Iguanodectes variatus

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Iguanodectes variatus
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Characiformes
Family: Iguanodectidae
Genus: Iguanodectes
Species:
I. variatus
Binomial name
Iguanodectes variatus
Géry, 1993

Iguanodectes variatus is a small freshwater fish, described from the rivers of South America in 1993. It has a minor presence in the aquarium trade, but lacks the popularity that would make excessive wild capture a legitimate threat. That being said, the threats facing South American aquatic environments are of ongoing concern for the associated biodiversity. Still, I. variatus has been recorded from various rivers and has shown general adaptability to its environment, which speaks to a high survivability.

Contents

Description

Iguanodectes variatus reaches a maximum of 10.3 cm (4.1 in) standard length (SL). [1] As with the rest of its genus, its base scale color ranges from silver to silvery-yellow (more often the former), but it has characteristic mottling on its sides in light-brown. The top of the snout is also colored brownish, which can help distinguish it from similar-looking congeners, [2] though the light-brown mottling is unique to I. variatus within Iguanodectes regardless. [3] It has a lateral line in reflective green, somewhat reminiscent of congener I. spilurus , and it has a dark stripe on its caudal fin that strictly occupies the middle portion therein. [2]

Species of Iguanodectes are generally narrow-bodied and slender, drawing comparisons to smelt or minnows. [4] [5] They usually bear some resemblance to sister genus Piabucus , but members of Piabucus have deeper chests and longer pectoral fins. [6]

Sexual dimorphism

The sexual dimorphism, or lack thereof, within I. variatus specifically is unknown. However, male specimens of several congeners demonstrate small hooks or spines on the first few rays of the anal fin during mating season, such as I. geisleri [7] and I. purusii , [2] which suggests the possibility of similar features in I. variatus. This particular dimorphism is not uncommon within the family Iguanodectidae as a whole, and is slightly more prevalent in familial genus Bryconops . [8]

Taxonomy

Named in 1993, I. variatus is one of three species described by French ichthyologist Jacques Géry in its nominal paper; the other two are congeners Iguanodectes polylepis and Iguanodectes gracilis . [2] These three species are the most recent additions to the genus, out of eight species total. [9] I. variatus has retained its original name, and has no known synonyms. [10]

DNA barcoding has revealed some genetic similarity to related species Bryconops melanurus , though not enough for it to be of taxonomic note. [11]

Etymology

The specific name "variatus" means "spotting", as in "variation of color", which is in reference to the mottling on the sides of adults. The generic name "Iguanodectes", while without a specified origin in its nominal text, is likely from "iguana", the lizard, and "dectes", meaning "bite" or "tooth". [3]

Distribution and habitat

Iguanodectes variatus is found throughout the basins of the Branco, Guaporé, Trombetas, and Urubu rivers, as well as the Madeira. [12] This restricts its range to Brazil. It was originally described from a stream called the Igarapé Jatuarana, in the Guaporé watershed. [6] Furthermore, it has most often been sighted in the upper portions of the water column, inhabiting areas of somewhat stronger current. [13]

Diet and ecology

Though information regarding the diet of I. variatus is somewhat sparse, aquarists report omnivorous tendencies. [14] The general tooth structure suggests food intake similar to the rest of the genus, including filamentous algae and aquatic invertebrates. [2] Other reports of Iguanodectes as a whole describe a more herbivorous disposition. [8]

It is reportedly a social fish that prefers to live in schools, which is in keeping with habits seen in the rest of the genus. [15] The specific extent of sympatry with other species is unknown, but it is known to be widespread and adaptable in nature, and is thus unlikely to be particularly territorial. [16]

Presence and behavior in aquaria

The genus Iguanodectes as a whole is not often exported for trade from within its native range. Several species are more popular than I. variatus, including I. geisleri, I. adujai , and I. spilurus. [7] However, I. variatus is at least of minor note in aquaria, seen in reports from hobbyists in European locations such as Poland. [14] [15]

Conservation status

Iguanodectes variatus has not been evaluated by the IUCN. [1] It is known to live in areas affected by the pesticide Chlorpyrifos, though knowledge of its response to contamination has not been published. [17] Otherwise, it is wide-ranging and adaptable, which means a stable population and a low likelihood of endangerment. [16]

Related Research Articles

<i>Bryconops</i> Genus of fishes

Bryconops is a genus of freshwater fish in the family Iguanodectidae from South America. It consists of small fish, all under half-a-foot long, with slender bodies and silvery scales, though there is some mild color variation. Several species can be identified by way of a humeral patch, and others have a reddish ocellus, or eyespot, on one or both lobes of the dorsal fin.

<i>Iguanodectes</i> Genus of fishes

Iguanodectes is a genus of freshwater fish found in tropical South America, with eight currently described species. They are all small tetras, none longer than 5 inches, and often have attractive silvery or striped scales, which makes them a target for the ornamental fish industry. Alongside the genus Piabucus, it is in the subfamily Iguanodectinae, which in turn is in the family Iguanodectidae. The genus Bryconops, which is also in Iguanodectidae, makes up a sister clade to Iguanodectinae.

