. [3] The lateral line is incomplete, with 5–9 pored scales (most often 6). [12]

There are 10–12 dorsal-fin rays (ii, 8–10 - meaning two unbranched rays and 8 to 10 branched rays), 11–13 pectoral-fin rays (i, 10–12), 7 or 8 pelvic-fin rays (i, 6 or 7), and 22–31 anal-fin rays (iii–v, 19–26). [13] There are hooks on the pectoral-fin rays; while hooks on various fin-rays are common in various characid species, their presence on the pectoral fin in particular is unusual, and can be used as diagnostic criteria for E. uruguayensis when compared to similar species. [5] The lower lobe of the caudal fin is sometimes longer than the upper, which Fowler cited amongst further diagnostic criteria; however, this is not uncommon in small characins, and is not present in all specimens of E. uruguayensis. As such, it should not be regarded as a distinguishing feature, though it is of occasional note during research. [14]

The base scale color for E. uruguayensis ranges from silvery-yellow to golden, with scattered dark-brown dots on the top and sides of the head and body. There is a single humeral spot, vertically elongated, positioned over the third or fourth lateral-line scale; this spot extends over one or two of the scale rows above and below the line. There is a narrow lateral stripe that starts in the middle of the back half of the body and extends to the base of the middle caudal-fin rays, expanding on the caudal peduncle itself to form a triangle-shaped spot. The midlateral portion of the body also has a row of chevron-shaped marks pointing forward. [5]

All fins sport scattered black chromatophores (pigment cells), but have varying base colors; the dorsal fin is yellowish, as are the caudal fin and adipose fin. The tips of the caudal-fin rays are darkened, and the middle rays have scattered black dots due to the melanophores there (black pigment cells, specifically).The pectoral fins are hyaline (clear); the ventral fin is orangish. [12]

This specimen is a female, as can be told by the smooth concavity of the anal fin. Ectrepopterus uruguayensis (ILPLA 1817).png
This specimen is a female, as can be told by the smooth concavity of the anal fin.

When preserved in alcohol, the top and sides of the head and body turn brown, still with the scattered dark-brown dots of a living specimen. Other elements of the general pattern remain similar to those in life. In larger specimens (above 3.50 cm (1.38 in) SL), the upper and lower borders of the scales are darkened, which forms a wavy pattern that becomes more prominent in the middle of the body; this is not as obvious in living specimens. [13] The fins are a pale gray-brown. [3] The holotype - the original preserved individual of the species - is discolored, and has a more diffuse pattern than a normal specimen (with the sole exception of the humeral spot, which remains pigmented). [13]

Sexual dimorphism

Mature males of E. uruguayensis display small bony hooks on all fin-rays, while females do not. Females sport a concave anal-fin profile, where it is almost straight in males. Other dimorphisms, such as morphometric or coloration differences, are absent between the sexes. [7]

Distribution and ecology

Ectrepopterus uruguayensis was originally described from Uruguay, though Fowler failed to provide specific details. [3] For a period of roughly 20 years from 1990 to 2010, there were no records of the species anywhere else; before then, there were instances of occasional specimens from the portion of the Río Uruguay in Brazil. [11] A 2013 report of specimens found in Argentina broadened this range somewhat, [14] and specimens were rediscovered in the Pampas region of Brazil in May 2023, again expanding the known range. [7] Still, the area of occurrence remains relatively restricted.

