A New Species of Sexually Dimorphic Electric Knifefish from the Amazon Basin, Brazil (Gymnotiformes: Apteronotidae)

Santana, Carlos David de; Fernandes, Cristina Cox

doi:10.1643/ci-11-060

Cited by 12 publications

(10 citation statements)

References 23 publications

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“…Originally, this species was described as Sternarchus leptorhynchus Ellis in Eigenmann, 1912, but in a revision of the Gymnotiformes, it was reassigned to the genus Apteronotus Lacepède, 1800 (Mago-Leccia 1994). It inhabits rivers and streams of the Atlantic drainage basins east of the Andean Cordilleras, the Caribbean versant of north-west South America, and the Pacific slope of Colombia and Panama (de Santana and Cox Fernandes 2012). Recently, de Santana and Vari (2013) proposed the division of the monophyletic A. leptorhynchus species group into two major clades: (1) the A. leptorhynchus clade composed of six cis-Andean species and (2) the Apteronotus rostratus (Meek and Hildebrand, 1913) clade consisting of three trans-Andean species.…”

Section: Sampling and Taxonomic Considerationsmentioning

confidence: 99%

Indeterminate body growth and lack of gonadal decline in the brown ghost knifefish (Apteronotusleptorhynchus), an organism exhibiting negligible brain senescence

2014

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The brown ghost knifefish (Apteronotus leptorhynchus (Ellis in Eigenmann, 1912)) is the only vertebrate organism identified thus far that exhibits negligible brain senescence. The present study examines the basic growth patterns of this species, testing the hypothesis that indeterminate growth and lack of reproductive senescence correlate with negligible senescence. Analysis of length-mass relationships revealed negative allometric growth in males and isometric growth in females. Total length at first sexual maturity was 13.5 cm in males and 12.0 cm in females, whereas gonadal mass was 0.02 g in males and 0.2 g in females. Modelling of total length as a function of the number of otolith rings using attenuating growth equations revealed that lengths of up to 26.8 cm in males and 20.2 cm in females can be reached, indicating that the fish continue to grow throughout life. Gonadal mass increased significantly with age in sexually immature individuals of both sexes. In sexually mature fish, gonadal mass showed a marginal increase with age in males and no change in females. The demonstration of indeterminate growth of the fish and of the lack of gonadal regression with age has important implications for the characterization of brown ghost knifefish as a model of negligible senescence.Résumé : Le poisson-couteau brun (Apteronotus leptorhynchus (Ellis in Eigenmann, 1912)) est le seul organisme vertébré identifié à ce jour qui présente une sénescence négligeable du cerveau. L'étude se penche sur les motifs de croissance de base de cette espèce afin de vérifier l'hypothèse voulant que la croissance indéterminée et l'absence de sénescence reproductrice soient corrélées à une sénescence négligeable. L'analyse des relations longueur-masse a révélé une croissance allométrique négative chez les mâles et une croissance isométrique chez les femelles. La longueur totale à l'atteinte de la maturité sexuelle était de 13,5 cm pour les mâles et de 12,0 cm pour les femelles, alors que la masse des gonades était de 0,02 g pour les mâles et de 0,2 g pour les femelles. La modélisation de la longueur totale en fonction du nombre d'anneaux d'otolithe à l'aide d'équations d'atténuation de la croissance a révélé que des longueurs de jusqu'à 26,8 cm pour les mâles et 20,2 cm pour les femelles peuvent être atteintes, ce qui indique que les poissons continuent de croître tout au long de leur vie. La masse des gonades augmentait de manière significative avec l'âge chez les individus sexuellement immatures des deux sexes. Chez les poissons sexuellement matures, la masse des gonades présentait une augmentation marginale avec l'âge chez les mâles et aucun changement chez les femelles. La démonstration de la croissance indéterminée de ces poissons et l'absence de régression des gonades avec l'âge ont d'importantes conséquences en ce qui concerne la caractérisation du poisson-couteau brun en tant que modèle de sénescence négligeable. [Traduit par la Rédaction]Mots-clés : neurogénèse adulte, Apteronotus leptorhynchus, poisson-couteau brun, croissance ...

