Iguanodectes spilurus

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Iguanodectes spilurus
Not evaluated (IUCN 3.1)
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Class:
Actinopterygii
Order:
Characiformes
Family:
Iguanodectidae
Subfamily:
Iguanodectinae
Genus:
Iguanodectes
Species:
Iguanodectes spilurus
Binomial name
Iguanodectes spilurus
Günther, 1864

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 (and is thus a differentiating feature).

Contents

For a time, researchers had uncertainties regarding the taxonomic status of I. spilurus. It was originally named as a member of sister genus Piabucus , and then was described with the name I. tenuis. However, its modern placement as a member of Iguanodectes with specific name spilurus is generally accepted by the scientific community.

Description

Iguanodectes spilurus is a small fish, reaching a maximum of 10.2 cm (4.0 in) in standard length (SL). [1] Based on hobbyist reports, captive specimens, or specimens for sale in the trade, more often reach a maximum of roughly 5 cm (2 in). [2] [3] Its body is silvery in color, its fins are largely translucent, and it lacks a red lateral stripe (which is seen in multiple other members of the genus). [4] Instead, its lateral-line scales are reflective green in color, which is the origin of one of its common names - "green-line lizard tetra". The base of its caudal fin sports a distinct black spot. [5]

Iguanodectes is generally a complex genus in terms of morphology, both interspecies and intraspecies, and I. spilurus is an example of this. Ichthyologist Jacques Gery considered it a polymorphic species (i.e. a species that has multiple documented different appearances or forms), though acknowledged uncertainty regarding the causes and mechanisms therein. [6] Several comparative factors can help differentiate it from similar congeners, including its number of lateral-line scales (60-64) and predorsal scales (24). [7]

All members of Iguanodectes are narrow-bodied and shallow-chested, lacking the deep chest seen in sister genus Piabucus. The pectoral fins are also shorter in Iguanodectes. [8]

Sexual dimorphism

The sexual dimorphism of I. spilurus is minor, but present. Males have small hooks or protrusions on the first few rays of the anal fin during mating season, [4] which is not uncommon in the family Iguanodectidae as a whole. It is more prominent in related genus Bryconops , from the same family. [9]

Taxonomy

Iguanodectes spilurus was originally described as Piabuca spilurus by German-British zoologist Albert Günther in 1864. [10] American ichthyologist Edward Drinker Cope later described it as Iguanodectes tenuis in 1872, under the impression that he was studying a separate species entirely; [11] this was possibly due to the varying coloration of I. spilurus. [6] I. tenius and P. spilurus were synonymized by American ichthyologist James Erwin Böhlke in 1954, with input from Ethelwynn Trewavas, a fellow ichthyologist. Its generic placement within Iguanodectes, a novel genus upon nomination of I. tenuis, was deemed correct based on morphological features, but spilurus became the accepted specific epithet, as it was established prior. [12]

Böhlke also considered Iguanodectes rachovii synonymous with I. spilurus, [12] but this is rejected by modern ichthyologists. I. rachovii is considered its own species. [13]

Etymology

The specific epithet "spilurus" has Greek roots. "Spilos" means "spot" (compare " Spilogale ", the genus of spotted skunks), and "ouros" means "tail" (compare "Ouroboros", the serpent eating its own tail). This is in reference to the distinct spot of pigment on the caudal fin that occupies the junction between lobes. The generic name "Iguanodectes", meanwhile, lacks a clear given meaning in its nominal text; modern etymologists believe that it can be traced to "iguana", the lizard, and "dectes", meaning "tooth" or "bite". [5]

Iguanodectes spilurus sometimes goes by the common name "green-line lizard tetra", based on the way its lateral-line scales reflect green light. [4] Suppliers of ornamental fish can be found selling it under this name. [14] [15]

Distribution and habitat

Iguanodectes spilurus is known from the Amazon, Essequibo, Orinoco, and Tocantins river basins; thus, it is the most widespread member of Iguanodectes. [4] It demonstrates a preference for rocky substrate and flowing water, though it is found in both blackwater (slow-moving) and clearwater habitats. [1] [16] [17]

Diet and ecology

Iguanodectes spilurus is omnivorous, and is a visual animal, using sight to pursue prey (as opposed to a mechanism like sensory barbels). [16] Along with invertebrates, it also eats algae, leaf litter, and detritus. [17] It seems to be easygoing by nature, living in sympatry with various other fish species within its native range (including congeners I. geisleri and I. polylepis ). [6]

Iguanodectes spilurus is subject to infection by parasitic nematode larvae of several genera that colonize various internal organs and bodily systems. The liver appears to be the most susceptible to damage from parasitic activity. [18]

Presence and behavior in aquaria

Aquarists report that I. spilurus is a peaceful species that adapts well to a tank environment. [19] It prefers to be kept in schools of at least 5 congeners, and an optimal aquarium setup for I. spilurus reportedly includes ample swimming room near the surface of the water. [2] Iguanodectes as a genus is not a common sight in the aquarium industry, but is sometimes exported from its native range to countries including Germany and Poland. [20] [21]

Conservation status

Iguanodectes spilurus has not been evaluated by the IUCN. [1] However, its range spans several river basins and countries therein, which provides a stable basis for its population. [4] Its wide range also indicates an ability to adapt to changes in its environment (at least to an extent). Therefore, it is unlikely to face immediate threats of endangerment or extinction.

