Iguanodectes adujai

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Iguanodectes adujai
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Characiformes
Family: Iguanodectidae
Genus: Iguanodectes
Species:
I. adujai
Binomial name
Iguanodectes adujai
Géry, 1970

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.

Contents

Though rare, it is seen in the aquarium trade, and is sometimes captured from the wild for collection or sale. I. adujai is sometimes sold in the same stock as congener I. geisleri, due to a markedly similar appearance.

Description

Iguanodectes adujai is a small tetra with a slender build, reaching a maximum of 6.2 cm (2.4 in) standard length (SL). [1] The general body shape has been described as similar to a smelt or minnow, something the genus Iguanodectes shares with sister genus Piabucus . [2] [3] [4] I. adujai specifically has pale-silver scales, a yellowish underside, and a red lateral stripe that ends in a blotch of pigmentation at the caudal fin. [5]

The lateral stripe can be used to tell two similar-looking species, Iguanodectes adujai and Iguanodectes geisleri , apart. In geisleri, the lateral stripe is three colors (red, yellow, and black, top-to-bottom), whereas in adujai it is only two (red and yellow). [6] Other identifying characteristics of I. adujai include the anal-fin origin lining up with the dorsal-fin origin (versus being located posterior to the dorsal-fin origin in I. geisleri) and 28-34 anal-fin rays (versus 20-25). [7]

Taxonomy

There are a total of 8 accepted species in the genus Iguanodectes. [8] I. adujai is a fairly recent addition in comparison with other members, the earliest of which ( Iguanodectes spilurus ) was named in 1864, though considered a member of related genus Piabucus at the time. The latest additions were all named in 1993. [9] I. adujai has no known scientific synonyms, having retained its original name since discovery. [10]

In terms of a common name, I. adujai is sometimes sold under the name "rust-stripe tetra" or "red line lizard tetra". [11] It should not be confused with congener I. geisleri, which is somewhat more common and is sold under the same name. [6] I. adujai has also been sold as the "rainbow lizard tetra" or the "slender tetra". [12] [13] The variety in nomenclature indicates weak consensus on how to refer to the species.

Most members of Iguanodectes are referred to as "piaba" in colloquial Brazilian settings. [4] [14]

Etymology

The specific name "adujai" originates from the igarapé Adujá, which is the type locality of I. adujai. "Iguanodectes" comes from "iguana", the lizard, and "dectes", meaning "bite" or "tooth"; though it was not made clear in the original text, it is assumed that this is in reference to the "lizard-like" dentition. [15]

Distribution and habitat

Iguanodectes adujai is known from Brazil, Venezuela, and Colombia. [16] Its type locality speaks to a preference for blackwater habitats, which are characterized by plentiful riparian vegetation and a substrate largely composed of leaf litter. [7] Specifically, it was first located in the igarapé Aduja, [15] which is a tributary of the Rio Itu, located in the middle Rio Negro basin. [17]

The Rio Negro basin is well-known for its floodplains, including an area in which the Itu is located, [18] and associated flooding cycles may have an influence on I. adujai's diet and behavior. The stretch of wetlands therein is inundated with blackwater rivers. [19] Within the Itu specifically, iron deposits are not uncommon. [20] The relevant riparian vegetation largely consists of sedges and palm trees. [21]

Diet and ecology

Iguanodectes adujai is an omnivorous species, though many Iguanodectes are largely herbivores. [4] It seems to be a fairly opportunistic feeder, including crustaceans, insects, algae, fallen fruit, and leaf litter in its diet. [22] Living in a floodplain means that its food sources fluctuate with the seasons. Little else is known of its interaction with its environment and the food web in its native range.

Conservation status

Iguanodectes adujai has not been evaluated by the IUCN, and is thus lacking in species-specific population evaluation. [23] Nonetheless, freshwater aquatic habitats - especially wetlands - in South America are frequently under pressure from various ongoing anthropogenic hazards, including illegal mining and infrastructure development. [24]

The wetlands of South America are known for their biodiversity, but also for their fragility. As such, conservation efforts are often undertaken to protect them, which offers wetland-dwelling species like I. adujai continued stability. [19] [25] Still, there are some legal and social complications surrounding protected sites therein, which may interfere with their role as sanctuaries for endemic species. [24]

Presence and behavior in aquaria

Iguanodectes adujai is exported from its native habitat to various locations, including Germany and Poland, on an uncommon basis. [22] [26] Aquarists describe a largely calm disposition, though males may get combative amongst themselves to establish a hierarchy. [5] It is reportedly sensitive to poor water conditions. [22]

Iguanodectes adujai and Iguanodectes geisleri are sometimes sold in the same stock and labeled as the same species because they may be difficult for the layperson to tell apart. [7]

Related Research Articles

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

The rummy-nose tetra is a species of tropical freshwater characin fish originating in South America, popular among fishkeepers as a tropical aquarium fish. One of many small tetras belonging to the same genus, it is on average 5 cm (2 in) long when fully grown. The fish is one of several very similar species including Petitella bleheri, and Petitella georgiae, and it is possible that more recently collected specimens available in the aquarium trade are members of one or other of these similar species. The common name applied to most of these fishes is "rummy-nose tetra", though other common names are in circulation.

<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.

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

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 disruptus is a small freshwater fish of the family Iguanodectidae. It is only found in the Rio Negro in South America. Like the rest of the genus Bryconops, B. disruptus is silvery in color, with a relatively deep chest and a notable set of teeth. The specific epithet "disruptus" refers to the incomplete lateral line.

<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.

<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 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.

<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 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.

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.

Piabucus caudomaculatus is a small freshwater fish inhabiting the rivers of South America. It was the first member of the family Iguanodectidae to be reported from Bolivia, and it remains endemic to the region, found solely in the Mamoré river basin. It displays a preference for slow-moving waterways and has a largely insectivorous diet.

<i>Piabucus melanostoma</i> Species of fish

Piabucus melanostoma, sometimes called the chin tetra, is a small species of freshwater fish from the rivers of South America. It is the second-largest species of the genus, but still only reaches about 12 cm (4 in) long. Occasionally found in captivity, it has an appealing iridescent-silver coloration. It is amongst the largest of fish still considered "tetras" in the aquarium hobby.

References

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