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Magosternarchus, a New Genus with Two New Species of Electric Fishes (Gymnotiformes: Apteronotidae) from the Amazon River Basin, South America

John G. Lundberg, Cristina Cox Fernandes, James Spurling Albert and Marcelo Garcia
Copeia
Vol. 1996, No. 3 (Aug. 1, 1996), pp. 657-670
DOI: 10.2307/1447530
Stable URL: http://www.jstor.org/stable/1447530
Page Count: 14
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Magosternarchus, a New Genus with Two New Species of Electric Fishes (Gymnotiformes: Apteronotidae) from the Amazon River Basin, South America
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Abstract

A new group of predaceous apteronotid electric fishes is described from recent trawl collections made in large, white- and black-water river channels of the Amazon Basin in Brazil. Magosternarchus, n. gen., is diagnosed by greatly enlarged jaws and teeth. The type species, Magosternarchus raptor, n. sp., possesses uniquely enlarged premaxillary bones and an associated hypertrophied mesethmoid. Magosternarchus duccis, n. sp., is unique in its strongly projecting lower jaw that includes and often extends dorsal to the upper jaw and snout. The only identifiable stomach contents in specimens of both species of Magosternarchus are tails of other gymnotiform fishes. Shared features of the ethmoid and jaw bones, mesopterygoid, opercle, gillrakers, basibranchials, and infraorbital laterosensory canal suggest that Magosternarchus is most closely related to Sternarchella. /// Um novo grupo de peixes elétricos predadores, capturados recentemente com redes de arrasto, é descrito proveniente de canais de rios da Bacia Amazônica Brasileira. Magosternarchus, gen. nov., é diagnosticado pela presenca de dentes e de mandíbulas bem desenvolvidas. A espécie tipo, Magosternarchus raptor, sp. nov., possui umã expans ão dos premaxilares associada ao mesetmóide hipertrofiadã que é única entre os peixes elétricos. Magosternarchus duccis, sp. nov., é diferenciado por apresentar a mandibula inferior prolongada, a qual se extende dorsalmente sobre a mandibula superior e o focinho. O único material identificado no conteúdo estomacal dos especimens das duas espécies de Magosternarchus foram elementos das nadadeiras caudais e das vértebras de outros peixes elétricos. Caracteres comuns relativos aos ossos etmóide e das mandíbulas, mesopterigóide, opérculo, rastros branquiais, elementos do basibranquial e canal do infraorbital sugerem que Magosternarchus é filogeneticamente mais próximo do gênero Sternarchella.

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