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 (5.0 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.

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

Bryconops alburnoides is a small freshwater fish, approximately 6 inches long at its largest, that lives in the rivers of South America. It has a slender body, with a yellowish dorsal fin and yellow-tinged back scales that fade into silver on its belly. It is largely an insectivore that picks land-dwelling insects from the riverbanks, though it eats much more whenever rain washes prey into the water.

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

The tailspot tetra is a freshwater fish that lives in the coastal river regions of upper South America. Both its common and scientific names reference the distinct spot of color present on the tail fin, which is one of its defining characteristics. It is a small fish, reaching 4.8 in at its longest. Despite its small size, it is an active swimmer, with a preference for fast-flowing waters.

Bryconops collettei is a small freshwater fish from the rivers of South America. It is mostly silvery, with notable green iridescence on its sides, and a diffuse ocellus (eyespot) on the upper lobe of the caudal fin. Before its distinction as a separate species, specimens of B. collettei were misidentified as specimens of Bryconops caudomaculatus due to several morphological similarities, including a caudal ocellus and generally similar fin coloration.

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 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 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.

Bryconops hexalepis is a small iguanodectid fish from the rivers of Brazil. It is solely found in the drainage of the Rio Tocantins. Rather elongate and quite slender, it is considered one of the smaller species of its genus, with tall scales and large eyes.

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 rachovii is a species of freshwater fish that inhabits the rivers of the Amazon basin. It largely consumes insects, though it will eat plants if given the opportunity, and has a peaceful disposition, able to live alongside various other species. It is often found in groups of 3 to 30 specimens, lingering at the edges of streams near the surface of the water.

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.

References

  1. 1 2 3 Froese, Rainer; Pauly, Daniel (eds.) (2022). "Iguanodectes spilurus" in FishBase . December 2022 version.
  2. 1 2 Chandler, Patrice. "Slender Tetra, Iguanodectes Spilurus – Care & Stats". badmanstropicalfish.com. Badman's Tropical Fish. Retrieved 29 December 2022.
  3. ↑ "Iguanodectes spilurus - Slender Tetra". www.wetspottropicalfish.com. Wet Spot Tropical Fish. Retrieved 29 December 2022.
  4. 1 2 3 4 5 "Iguanodectes spilurus - Green Line Lizard Tetra". www.seriouslyfish.com. Seriously Fish. Retrieved 29 December 2022.
  5. 1 2 Scharpf, Christopher; Lazara, Kenneth J. (15 September 2020). "Order CHARACIFORMES: Families IGUANODECTIDAE, TRIPORTHEIDAE, BRYCONIDAE, CHALCEIDAE and GASTEROPELECIDAE". The ETYFish Project. Retrieved 29 December 2022.
  6. 1 2 3 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.
  7. ↑ da Silva, Luís R. R. (July 2020). "Delimitação Molecular de Espécies da Família Iguanodectidae (Teleostei, Characiformes)" (PDF). Retrieved 29 December 2022.{{cite journal}}: Cite journal requires |journal= (help)
  8. ↑ 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. ISBN   85-7430-361-5. OCLC   54496178.{{cite book}}: CS1 maint: others (link)
  9. ↑ "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
  10. ↑ "Iguanodectes spilurus (Günther, 1864)". Global Biodiversity Information Facility. Retrieved 28 December 2022.
  11. ↑ Cope, E. D. (1872). On the fishes of the Ambyiacu River. Philadelphia: Academy of Natural Sciences. p. 260. doi:10.5962/bhl.title.11798.
  12. 1 2 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.
  13. ↑ Bailly, Nicolas. "Iguanodectes Cope, 1872". www.marinespecies.org. World Register of Marine Species. Retrieved 29 December 2022.
  14. ↑ "GREEN LINE LIZARD TETRA (Iguanodectes spilurus)". aquaristsacrosscanada.com. Aquarists Across Canada. Retrieved 29 December 2022.
  15. ↑ "Green Line Lizard Tetra (Iguanodectes spilurus)". dansfish.com. Dan's Fish. Retrieved 29 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. 1 2 "Iguanodectes spilurus". www.pecesdebolivia.com. Bolivian Fish Atlas: Bolivian Fauna Collection (National Museum of Natural History – Institute of Ecology). Retrieved 29 December 2022.
  18. ↑ Fujimoto, Rodrigo Yudi; Anjos, Ellem Cristina Silva dos; Ramos, Fabrício Menezes; Martins, Maurício Laterça (December 2013). "Seasonality of nematode larvae in Iguanodectes spilurus (Characidae) an ornamental fish from northeastern Para, Brazil". Acta Amazonica. 43 (4): 511–516. doi: 10.1590/S0044-59672013000400013 .
  19. ↑ "Iguanodectes spilurus". akwa-mania.mud.pl. AKWA-MANIA. Retrieved 29 December 2022.
  20. ↑ Schäfer, Frank. "Iguanodectes geisleri". aquariumglaser.de. Aquarium Glaser GmbH. Retrieved 2 December 2022.
  21. ↑ "Iguanodectes spilurus". akwarium.info.pl (in Polish). Retrieved 29 December 2022.
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