Sternarchogiton

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Sternarchogiton
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Sternarchogiton

Sternarchogiton is a genus of weakly electric knifefish in the family Apteronotidae, with four known species, [1] all living in the main channel of large rivers in the Amazon and Orinoco basins in South America. [2]

They have a blunt snout and depending on the exact species reach up to 20–40 cm (8–16 in) in total length. [2] The adult males of S. nattereri have teeth on the outside of the jaw, believed to be used in fights with other males, and it was formerly placed in its own genus because of this unique feature. [2] [3] Sternarchogiton are distinguished from other apteronotid genera by details of the skull and the broad descending blades of the pterygiophores in the anal fin. They are related to the genera Adontosternarchus and Porotergus . [4]

Species

There are four recognized species: [1]

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<i>Pygocentrus</i> Genus of fishes

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Sternarchogiton nattereri is a species of weakly electric knifefish in the family Apteronotidae. It is native to the Amazon River system and feeds on sponges. Unlike other members of the genus Sternarchogiton, there is pronounced sexual dimorphism in S. nattereri, with reproductively mature males developing strong external teeth on tips of their jaws. These males are so different from the females and juveniles that they were thought to be a different genus and species, the "tooth-lip knifefish" Oedemognathus exodon, for over 40 years.

Sternarchogiton porcinum is a species of weakly electric knifefish in the family Apteronotidae. It is native to deep river channels in the Río Huallaga, Río Napo, and Río Amazonas in Peru, and in the Río Orinoco in Venezuela. Many specimens once identified as S. porcinum from the Brazilian Amazon Basin and the Venezuelan Orinoco are now known to be a different species, S. preto.

<i>Apteronotus</i> Genus of fishes

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<i>Pariosternarchus</i> Genus of fishes

Pariosternarchus amazonensis is a little-known species of weakly electric knifefish in the family Apteronotidae, and the only member of its genus. It is found in the main channel of the Amazon River in Brazil and Peru, likely near the bottom in deep, fast-moving water. This species is characterized by a wide head with a flat bottom, and very large sensory canals along the lower jaw. Like several other knifefishes found in deep river channels, it has reduced eyes, scales, and body pigmentation.

<i>Adontosternarchus</i> Genus of fishes

Adontosternarchus is a genus of ghost knifefishes found in Amazon and Orinoco river basins in tropical South America. They have blunt snouts, a dark-spotted or -mottled pattern on a pale background and reach up to 18.5–32.2 cm (7.3–12.7 in) in total length. They feed on zooplankton and can be found quite deep, with A. devenanzii recorded down to 84 m (276 ft).

Compsaraia is a genus of ghost knifefishes found in tropical South America. There are currently three described species in this genus. They are found deep in large rivers in the Amazon and Orinoco basins, and have small eyes and little pigment.

Platyurosternarchus is a genus of ghost knifefishes found in the Amazon, Orinoco and Essequibo river basins in tropical South America. They are medium-sized knifefish that reach up to 41.5 cm (16.3 in) in total length and have a relatively long, downwards-pointed tubular snout. They are typically found in streams or near the shore of rivers, often among submerged tree trunks and branches over a leaf-covered bottom where they find their invertebrate prey.

Porotergus is a genus of ghost knifefishes found in the Amazon and Essequibo basins in tropical South America. They are found over sandy bottoms in shallow or deep rivers. They feed on small aquatic insect larvae. They have a stubby snout and are fairly small knifefish, with the largest species reaching up to 27 cm (11 in) in total length.

Sternarchella, the bulldog knifefish, is a genus of ghost knifefishes found at depths of 2–50 m (7–164 ft) in the main channel of large rivers in South America. Most are from the Amazon basin, but S. orthos is found both in the Amazon and Orinoco, S. orinoco is restricted to the Orinoco and S. curvioperculata restricted to the upper Paraná basin. They are often common in their habitat.

Brachyhypopomus is a genus of fish in the family Hypopomidae native primarily to tropical and subtropical South America, although a single species, B. occidentalis, also occurs in Panama and Costa Rica. They are found in a wide range of static or slow-flowing freshwater habitats such as edges of rivers, streams, floodplains and swamps, but they are absent from deep river channels. There are both species in well-oxygenated waters and poorly oxygenated waters; those in the latter have adaptions that allow them to survive this like larger gills or the capability of gulping up mouthfuls of air from the water surface. Brachyhypopomus feed during the night on small invertebrates. Shout out to William Clifford for finding the fish B).

Hypopygus is a genus of South American gymnotiform knifefishes native to the Amazon, Orinoco and upper Paraguay basins, as well as rivers in the Guianas. They are often common, and found near submerged roots, aquatic vegetation and leaf-litter in streams, edges of rivers and floodplains. They are regularly found among vegetation in floating meadows, a habitat that often contains little oxygen, but they are well-adapted to this.

Microsternarchus is a genus of bluntnose knifefish that is found in creeks and streams, often in areas with submerged vegetation, roots and leaf litter, in the Amazon, Orinoco, Essequibo–Rupununi and Río de la Plata basins in South America. The two recognized species are both small knifefish, with the largest being M. bilineatus at up to 12 cm (4.7 in) in total length. The other is M. brevis, which at up to only 5.3 cm (2.1 in) is the world's smallest knifefish. Microsternarchus are very similar to Brachyhypopomus.

<i>Steatogenys</i> Genus of fishes

Steatogenys is a genus of gymnotiform knifefishes found in the Amazon, Orinoco and Essequibo river basins in tropical South America. The widespread and common S. elegans is found in a wide range of habitats, from the shallow essentially static waters such as floodplain lakes to fast-flowing rivers as deep as 50 m (160 ft). The two remaining species are less common and widespread, with A. duidae found mainly in small streams running through terra firme forests and S. ocellatus among submerged roots and branches in static or slow-flowing blackwater habitats. All three are regularly found among vegetation in floating meadows, a habitat that often contains little oxygen, but they are well-adapted to this.

Rhabdolichops is a genus of glass knifefishes found in Amazon, Orinoco and Maroni basins in tropical South America. They live near the bottom in main river channels, floodplains and lagoons, and are typically found in relatively deep waters.

References

  1. 1 2 Froese, Rainer and Pauly, Daniel, eds. (2017). Species of Sternarchogiton in FishBase . October 2017 version.
  2. 1 2 3 van der Sleen, P.; J.S. Albert, eds. (2017). Field Guide to the Fishes of the Amazon, Orinoco, and Guianas. Princeton University Press. p. 329. ISBN   978-0691170749.
  3. Froese, Rainer, and Daniel Pauly, eds. (2017). "Apteronotidae" in FishBase . October 2017 version.
  4. de Santana, C.D.; Crampton, William G. R. (2007). "Revision of The Deep-channel Electric Fish Genus Sternarchogiton (Gymnotiformes: Apteronotidae)". Copeia. 2007 (2): 387–402. doi:10.1643/0045-8511(2007)7[387:ROTDEF]2.0.CO;2. S2CID   86035117.