An endangered fish is actually two even more endangered fish, according to new research.

Although it is already listed as ‘critically endangered’ the poor old European common skate may be in an even worse state than we thought. A new paper published in Aquatic Conservation says what we thought was the skate Dipturus batis is actually two different animals.

“Morphology, genetics, and life history reveal that two distinct species have been erroneously confused since the 1920s under the single scientific name D. batis,” write Samuel Iglésias, of the French National Museum of Natural History, and colleagues.

Iglésias says the ‘common skate’ species should be split into the blue skate (provisionally D. cf. flossada) and the flapper skate (D. cf. intermedia). This is not just of academic importance.

“Revisions of incorrect synonymizations – called species resurrections – are common works for systematists, but in the present case the resurrection of D. cf. intermedia is of great conservation significance,” the authors note.

The problem is that the not-quite-so-bad state of blue skate populations has been masking the really, really bad state of the flapper. And the old ‘common skate’ is already noted as the first fish brought to the brink of extinction by commercial fishing and this confusion of blue and flapper has hamstrung those trying to conserve the species – both of which deserve independent ‘critically endangered status’ says the paper.

“The risk of extinction of these depleted species is higher than previously assessed and appears unavoidable without immediate and incisive conservation action,” Iglésias concludes.