Gymnotus

Gymnotus
Gymnotus sp.
Systematics
Cohort : Otomorpha Sub-cohort : Ostariophysi Order : New World Knifefish (Gymnotiformes) Family : Knife eels (Gymnotidae) Subfamily : Gymnotinae Genre : Gymnotus
Scientific name of the  subfamily
Gymnotinae
Ellis , 1913
Scientific name of the  genus
Gymnotus
Linnaeus , 1758

Gymnotus is a genus from the family of the knife eels (Gymnotidae) in the order of the New World knife fish (Gymnotiformes). The genus has a large distribution area in Central and South America and occurs from the Río Motagua in Guatemala to the Rio Salado in Argentina. Depending on their size, the fish feed on small or larger invertebrates or on fish.

features

Gymnotus species reach lengths of 15 cm ( Gymnotus coropinae ) to one meter ( Gymnotus inaequilabiatus ) and have an elongated, laterally slightly flattened body with a long anal fin. The maximum body width is on average 60% of the maximum body height. The head makes up 7.2 to 15% of the total length. The small eyes lie below a horizontal line starting from the mouth. The front nostrils are smaller than the eyes. The upper mouth is medium to large in size and extends to the rear nostrils or further. It can reach a length of 24 to 42% of the head length and a width of 27 to 58% of the head width. The lower jaw is longer than the upper jaw. The premaxillary has 5 to 15 teeth arranged in two rows. In the lower jaw there are 5 to 16 teeth arranged in a row. They are conical, some can also be arrowhead shaped. The fleshy chin is rounded when viewed from above and from the side. The upper edge of the gill cover is convex to concave, the rear edge of the gill cover is smooth. The basibranchial (bones at the base of the branchial arch) are not ossified. The anal fin extends over 62 to 92% of the total length. It is supported by 130 to 390 fin rays. The pectoral fins vary in size and are supported by 9 to 22 fin rays. The sideline is complete and has 2 to 55 branches in the belly direction. Dorsal lateral branching is absent in adult specimens. Above the sideline there are 4 to 13 rows of scales, below there are 4 to 16. All scales are round or oval. Gymnotus species have a single electrical organ that is located in the abdominal region, extends over a large section of the total length of the fish and is used for orientation.

Gymnotus differs from the second genus of knife eels, the well-known electric eels ( Electrophorus ), among other things in its smaller size, the scaling (electric eels are not scaly) and the shorter anal fin. The latter extends to the tip of the tail in electric eels, and ends earlier in Gymnotus .

Subgenera and species

Within the genus there are seven sub-genera, 44 valid species and two previously undescribed species. The subgenera separated from one another 5 to 35 million years ago.

• Subgenus Gymnotus Craig et al., 2019 .
  • Gymnotus arapaima Albert & Crampton, 2001 .
  • Gymnotus ardilai Maldonado-Ocampo & Albert, 2004 .
  • Gymnotus bahianus Campos-da-Paz & Costa, 1996 .
  • Gymnotus carapo Linnaeus , 1758 .
  • Gymnotus capanema Milhomem, Crampton, Pierczeka, Shetka, Silva & Nagamachi, 2012 .
  • Gymnotus chaviro Maxime & Albert, 2009 .
  • Gymnotus chimarrao Cognato, Richer-de-Forges, Albert & Crampton, 2008 .
  • Gymnotus choco Albert, Crampton & Maldonado, 2003 .
  • Gymnotus cuia Craig et al., 2018 .
  • Gymnotus curupira Crampton, Thorsen & Albert, 2005 .
  • Gymnotus darwini Campos-da-Paz & Santana, 2019 .
  • Gymnotus diamantinensis Campos-da-Paz, 2002 .
  • Gymnotus eyra Craig et al., 2018 .
  • Gymnotus interruptus Rangel-Pereira, 2012 .
  • Gymnotus mamiraua Albert & Crampton, 2001 .
  • Gymnotus obscurus Crampton, Thorsen & Albert, 2005 .
  • Gymnotus omarorum Richer-de-Forges, Crampton & Albert, 2009
  • Gymnotus pantanal Fernandes, Albert, Daniel-Silva, Lopes, Crampton & Almeida-Toledo, 2005 .
  • Gymnotus riberalta Craig et al., 2018 .
  • Gymnotus sylvius Albert & Fernandes-Matioli, 1999 .
  • Gymnotus ucamara Crampton, Lovejoy & Albert, 2003 .
  • Gymnotus varzea Crampton, Thorsen & Albert, 2005 .
• Subgenus Lamontianus Craig et al., 2019 .
  • Gymnotus anguillaris Hoedeman, 1962 .
  • Gymnotus n. Sp. 'ARAP'
  • Gymnotus n. Sp. 'ARIP'
  • Gymnotus cataniapo Mago-Leccia, 1994 .
  • Gymnotus pedanopterus Mago-Leccia, 1994 .
  • Gymnotus tiquie Maxime, Lima & Albert, 2011 .
• Subgenus Pantherus Craig et al., 2019 .
  • Gymnotus capitimaculatus Rangel-Pereira, 2014 .
  • Gymnotus pantherinus ( Steindachner , 1908) .
  • Gymnotus refugio Giora & Malabarba, 2016 .
• Subgenus Tigre Craig et al., 2019 .
  • Gymnotus esmeraldas Albert & Crampton, 2003 .
  • Gymnotus henni Albert, Crampton & Maldonado, 2003 .
  • Gymnotus inaequilabiatus ( Valenciennes , 1842) .
  • Gymnotus paraguensis Albert & Crampton, 2003 .
  • Gymnotus tigre Albert & Crampton, 2003 .
• Subgenus Tigrinus Craig et al., 2019 .
  • Gymnotus coatesi La Monte, 1935 .
  • Gymnotus coropinae Hoedeman, 1962 .
  • Gymnotus javari Albert, Crampton & Hagedorn, 2003 .
  • Gymnotus jonasi Albert & Crampton, 2001 .
  • Gymnotus melanopleura Albert & Crampton, 2001 .
  • Gymnotus onca Albert & Crampton, 2001 .
  • Gymnotus stenoleucus Mago-Leccia, 1994 .
• Subgenus Tijax Craig et al., 2019 .
  • Gymnotus cylindricus La Monte, 1935 .
  • Gymnotus maculosus Albert & Miller, 1995 .
  • Gymnotus panamensis Albert & Crampton, 2003 .

supporting documents

1. ↑ ^{a b c d} Craig, JM, Kim, LY, Tagliacollo, VA & Albert, JS (2019): Phylogenetic revision of Gymnotidae (Teleostei: Gymnotiformes), with descriptions of six subgenera. PLoS ONE, 14 (11): e0224599. November, 2019, doi: 10.1371 / journal.pone.0224599
2. ↑ Campos-da-Paz, R. & Santana, CD (2019): A New Species of the Electric Knifefish Gymnotus Linnaeus (Gymnotiformes: Gymnotidae) from Northeastern Brazil. Copeia, 107 (1): 144-151. doi: 10.1643 / CI-18-141

Web links

• Gymnotus on Fishbase.org (English)