Common Thresher - Taxonomy and Phylogeny

Taxonomy and Phylogeny

The first scientific description of the common thresher, as Squalus vulpinus, was written by French naturalist Pierre Joseph Bonnaterre in the 1788 Tableau encyclopédique et méthodique des trois règnes de la nature. In 1810, Constantine Samuel Rafinesque described Alopias macrourus from a thresher shark caught off Sicily. Later authors recognized the genus Alopias as valid while synonymizing A. macrourus with S. vulpinus, and thus the common thresher's scientific name became Alopias vulpinus.

The specific epithet vulpinus is derived from the Latin vulpes meaning "fox", and in some older literature the species name was given incorrectly as Alopias vulpes. "Fox shark" is the earliest known English name for this species and is rooted in classical antiquity, from a belief that it was especially cunning. In the mid-19th century, the name "fox" was mostly superseded by "thresher", referencing the shark's flail-like use of its tail. This species is often known simply as thresher shark or thresher; Henry Bigelow and William Schroeder introduced the name "common thresher" in 1945 to differentiate it from the bigeye thresher (A. superciliosus). It is also known by many other common names, including Atlantic thresher, grayfish, green thresher, long-tailed shark, sea ape, sea fox, slasher, swiveltail, thintail thresher, thrasher shark, and whiptail shark.

Morphological and allozyme analyses have agreed that the common thresher is basal to the clade formed by the bigeye thresher and the pelagic thresher (A. pelagicus). The closest relative of this species within the family may be a fourth, unrecognized thresher shark species off Baja California, reported from allozyme evidence by Blaise Eitner in 1995. However, the existence of this fourth species has yet to be confirmed by other sources.