New species of shark identified after unique egg cases found in museum

A team of ichthyologists from CSIRO National Research Collections Australia–Australian National Fish Collection, Hokkaido University and Sorbonne Université, EPHE has discovered a new species of deepwater shark after identifying egg cases found in a museum. In their study, reported in Journal of Fish Biology, the group found the shark after discovering unique shark egg cases in two Australian museums.

In 2011, a prior research team came across a unique shark egg case. A search of known shark egg cases came up empty, leaving the species that had laid the egg unidentified. Most sharks give birth to live young, but a few species, known as oviparous sharks, lay eggs.

In such species, the eggs are housed in protective casings, which are sometimes referred to as "mermaids' purses." Most shark cases also have long tendrils that allow for attaching to rocks or seaweed. The egg cases found in 2011 had unique ridges along their length—they were believed to have come from a species belonging to the Apristurus genus. They were also unique in that they had been found attached to coral.

Approximately a decade later, two more of the egg cases were identified—both housed at the Australian National Fish Collection. That led the research team to look a little deeper—they began searching databases for Apristurus-type sharks sighted around the same areas in which the egg cases were found. That led them to a shark that had been misidentified. The research team discovered the misidentified shark had been pregnant when she died, and her body contained a single egg case that matched the three found in the museum.

The group named the new species Apristurus ovicorrugatu, after ovi and the corrugated appearance of the egg case. They plan to take a fresh look at other shark specimens in museums to find out if others have been misidentified, starting with examination of egg cases.

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