Cryptic diversity and species assignment of large lantern sharks of the Etmopterus spinax clade from the Southern Hemisphere (Squaliformes, Etmopteridae)

Abstract

Straube, N., Kriwet, J. & Schliewen, U. K. (2010). Cryptic diversity and species assignment of large lantern sharks of the Etmopterus spinax clade from the Southern Hemisphere (Squaliformes, Etmopteridae). —Zoologica Scripta, 40, 61–75.Many species of the speciose deep‐sea shark family Etmopteridae (lantern sharks) are a regular by‐catch component of deepwater trawl and longline commercial fisheries. As for many elasmobranchs, the low fecundity, late sexual maturation and extreme longevity of the lantern sharks increase their susceptibility to overfishing. However, the taxonomic uncertainty within etmopterids and the poorly known patterns of dispersal of these shark species hampers the establishment of reasonable monitoring efforts. Here, we present the first molecular approach to clarify the taxonomy and distribution of a morphologically uniform group of lantern sharks comprising Etmopterus granulosus and closely related congeners by using nucleotide sequence data from the mitochondrial DNA cytochrome oxidase I gene and amplified fragment length polymorphisms. Samples were collected from several locations in the Southern Hemisphere, where the species occur. Our analyses reveal a high level of cryptic diversity. E. granulosus is not endemic to Chile, but instead has a widespread distribution in the Southern Hemisphere being synonymous to New Zealand Etmopterus baxteri. Conversely, specimens previously assigned to E. baxteri from off South Africa apparently represent a distinct species. Our results provide the basis for the re‐description of E. granulosus and E. baxteri which will help in the establishment of useful monitoring and management strategies.