The jack-knifefish was first formally
described as
Chaetodon lanceolatus in 1758 by
Carl Linnaeus in the 10th edition of his
Systema Naturae with its
type locality given, erroneously as India, when it should have been the Bahamas. In 1793 the German
physician and
naturalist Marcus Elieser Bloch described a new species,
Eques americanus, from the Western Atlantic and placed it in the new monospecific genus
Eques. Bloch's genus name was considered to be preoccupied by a name Linnaeus had used for a subgenus of
Papilio, and
Constantine Samuel Rafinesque created
Equites to replace Bloch's
Eques, however, Linnaeus's name is considered to be invalid so
Eques is now considered valid. Fishbase treats the genus as monospecific with this species as the only species but the 5th edition of
Fishes of the World does not recognise subfamilies within the Sciaenidae which it places in the
order Acanthuriformes. ==Description==