A lateral view of the Apristurus ovicorrugatus. The first is a fresh sample, while the second is preserved. JOURNAL OF FISH BIOLOGY

A mysterious egg led researchers to discover a new species of shark, according to a recent scientific paper.

Researchers from Australia, Japan and France said in their paper in the Journal of Fish Biology they had identified a new species of deepwater catshark, called Apristurus ovicorrugatus. The shark is from northwestern Australia and was identified because of unique egg cases found in an Australian museum in 2011.

Two other identical egg cases were recently found in the Australian National Fish Collection. A dead female shark carrying the same egg case was also found in storage. It had been incorrectly labeled when found in 1992, but the egg case found inside it matched the unusual characteristics of the other egg cases.

The egg cases have strong T-shaped ridges, the paper's authors said. The unique markings resembled multiple other species, but none of the characteristics fully matched existing shark egg cases. One of the recently found egg cases contained what researchers described as a well-preserved, late-term shark embryo.

Scientists used multiple methods, including molecular analysis, to identify the species. Researchers named the Apristurus ovicorrugatus after the corrugated egg cases that led them to the discovery. That corrugated design is unique to the species, since other egg cases laid by sharks in the Apristurus category do not have such markings. It's unclear why the design has developed, but researchers suggested that possible benefits could include helping the embryo develop or strengthening the egg case against shock.

In addition to the unique egg case, the researchers found that the Apristurus ovicorrugatus would have bright white eyes, which are unusual among deep-water organisms. Only one other type of Apristurus catshark has that feature, but because the egg cases are so different, researchers were able to determine they were two different species.

Apristurus catsharks are also known as ghost or demon catsharks. There are about 40 identified catshark species, but the number of species in the genus is "continually increasing" due to new discoveries, researchers said. Nine species have been found in the last 20 years.

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