Generally, E. uruguayensis displays a preference for streams, and occurs in shallow areas (less than 1 m depth) with a notable current, though it has been cited from semi-still waters and areas of up to 2 m depth. [7] [14] It is found in regions with aquatic and riparian vegetation both. [5] While it has its preferences, it also demonstrates some adaptability to weather conditions that influence its habitat; for instance, heavy rainfall may result in turbid water with a muddy substrate, while a drought might result in transparent water and a depth as little as 30 cm (12 in). [7]

Ectrepopterus uruguayensis is a generally amicable fish that occurs in low-density populations, with an extensive list of syntopic species from various fish families. Syntopic species also in the family Characidae, to which E. uruguayensis belongs, include Bryconamericus stramineus , Charax stenopterus , Cheirodon interruptus , Diapoma terofali , Oligosarcus jenynsii , and at least three species of Astyanax. Other fishes from various families include Cyphocharax spilotus and Steindachnerina biornata (from family Curimatidae); Characidium rachovii and Characidium tenue (family Crenuchidae); Hoplias malabaricus (Erythrinidae); Hisonotus maculipinnis and Hypostomus commersoni (Loricariidae); Cnesterodon decemmaculatus (Poeciliidae); and Australoheros facetus , Australoheros scitulus , Crenicichla scottii , and Gymnogeophagus meridionalis (Cichlidae). [14] Hoplias malabaricus in particular, also called the trahira, is likely to be a predator of E. uruguayensis, given that it regularly preys on other small characids, such as members of Hyphessobrycon and Astyanax. [15]

Other details are sparse, regarding aspects such as diet, behavior, and mating habits.

Conservation status

Ectrepopterus uruguayensis is considered Near Threatened by the IUCN. [1] It is considered a priority species for conservation action, as it is generally thought to be a rare fish, given its restricted range and that it normally occurs in low densities. [7] Because it was long considered to be endemic to Uruguay, it is eligible for protection under SNAP (Sistema Nacional de Áreas Protegidas, or System of National Areas under Protection), which provides a buffer against potential survival pressures. [16]

Related Research Articles

<span class="mw-page-title-main">Characidae</span> Family of fishes

Characidae, the characids or characins, is a family of freshwater subtropical and tropical fish belonging to the order Characiformes. The name "characins" is an historical one, but scientists today tend to prefer "characids" to reflect their status as a, by and large, monophyletic group. To arrive there, this family has undergone much systematic and taxonomic change. Among those fishes remaining in the Characidae currently are the tetras, comprising the very similar genera Hemigrammus and Hyphessobrycon, as well as a few related forms, such as the cave and neon tetras. Fish of this family are important as food in several regions, and also constitute a large percentage of captive freshwater aquarium fish species.

<span class="mw-page-title-main">Tetra</span> Common name for several species of fish

Tetra is the common name of many small freshwater characiform fishes. Tetras come from Africa, Central America, and South America, belonging to the biological family Characidae and to its former subfamilies Alestidae and Lebiasinidae. The Characidae are distinguished from other fish by the presence of a small adipose fin between the dorsal and caudal fins. Many of these, such as the neon tetra, are brightly colored and easy to keep in captivity. Consequently, they are extremely popular for home aquaria.

<i>Hyphessobrycon</i> Genus of fishes

Hyphessobrycon is a genus of freshwater fish in the family Characidae. These species are among the fishes known as tetras. The genus is distributed in the Neotropical realm from southern Mexico to Río de la Plata in Argentina. Many of these species are native to South America; about six species are from Central America and a single species, H. compressus is from southern Mexico.

<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.

<span class="mw-page-title-main">Flame tetra</span> Species of fish

The flame tetra, also known as the red tetra or Rio tetra, is a small freshwater fish of the characin family Characidae. This tetra was first introduced as aquarium fish in 1920 by C. Bruening, Hamburg, Germany, and formally described in 1924 by Dr. George S. Myers. Today large numbers are bred in captivity and it is common in the aquarium trade, but the remaining wild population in Southeast Brazil is highly threatened.

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>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 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 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 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 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 bourgeti</i> Species of fish

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<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.

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 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.

