A new species of shark has been discovered in the deep waters off the coast of New Zealand, according to a new study, which has also described an entirely new family made up of previously described species – the bristle sharks,
The new species, named the roughback bristle shark (Dichichthys satoi) is a type of catshark, and was identified from specimens taken from natural history museums, with additional observations of live animals during deep-water surveys of the western Pacific Ocean, from Japan to Australia, Papua New Guinea, and New Zealand.
The new family of bristle sharks consists of the newly identified species, plus four other species that were previously grouped together with other families of catsharks. Differences between the shapes of the eyes, dorsal fins, reproductive organs and egg-cases, however, prompted the new Dichichthyidae family grouping, which was later confirmed by genetic differences between the varying species.
One of the most significant differences is the structure of the sharks’ denticles – the tooth-like structures that make up the external layer of a shark’s skin – which in the new species are described as ‘bristle-like’ in appearance – hence the name.
The newly described roughback bristle shark is described as having a ‘relatively firm’, medium to greyish brown body with a compressed and tapering tail, an abdomen longer than its head, and a ‘prominent crest of enlarged denticles on the dorsal and ventral midline of its caudal peduncle’ – the part of a fish’s body which connects its body to the tail. It can be distinguished from the other members of the new family by the white margins aroundd its fins.
The bristle sharks are relatively large animals, measuring up to 1 metre in length, and the different species have been found in waters ranging between 500 – 1500m in depth across the Western Pacific, although so far the new roughback bristle shark has been observed only in the water off New Zealand.
The team behind the new study writes that the identification of the new species lays the foundation for a ‘taxonomic revision of the catshark families and genera’, some of which are ‘in urgent need of revision.’
The complete paper, ‘Dichichthyidae, a New Family of Deepwater Sharks (Carcharhiniformes) from the Indo–West Pacific, with Description of a New Species’, by William T White et al is published in the online journal Fishes.