<i>Piabucus</i> Genus of fishes

Piabucus is a genus of freshwater tetras in the family Iguanodectidae. All three species are found in South America, largely the Amazon and its major tributaries. None of them are longer than half a foot long, with the largest reaching a maximum size of 12.9 cm (5.1 in), and they are slender, with relatively deep chests and long pectoral fins. Their scales are pale or silvery, with lateral lines that stand out.

<span class="mw-page-title-main">Iguanodectidae</span> Family of fish

Iguanodectidae is a family of freshwater fish in the order Characiformes that lives in South America. It is home to the subfamily Iguanodectinae and the monotypic Bryconops clade. Several species in the family, such as the green line lizard tetra, the tailspot tetra, and the orangefin tetra, are sometimes taken as aquarium fish.

<span class="mw-page-title-main">Iguanodectinae</span> Family of fish

Iguanodectinae is a subfamily of small freshwater fish in the family Iguanodectidae. They are most prominently found in the Amazon river basin and its major tributaries, but they are also known from the Tocantins, Orinoco, and Paraguay rivers. It has two genera, Piabucus and Iguanodectes. Some species in the subfamily are taken from the wild for aquariums, like the red- and green-line lizard tetras. There is minor, but ongoing, debate regarding its taxonomy.

Bryconops durbinae, sometimes listed under the name Bryconops durbini, is a small species of freshwater fish in the family Iguanodectidae. It is the smallest species of the genus Bryconops, and is endemic to the Tapajós river basin in Brazil.

<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.

Bryconops humeralis is a small freshwater fish distributed across northern South America. The name "humeralis" means "relating to the shoulder", in reference to the distinct humeral patches that the fish sports. It is slightly longer than average in terms of the genus Bryconops, though still firmly within the standard range, and is slightly more slender than is usual for its congeners.

Bryconops inpai is a small freshwater fish native to the rivers of South America. It only lives in two particular river systems - the Casiquiare and Negro - which means that its range is restricted to the northern half of the continent. It has indistinct humeral spots, and is bluish-silver in life, which is unusual for members of Bryconops; they are more often plain silver or greenish-silver.

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

Bryconops magoi is a small species of fish from South America. It is only found in Venezuela, along with sister species Bryconops collettei. Its tail-fin markings help to differentiate it from various congeners, as does its fairly restricted range. It is most closely related to B. collettei and Bryconops caudomaculatus, and it was once considered synonymous with the latter; specimens of B. magoi and B. collettei both were routinely misidentified as B. caudomaculatus before being given species distinction.

Bryconops munduruku is a small freshwater fish of the family Iguanodectidae that lives in the rivers of South America. Its adipose fin is black, with a clear base, and it has two humeral spots, which is a feature it shares with few congeners. Its fins are a variety of yellow, red, black, and clear, and mature males have hooks on select fin-rays.

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

Bryconops piracolina is a small fish that inhabits the waters of Brazil. It is slender and silvery in color, like many fish in Bryconops, but can be distinguished from other members by way of its dorsal fin, which has a black patch of color extending up from the fin-base; congeners usually have light pigment in the dorsal fin, or a brighter color.

Bryconops vibex is a small freshwater fish from the rivers of Venezuela, known solely from the Rio Cataniapo. The body is slender, though with an element of sturdiness, and it has one humeral spot by each pectoral fin. It bears visual similarities to several congeners, but can be differentiated by way of many factors.

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

Bryconops florenceae is a small freshwater fish that inhabits the rivers of South America. Comprehensive research is lacking due to B. florenceae being the most recently described of the genus, but researchers believe it to be a relatively widespread species. It is found throughout the Maroni, Mana, and Sinnamary river basins, which defines its range within Suriname and French Guiana.

Iguanodectes adujai is a species of freshwater fish that inhabits the rivers of South America. It largely prefers slow-moving blackwater habitats, though it has a slender body that suggests a further affinity for flowing water. It has a distinct lateral stripe in two horizontal sections, with bright-red at the top and yellow at the bottom.

<i>Iguanodectes geisleri</i> Species of fish

Iguanodectes geisleri, the red-line lizard tetra, is a species of freshwater fish from South America. It is a small species, largely herbivorous with some omnivorous traits, that prefers to live in schools and is partial to shallow waters, especially in blackwater habitats. Some aspects of its body plan are unique amongst its genus, including the position and length of the anal fin.

Iguanodectes gracilis is a small species of freshwater fish from South America. It is known solely from the Rio Negro river system, which restricts its range only to Brazil. The name "gracilis" is in reference to a slender body shape, alongside the diminutive nature of I. gracilis - it is the smallest member of the genus Iguanodectes.

Iguanodectes polylepis is a species of freshwater fish from the rivers of South America. Its range is restricted to Brazil, where it inhabits the Madeira and Purus river basins. It is one of the larger members of the genus, but remains generally small, only a little over a quarter-foot long.

