Apteronotus
genus of fishes
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 Magdalena basins, as well as rivers in western Colombia and the Guianas) and Panama 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 18–50 cm (7–20 in). Although it has been claimed that A. magdalenensis is up to 130 cm (4.3 ft) long, this is not supported by recent studies and likely the result of confusion with Sternopygus aequilabiatus. Members of Apteronotus fall into three species groups based on their morphology: 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 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, 1766) (Black ghost knifefish)
Apteronotus anu de Santana & Vari, 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 (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, 1913)
Apteronotus spurrellii (Regan, 1914)
The following cladogram is based on a 2019 phylogenetic study analyzing both mitochondrial and nuclear gene sequences of Apteronotidae.
This brief starts where responsible research should: with the source description of “Apteronotus” as genus of fishes. Everything that follows is an evidence route, not borrowed authority.
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The subject matters to the science & nature register because the source frames it as genus of fishes. Its deeper value depends on whether names, dates, institutions and citations support that framing.
The date and method of observation matter as much as the stated conclusion, especially where classification or consensus has changed. The source revision retrieved here is dated Aug 5, 2026. The linked authority identifier is Q2859065. None of the 0 selected statements returned an explicit reference. The first chronological checks are 2019, 2011, 2021 and 1766.
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This entry incorporates text from “Apteronotus” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.