''Apteronotus'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of weakly electric knifefish in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Apteronotidae The ghost knifefishes consist of the family Apteronotidae, which are ray-finned fishes in the order Gymnotiformes. These fish are native to Panama and South America. They inhabit a wide range of freshwater habitats, but more than half the specie ...

, distinguished by the presence of a tiny tail fin. This genus is restricted to tropical and subtropical

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

(

Amazon Amazon most often refers to: * Amazon River, in South America * Amazon rainforest, a rainforest covering most of the Amazon basin * Amazon (company), an American multinational technology company * Amazons, a tribe of female warriors in Greek myth ...

Orinoco The Orinoco () is one of the longest rivers in South America at . Its drainage basin, sometimes known as the Orinoquia, covers approximately 1 million km2, with 65% of it in Venezuela and 35% in Colombia. It is the List of rivers by discharge, f ...

Río de la Plata The Río de la Plata (; ), also called the River Plate or La Plata River in English, is the estuary formed by the confluence of the Uruguay River and the Paraná River at Punta Gorda, Colonia, Punta Gorda. It empties into the Atlantic Ocean and ...

and Magdalena basins, as well as rivers in western

Colombia Colombia, officially the Republic of Colombia, is a country primarily located in South America with Insular region of Colombia, insular regions in North America. The Colombian mainland is bordered by the Caribbean Sea to the north, Venezuel ...

and the

Guianas The Guianas, also spelled Guyanas or Guayanas, are a geographical region in north-eastern South America. Strictly, the term refers to the three Guianas: Guyana, Suriname, and French Guiana, formerly British Guiana, British, Surinam (Dutch colo ...

) and

Panama Panama, officially the Republic of Panama, is a country in Latin America at the southern end of Central America, bordering South America. It is bordered by Costa Rica to the west, Colombia to the southeast, the Caribbean Sea to the north, and ...

where found in a wide range of freshwater habitats. They feed on small animals. Depending on the exact species, they reach a total length of up to about . Although it has been claimed that ''A. magdalenensis'' is up to long, this is not supported by recent studies and likely the result of confusion with '' Sternopygus aequilabiatus''. Members of ''Apteronotus'' fall into three

species group In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each oth ...

s based on their

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines *Morphology (archaeology), study of the shapes or forms of artifacts *Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies, ...

: the ''A. albifrons'' group have a rounded snout and are black or dark brown with a contrasting light stripe on the top of the head, and bands on the tail and at its base, the ''A. leptorhynchus'' group have an elongate, slender snout (especially in males) and are brown with a light stripe along the head and back, and a band on the tail, and the ''A. bonapartii'' group have an elongate (males) or rounded (females) snout and are brown or gray (capable of some color change) with a light band on the tail. The last group is not closely related to the first two and will likely need to be moved to another genus. A genetic study published in 2019 found that the genus is strongly

polyphyletic A polyphyletic group is an assemblage that includes organisms with mixed evolutionary origin but does not include their most recent common ancestor. The term is often applied to groups that share similar features known as Homoplasy, homoplasies ...

with several groups that are quite distantly related.

Species

''Apteronotus'' contains the following recognized species: * '' Apteronotus acidops'' Triques, 2011 * '' Apteronotus albertoi'' Peixoto, Dutra, Datovo, Menezes & de Santana, 2021 * '' Apteronotus albifrons'' (

Linnaeus Carl Linnaeus (23 May 1707 – 10 January 1778), also known after ennoblement in 1761 as Carl von Linné,#Blunt, Blunt (2004), p. 171. was a Swedish biologist and physician who formalised binomial nomenclature, the modern system of naming o ...

, 1766) (Black ghost knifefish) * ''

Apteronotus anu ''Apteronotus'' is a genus of electric fish, weakly electric Gymnotiformes, knifefish in the family (biology), family Apteronotidae, distinguished by the presence of a tiny Caudal fin, tail fin. This genus is restricted to tropical and subtropi ...

'' de Santana &

Vari Vari () is a southern suburb of Athens and former municipality in East Attica, Greece along the Athens coast. The ancient Athenian deme of Anagyrous was situated here. Since the 2011 local government reform it is part of the municipality Vari-Vo ...

, 2013 * '' Apteronotus apurensis'' Fernández-Yépez, 1968 * '' Apteronotus baniwa'' de Santana & Vari, 2013 * '' Apteronotus bonapartii'' ( Castelnau, 1855) * '' Apteronotus brasiliensis'' ( J. T. Reinhardt, 1852) * '' Apteronotus camposdapazi'' de Santana & Lehmann-A., 2006 * '' Apteronotus caudimaculosus'' de Santana 2003 * '' Apteronotus cuchillejo'' ( Schultz, 1949) * '' Apteronotus cuchillo'' Schultz, 1949 * '' Apteronotus ellisi'' ( Alonso de Arámburu, 1957) * '' Apteronotus eschmeyeri'' de Santana, , Maldenado-Ocampo, Severi & G. N. Mendes, 2004 * '' Apteronotus ferrarisi'' de Santana & Vari, 2013 * '' Apteronotus galvisi'' de Santana, Maldonado-Ocampo & Crampton, 2007 * '' Apteronotus jurubidae'' ( Fowler, 1944) * '' Apteronotus leptorhynchus'' ( M. M. Ellis, )1912 (Brown ghost knifefish) * '' Apteronotus lindalvae'' de Santana & Cox Fernandes, 2012 * '' Apteronotus macrolepis'' ( Steindachner, 1881) * '' Apteronotus macrostomus'' (Fowler, 1943) * ''

Apteronotus magdalenensis ''Apteronotus'' is a genus of weakly electric knifefish in the family Apteronotidae, distinguished by the presence of a tiny tail fin. This genus is restricted to tropical and subtropical South America (Amazon, Orinoco, Río de la Plata and ...

'' ( Miles, 1945) * '' Apteronotus magoi'' de Santana, Castillo G. & Taphorn, 2006 * '' Apteronotus mariae'' ( C. H. Eigenmann & Fisher, 1914) * '' Apteronotus milesi'' de Santana & Maldonado-Ocampo, 2005 * '' Apteronotus paranaensis'' ( Schindler, 1940) * '' Apteronotus pemon'' de Santana & Vari, 2013 * '' Apteronotus quilombola'' Peixoto, Datovo, Menezes & de Santana, 2021 * '' Apteronotus rostratus'' ( Meek &

Hildebrand Hildebrand is a character from Germanic heroic legend. ''Hildebrand'' is the modern German form of the name: in Old High German it is ''Hiltibrant'' and in Old Norse ''Hildibrandr''. The word ''hild'' means "battle" and ''brand'' means "sword" ...

, 1913) * '' Apteronotus spurrellii'' ( Regan, 1914)

References

{{Authority control Apteronotidae Freshwater fish of South America Taxa named by Bernard Germain de Lacépède Freshwater fish genera