Preserved Specimens Yield New Electric Fish Find

Scientists don’t prefer to describe new species of anything with only just a few specimens to base their descriptions off of. But in the case of two new electric fishes discovered in Gabon, an African republic, researchers simply had to make due with the fish they had.

Researchers from Cornell University’s Museum of Vertebrates had come across the electric fishes only twice before, once in 2001 and again in 2012. Each of those was left undescribed, but researchers did know they were mormyrids.

The first specimen was collected in 2001 in the Nyanga River in Gabon. The second was gathered in Gabon’s Ngounié River. Finally, in 2014, during an expedition to Gabon’s Ogooué River, funded by Gabon’s science agency and The Nature Conservancy, the third fish was caught.

So after finding another of the fish type in Gabon in 2014, scientists at the museum knew it was time to set about describing the fish because there were simply too few being found to warrant waiting any longer. The researchers took out the first two fish discovered, which had been preserved, and began comparing their DNA to the one most recently found.

All of the specimens were electric fish, though not electric enough to be compared to eels or other shocking fish. But further inspection showed that the fish didn’t belong to an already-described genus within the Mormyridae family. And so the researchers set out to describe a whole new genus for the fish.

The researchers named the new genus Cryptomyrus, which comes from Greek words meaning “hidden fish” since they are rare in natural history collections. And two new species of fish were found: Cryptomyrus ogoouensis and Cryptomyrus ona. The first two specimens captured, as it turned out, were part of a species all their own.

These mormyrid fishes are called “weakly electric” fish because they don’t have a large amount of shocking power. Instead, their low-level electricity gets used in helping them to detect prey fish in the dark. Their electric pulses can also be used in communicating with other fishes that are related to them things like their mood or state of sexual arousal. In addition, researchers say that some species of the fish have electric receptors that they use to orient themselves in the water.

What’s also neat about these new electric fish is that each species has its own electric pulse that it relies on for hunting and identification. This trait is hardwired and can’t change, so each species has sort of an electric “wave-print” that helps to describe it.

Researchers involved with the discovery say that it is proof of the value of natural history collections that keep such specimens and their DNA in good condition so further study can be done. It can take years or decades to connect all the dots, they note, which is why such collections should be maintained.

More than 200 species of mormyrid fish live in fresh waters across Africa where they communicate with weak electric organ discharges produced from an organ in front of their tail. For more on the newest members of this group, see the study’s full results published online.

 

Top image: Specimens of two newly-described electric fish species, Cryptomyrus ogoouensis and Cryptomyrus ona, discovered in Gabon. (Credit: John Sullivan / Cornell University)

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