Ichthyologist John Sullivan has seen his fair share of electric fishes. But when he pulled his trap out of Gabon’s Ogooué River in September 2014 he knew right away he'd found a doozy. At only about four and a half inches long, this particular electric fish was brown, almost golden, with a chin like Jay Leno. “I know these fish well enough that I can see them just for a second when I pull them from my trap and I know what they are,” Sullivan says. “And this one I was like, ‘What is that?’”

In a study released yesterday, Sullivan describes what is not only a new species, Cryptomyrus (meaning “hidden fish”) ogoouensis (named after the river whence it came), but a member of a mysterious new genus in the family of so-called weakly electric fishes. Also known as mormyrids, these don't have the shock power of the electric eel. But they generate electric fields to detect prey in the dark, and also use pulses of electricity to communicate with each other. And now they can invite a new fish into the family.

It turns out that Cryptomyrus ogoouensis' electrical pulses are as singular as its giant chin. Each species of weakly electric fish is hardwired to produce a certain waveform—that is, the shape of the pulse seen through an oscilloscope, which shows voltage over time. A mormyrid creates those pulses with a mass of modified muscle cells at the base of its tail. Each of those cells works with minute blasts of electricity, but when they all fire at the same time, they create a noticeable electric field. (Humans can feel it, but you’d only be able to pick up a slight tingle by grabbing the largest mormyrids by the tail.)

A mormyrid’s electric signature is so distinct that Sullivan can use it to identify the species—that's why he goes out of his way to catch them alive in a trap as opposed to on a line, which is more traumatic for the animal. (It also doesn’t help that Cryptomyrus ogoouensis has a super tiny mouth.) Sullivan had an inkling his catch was a new species because he didn’t recognize the recording of its electrical signals.

The other half of the mormyrid's electrical system is a set of electroreceptors. Should an insect larva—likely the fish’s preferred food—wander near, it’ll disrupt the fish's electric field and trip the predator’s electroreceptors, giving itself away. (Famously, sharks also home in on their prey by detecting an organism's electricity.) Ogoouensis also has two other kinds of electroreceptors: one to help it orient itself and navigate in the darkness, and another to detect the pulses from other weakly electric fishes.

Those are important, because mormyrids don't just hunt with those electric fields. They can also modify the rapidity of the pulses to telegraph their sex or mood. “So they can sense the timing differences in these pulses so they can say, ‘OK, there's a member of my species, and in fact that's going to be a male,’” Sullivan says.

John Sullivan

Ogoouensis isn’t alone in the Cryptomyrus genus, though: Science had another species in its grasp all along.

Sullivan’s colleagues had earlier sent him two specimens of an undescribed mormyrid, one in 2001 and another in 2012, both from Gabon. He’d held off on describing them, though, because describing a new species from one or even two specimens isn’t ideal. “Catching the one specimen of Cryptomyrus ogoouensis in 2014 rekindled our interest, and we became resigned to the fact that we weren’t getting any more specimens to work on anytime soon,” Sullivan says. Those two earlier specimens turned out to be a new species that's closely related to ogoouensis: Cryptomyrus ona, the only other species in the brand new genus.

It’s a serendipitous reminder of just how important natural history collections are to biology. Specimens don’t just soak in jars for decades, never to see fresh air again. Having a fish or beetle or sea cucumber at the ready can be pivotal for scientists trying to make sense of the tree of life—an altogether more pressing matter in the age of mass extinction.

So here’s to hoping this newfound pair of weakly electric fish species can get by alright. No sense in letting the sharks have all the fun, after all.