New expedition looks for shark mating sites
A mysterious egg has led researchers to discover a new species of shark, according to a recent scientific paper.
Researchers from Australia, Japan and France report in their paper in the Journal of Fish Biology that they have identified a new species of deep-water catshark, named Apristurus ovicorogatus. The shark is from northwestern Australia and was identified in 2011 in a unique egg case found in an Australian museum.
Two other identical egg cases have recently been found in the Australian National Fish Collection. A dead female shark carrying the same egg case was also found in storage. It was mislabeled when it was found in 1992, but the egg case found inside it matched the unusual features of other egg cases.
Journal of Fish Biology
The egg cases have strong T-shaped ridges, the paper’s authors said. The unique markings are similar to those of several other species, but none of the features exactly match those of extant shark eggs. One recently found egg case contained what researchers described as a well-preserved, late-term shark embryo.
Scientists used multiple methods, including molecular analysis, to identify the species. The researchers named Apristurus ovicorogatus after the corrugated egg cases that led to their discovery. This corrugated pattern is unique to the species, as other shark eggs in the section Apristurus do not have such markings. It’s not clear why the design evolved, but the researchers suggest that possible benefits could include aiding the development of the embryo or strengthening the egg case against shock.
Journal of Fish Biology
In addition to the unique egg case, the researchers found that Apristurus ovicorrugatus will have bright white eyes, which are unusual among deep-water organisms. Only one other type of apristurus catshark has that characteristic, but the egg cases are so different, researchers were able to determine that they are two different species.
Apristurus catshark is also known as ghost or monster catshark. There are about 40 identified catshark species, but the number of species is “constantly increasing” due to new discoveries, the researchers said. Nine species have been found in the last 20 years.
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