Iguanodectes purusii is a small freshwater fish from the rivers of South America. It is largely herbivorous, and prefers to live in schools. The name "purusii" originates from the species' type locality, the Purus river basin of Brazil, with a range that also extends into Peru. Furthermore, it has been documented from the Amazon, Madeira, Guaporé, and Pastaza rivers, but specific study of its ecology is otherwise lacking.

Iguanodectes spilurus, the green-line lizard tetra, is a small characiform fish from the rivers of South America. It is not a well-studied species, but research is available, including data from hobbyists that keep it as an ornamental fish. It has a distinct lateral stripe of reflective-green scales, and lacks any red markings therein; red is common in congeners' lateral stripes.

References

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  2. 1 2 3 4 5 Géry, J. 1993. "Description de trois espèces nouvelles du genre Iguanodectes (Pisces, Characiformes, Characidae), avec quelques données récentes sur les autres espèces." Revue française d'Aquariologie Herpétologie 19(4): 97-106.
  3. 1 2 Scharpf, Christopher; Lazara, Kenneth J. (15 September 2020). "Order CHARACIFORMES: Families IGUANODECTIDAE, TRIPORTHEIDAE, BRYCONIDAE, CHALCEIDAE and GASTEROPELECIDAE". The ETYFish Project. Archived from the original on 6 November 2019. Retrieved 29 December 2022.
  4. Eigenmann, Carl H.; Meyers, George S. (1917–1929). The American Characidae. Cambridge. pp. 493–499. Retrieved 31 December 2022.
  5. Böhlke, James E. (1954-02-01). "XV.—Studies on fishes of the family Characidae.—No. 6. A synopsis of the Iguanodectinae". Annals and Magazine of Natural History. 7 (74): 97–104. doi:10.1080/00222935408651699. ISSN   0374-5481.
  6. 1 2 Check list of the freshwater fishes of South and Central America. Roberto E. Reis, Sven O. Kullander, Carl J. Ferraris, Pontifícia Universidade Católica do Rio Grande do Sul. Museu de Ciências e Tecnologia. Porto Alegre, Brasil: EDIPUCRS. 2003. pp. 172–173. ISBN   85-7430-361-5. OCLC   54496178.{{cite book}}: CS1 maint: others (link)
  7. 1 2 Schäfer, Frank (6 May 2013). "Iguanodectes geisleri". aquariumglaser.de. Aquarium Glaser GmbH. Retrieved 2 December 2022.
  8. 1 2 "THE FISH FAMILIES". Field Guide to the Fishes of the Amazon, Orinoco, and Guianas, edited by Peter van der Sleen and James S. Albert, Princeton: Princeton University Press, 2017, pp. 95-96. https://doi.org/10.1515/9781400888801-009
  9. Bailly, Nicolas. "Iguanodectes Cope, 1872". www.marinespecies.org. World Register of Marine Species. Retrieved 29 December 2022.
  10. "Iguanodectes variatus (Géry, 1993)". Global Biodiversity Information Facility. Retrieved 28 December 2022.
  11. Guimarães, Karen Larissa Auzier; de Sousa, Marcos Paulo Alho; Ribeiro, Frank Raynner Vasconcelos; Porto, Jorge Ivan Rebelo; Rodrigues, Luís Reginaldo Ribeiro (21 December 2018). "DNA barcoding of fish fauna from low order streams of Tapajós River basin". PLOS ONE. 13 (12): e0209430. Bibcode:2018PLoSO..1309430G. doi: 10.1371/journal.pone.0209430 . PMC   6303048 . PMID   30576366.
  12. "Iguanodectes variatus (Géry, 1993)". seriouslyfish.com. SeriouslyFish. Retrieved 1 January 2023.
  13. Fróis, Raul de Paula da Silva; Ribeiro, Bruno Oliveira; Zuanon, Jansen; Mortati, Amanda Frederico (2021). "Fish fauna of small-order streams of savannah and forest fragments landscape in the lower Tapajós River basin, Amazonia". Biota Neotropica. 21 (4). doi: 10.1590/1676-0611-BN-2020-1179 . S2CID   239721769 . Retrieved 1 January 2023.
  14. 1 2 "Iguanodectes variatus". akwa-mania.mud.pl. AKWA-MANIA. Retrieved 31 December 2022.
  15. 1 2 "Iguanodectes variatus". akwarium.info.pl (in Polish). Retrieved 30 December 2022.
  16. 1 2 Carvalho, Rodrigo Assis; Tejerina-Garro, Francisco Leonardo (June 2015). "The influence of environmental variables on the functional structure of headwater stream fish assemblages: a study of two tropical basins in Central Brazil". Neotropical Ichthyology. 13 (2): 349–360. doi: 10.1590/1982-0224-20130148 .
  17. dos Santos, Soraia B. (6 August 2019). "Evaluation of the Toxicity of the Pesticide Chlorpyrifos and its effect on the behavior of fish of the species Iguanodectes variatus (Géry, 1993)". Unpublished master defense. PPGBIO Graduate Program in Biosciences. Retrieved 1 January 2023.