Magosternarchus

Magosternarchus
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Gymnotiformes
Family:	Apteronotidae
Genus:	Magosternarchus Lundberg, Cox Fernandes & Albert, 1996
Type species
Magosternarchus raptor Lundberg, Cox Fernandes & Albert, 1996
Occurrences of M. raptor (red circles) and M. duccis (white squares)

Magosternarchus is a genus of weakly electric knifefish in the family Apteronotidae, containing two species. They are endemic to Brazil, occurring in large river channels in the Amazon River basin. Both species are unusual benthic predators that specialize in biting off the tails of other knifefishes, and are characterized by their greatly enlarged jaws and teeth.

The name Magosternarchus honors Dr. Francisco Mago Leccia, who has made many contributions to the study of gymnotiform knifefishes; the latter part of the name sternarchus is from the Greek sternon ("chest") and archos ("rectum"), referring to the forward placement of the urogenital opening in this group of fishes. The species name of M. raptor is from the Latin for "plunderer", referring to its tail-eating habits; the species name of M. duccis refers to the Duke University Center for Creative Ichthyology (DUCCIS), an ichthyology club. Based on several shared skeletal traits, the closest relative of Magnosternarchus is believed to be the genus Sternarchella.

Both species of Magnosternarchus are believed to range widely in the Amazon basin, including in the Rio Negro to at least above the confluence of the Branco River. M. raptor has been collected as far upstream as the lower Jutai River and as far downstream to the lower Xingu River; M. ducci has been collected as far upstream as Ica River and as far downstream as Trombetas River. They are found in large, swift-flowing whitewater and blackwater river channels, at least 10 m (33 ft) from shore, at depths of 1–23 m (3.3–75.5 ft). They are absent from beaches, small streams, and other marginal habitats.

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