Back in 1999, a group of scientists working in the Arafura Sea found something more in their nets than they’d expected. Funded by the American National Science Foundation, they were looking for biodiversity within Australian fishes: gut parasites known as cestodes, or tapeworms. What they found was a new species of whipray. They just didn’t know it at the time.

The scientists kept a tissue sample and sent a photo of the giant stingray to our Australian National Fish Collection in Hobart, hoping for an ID. But researchers there did not know of a stingray in the Indo-Pacific of such a large size and finely blotched yellowish-grey colour.

The question rested for about a decade until DNA analysis of the tissue sample confirmed the mystery ray was distinct from all other known stingray species.

A photo and a DNA sequence are not enough to describe and name a new species, let alone begin to understand and perhaps try to conserve it. But surely it wouldn’t be too hard to find more specimens? It’s not often that scientists discover a new species so large: the width of the mystery ray is at least 1.6 m, making it one of the largest stingrays known.

Before too long, Peter Kyne of Charles Darwin University caught three unidentified rays in the tidal rivers of Kakadu National Park while researching northern Australian euryhaline elasmobranchs (sharks and rays that don’t mind a bit of fresh water) under the National Environmental Research Program. Again, only tissue samples were kept, this time due to permit restrictions. DNA analysis by Gavin Naylor at the College of Charleston in the US revealed a match to the mystery ray from the Arafura Sea.

Read further at the CSIRO Blog.