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Section: Sampling and Taxonomic Considerationsmentioning

confidence: 99%

Indeterminate body growth and lack of gonadal decline in the brown ghost knifefish (Apteronotusleptorhynchus), an organism exhibiting negligible brain senescence

2014

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“…: 242 [Río Meta]. – de Santana & Cox‐Fernandes, : 284 [Río Orinoco basin; occurrence in streams; presence of secondary sexual dimorphism].…”

Section: Taxonomic Accountsmentioning

confidence: 98%

“…Albert & Campos‐da‐Paz () and Albert (), followed by de Santana & Cox‐Fernandes (), proposed a slightly more encompassing assemblage than the A. leptorhynchus species‐group of this analysis, which additionally incorporated Apteronotus brasiliensis and which they termed the A. brasiliensis species‐group. In so far as the data matrices of the analyses Albert & Campos‐da‐Paz () and Albert () did not include A. brasiliensis , the basis for that assignment is uncertain.…”

Section: Taxonomic Accountsmentioning

confidence: 99%

“…– Albert, : 46 [in part; Guyana; not citations from other regions of Guiana Shield]. – de Santana & Cox‐Fernandes, : 284 [Essequibo River basin; occurrence in streams].…”

Section: Taxonomic Accountsmentioning

confidence: 99%

“…– Lasso et al ., : 142 [western Orinoco basin]. – de Santana & Cox‐Fernandes, : 284 [Río Orinoco basin; occurrence in rivers].…”

Section: Taxonomic Accountsmentioning

confidence: 99%

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Brown ghost electric fishes of theApteronotus leptorhynchusspecies-group (Ostariophysi, Gymnotiformes); monophyly, major clades, and revision

Santana

Vari

2013

Zool J Linn Soc

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Neotropical brown ghost electric knifefishes of the Apteronotus leptorhynchus species‐group are reviewed. A series of synapomorphies delimit the species‐group and the two major subunits that comprise that clade. The phylogeny is concordant with the hypothesis of a primary division within the clade resultant from Andean uplift events 8 Mya and with the existence of ancestral components of the species‐group 12 Mya. Species of the species‐group are characterized by morphological stasis across that time frame. Apteronotus leptorhynchus, previously considered to be a widely distributed and morphologically variable species, was found to encompass five species. The description of the four new species is supplemented by the redescription of the five previously recognized forms within the species‐group. Members of this clade are broadly distributed through the Essequibo River and Río Orinoco of the Atlantic slope of South America, the Ríos Aroa, Atrato, Cauca, Magdalena, and Yaracuy, and the rivers of the Lago Maracaibo basin of the Caribbean slope and drainages in northern Colombia and Panama along the Pacific versant. © 2013 The Linnean Society of London

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Harmonic and temporal structure of electric organ discharges of the wave-type in Amazonian knifefishes (Gymnotiformes)

Kramer

2018

J Ethol

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A New Species of Sexually Dimorphic Electric Knifefish from the Amazon Basin, Brazil (Gymnotiformes: Apteronotidae)

Cited by 12 publications

References 23 publications

Indeterminate body growth and lack of gonadal decline in the brown ghost knifefish (Apteronotusleptorhynchus), an organism exhibiting negligible brain senescence

Indeterminate body growth and lack of gonadal decline in the brown ghost knifefish (Apteronotusleptorhynchus), an organism exhibiting negligible brain senescence

Brown ghost electric fishes of theApteronotus leptorhynchusspecies-group (Ostariophysi, Gymnotiformes); monophyly, major clades, and revision

Harmonic and temporal structure of electric organ discharges of the wave-type in Amazonian knifefishes (Gymnotiformes)

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