Crevalle Jack - Taxonomy and Phylogeny

Taxonomy and Phylogeny

The crevalle jack is classified within the genus Caranx, one of a number of groups known as the jacks or trevallies. Caranx itself is part of the larger jack and horse mackerel family Carangidae, a group of percoid fishes in the order Perciformes. The species belongs to what William Smith-Vaniz and Ken Carpenter refer to as the Caranx hippos complex, a group of closely related fishes which also includes Caranx caninus (Pacific crevalle jack) and Caranx fischeri (longfin crevalle jack).

The crevalle jack was the first species of its genus to be scientifically described and named, and is also the type species of the genus Caranx. It was described and named in 1766 by the famed Swedish taxonomist Carolus Linnaeus, based on the holotype specimen taken off the coast of the Carolinas, USA. He named the species Scomber hippos, placing it in the mackerel genus Scomber, a practice which was common prior to 1801 when the carangids were not yet recognised as separate from the scombrids. The specific epithet means "horse" in Latin, with Scomber hippos literally translating in English as "horse mackerel", which has become a common name for many species of carangid. As the state of fish taxonomy progressed, the species was transferred to both Caranx and Carangus, with the name Caranx hippos now accepted. Bernard Germain de Lacépède was the first person to separate the crevalle jack from the mackerels, placing it in its own genus Caranx, although he had redescribed the fish as Caranx carangua, which became the type species of Caranx. As well as Lacepede's renaming, the species has been independently redescribed a total of six times, with all of these names, including Lacepede's, categorised as invalid junior synonyms under ICZN rules.

There has been extensive discussion in the scientific literature regarding the possible conspecifity of the Pacific crevalle jack, Caranx caninus, with Caranx hippos. Arguments ranged from the species being conspecific, subspecific or as individual species. This led to the creation of two trinomial names; Caranx hippos hippos and Caranx hippos tropicus. The former was an attempt to separate the 'subspecies' on each side of the Americas, while the latter was an unnecessary name to divide the Atlantic Caranx hippos into subspecies. The most recent review of the species complex by Smith-Vaniz and Carpenter treated the fish as separate species, citing differences in the development of hyperostosis and differing anal fin colours as evidence of species status. The species' most often used common name, crevalle jack (or 'jack crevalle') is based on the word "cavalla", an earlier word used for the jacks. Other names include common jack, black-tailed trevally, couvalli jack, black cavalli, yellow cavalli and a host of generic names, such as horse mackerel and crevalle.