References

  1. 1 2 Loureiro, M. & Bessonart, J. (2023). "Ectrepopterus uruguayensis". IUCN Red List of Threatened Species . 2023: e.T178304351A178304532. doi: 10.2305/IUCN.UK.2023-1.RLTS.T178304351A178304532.en . Retrieved 19 March 2024.
  2. ↑ "Ectrepopterus uruguayensis". Global Biodiversity Information Facility . Retrieved 2023-10-13.
  3. 1 2 3 4 Fowler, Henry W. (1943). "Notes and Descriptions of New or Little Known Fishes from Uruguay". Proceedings of the Academy of Natural Sciences of Philadelphia. 95: 311–346. ISSN   0097-3157 . Retrieved 13 October 2023.
  4. ↑ Weitzman, Stanley H.; Palmer, Lisa (1997). "A new species of Hyphessobrycon (Teleostei: Characidae) from the Neblina region of Venezuela and Brazil, with comments on the putative 'rosy tetra clade'". Ichthyological Exploration of Freshwaters. 7 (3): 209–242.
  5. 1 2 3 4 5 Malabarba, Luiz R.; Bertaco, Vinicius A.; Carvalho, Fernando R.; Litz, Thomas O. (23 February 2012). "Revalidation of the genus Ectrepopterus Fowler (Teleostei: Characiformes), with the redescription of its type species, E. uruguayensis". Zootaxa. 3204 (1): 47. doi: 10.11646/zootaxa.3204.1.5 .
  6. ↑ Bailly, Nicholas (2015). "Megalamphodus Eigenmann, 1915". WoRMS. World Register of Marine Species.
  7. 1 2 3 4 5 6 Lanés, Luis Esteban Krause; Bertaco, Vinicius; Volcan, Matheus (1 May 2023). "Discovery of Ectrepopterus uruguayensis (Fowler 1943) (Teleostei, Characiformes, Characidae) in the Brazilian Pampa". Instituto de Ecologia y Ciencias Ambientales. 18 (1). doi: 10.54451/PanamJAS.18.1.35 .
  8. ↑ Géry, J. (February 1972). "Corrected and supplemented descriptions of certain characoid fishes described by Henry W. Fowler, with revisions of several of their genera∗" (PDF). Studies on Neotropical Fauna. 7 (1): 14. doi:10.1080/01650527209360432 . Retrieved 13 October 2023.
  9. ↑ Scharpf, Christopher; Lazara, Kenneth J. (7 March 2024). "Family CHARACIDAE: Subfamily STETHAPRIONINAE Eigenmann 1907 (American Tetras)". The ETYFish Project. Retrieved 19 March 2024.
  10. ↑ "Ectrepopterus uruguayensis (Fowler 1943)". Encyclopedia of Life . National Museum of Natural History . Retrieved 12 October 2023.
  11. 1 2 Froese, Rainer; Pauly, Daniel (eds.) (2023). "Ectrepopterus uruguayensis" in FishBase . October 2023 version.
  12. 1 2 3 "Ectrepopterus uruguayensis Fowler 1943". treatment.plazi.org. Plazi TreatmentBank. Retrieved 13 October 2023.
  13. 1 2 3 Malabarba, Luiz R.; Bertaco, Vinicius A.; Carvalho, Fernando R.; Litz, Thomas O. "Ectrepopterus uruguayensis Fowler 1943". zenodo.org. Zenodo. Retrieved 13 October 2023.
  14. 1 2 3 4 Miquelarena, Amalia M.; Carvalho, Fernando R. (1 October 2013). "Actinopterygii, Characiformes, Characidae: Ectrepopterus uruguayensis (Fowler, 1943): new record for Argentina". Check List. 9 (5): 1043. doi: 10.15560/9.5.1043 . hdl: 11336/23365 .
  15. ↑ Angelini, Ronaldo; Aloísio, Gustavo Ribeiro; Carvalho, Adriana Rosa (2010). "Mixed food web control and stability in a Cerrado river (Brazil)" (PDF). Pan-American Journal of Aquatic Sciences. 5 (3): 421–431. Retrieved 12 October 2023.
  16. ↑ Paullier D´acosta, Sofia (2017). Diversidad de peces de la cuenca del Río Queguay (PDF) (Bachelor's thesis). Facultad de Ciencias, Universidad de la República. Retrieved 12 October 2023.
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