Winghead Shark - Taxonomy and Phylogeny

Taxonomy and Phylogeny

Georges Cuvier first described a specimen of the winghead shark in 1817, as a footnote to his account of Squalus zygaena (=Sphyrna zygaena, the smooth hammerhead). Although his citation was not a proper binomial name, Valenciennes interpreted it as Zygaena Blochii nobis when he described and illustrated the winghead shark in detail in 1822. Compagno (1979, 1988) elevated the winghead shark to its own genus, Eusphyra, although this was disputed by Dingerkus (1986) on the grounds that it made the genus Sphyrna paraphyletic. Since then, the winghead shark has been listed under its own genus or as a subgenus of Sphyrna in various sources.

A phylogenetic analysis based on mitochondrial DNA by Martin (1993) showed that, contrary to the traditional (and intuitive) interpretation that the hammerheads with small "hammers" (such as the bonnethead) represented intermediate forms between the requiem sharks and those species with larger "hammers", the winghead shark was in fact the earliest of the hammerheads to diverge from their carcharhinid ancestors. This suggests that the large hammer appeared suddenly in evolutionary history, and was later modified in the other species.