Mystery of electric fish classification solved, new class identified

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Solving a 140-year aged taxonomic puzzle, Cornell researchers have identified and described a new class of electric fish from a Ogooué River in Gabon, Africa.

The new species, named Paramormyrops ntotom, belongs to a family Mormyridae, and is partial of a organisation called a “species flock” – closely associated class that are identical in coming and all live in a same region.

The researchers, who published their formula in a Zoological Journal of a Linnean Society, identified a new class by anatomical measurements, genetics and analyses of a diseased electric beat a fish evacuate called an electric organ discharge, or EOD. These information helped renowned P. ntotom from another formerly described fish that belongs to a same classification and class flock, called Paramormyrops sphekodes, that was initial described in 1879.

Comparisons of Paramormyrops ntotom and P. sphekodes specimens, display how a physique measurements and EOD waveforms differ. P. sphekodes has a somewhat smaller body, shorter conduct and shorter EOD than P. ntotom. Credit: John Sullivan

A French path-finder initial identified P. sphekodes after collecting dual specimens in 1877 circuitously a encampment of Doumé, that lies along a Ogooué River. Those specimens, that offer as a anxiety for a species, are recorded in a National Museum of Natural History in Paris, though are too degraded to scrupulously analyze. Because other associated class in a classification Paramormyrops so closely resembled P. sphekodes, they have been wrongly personal as P. sphekodes given a late 1800s.

“P. sphekodes, described in 1879, was a initial of what we now know are many class in this genus,” pronounced John Sullivan, a co-author on a paper and curatorial associate during a Cornell Museum of Vertebrates. “It being a first, when people collected other ones after they only practical a P. sphekodes name to those specimens, though a lot of them clearly are not a same thing. It was never unequivocally transparent how to heed this one from a others. In this study, we do that for a initial time.”

In sequence to solve a mystery, Sullivan returned to a strange site (called a form locality) circuitously Doumé where a anxiety or type-specimens for P. sphekodes were held in a 1800s. There, and in another plcae along a Ogooué River 45 kilometers away, Sullivan used fish traps to locate new specimens during dual expeditions, in 2011 and another in 2014 sponsored by The Nature Conservancy.

Among a Paramormyrops fish Sullivan collected, one accumulation had a brief EOD, while a other had a longer one, a disproportion suggested by an amplifier with dual electrodes placed in a water.

From these uninformed samples, Sullivan and his colleagues – co-author Carl Hopkins, highbrow emeritus of neurobiology and behavior, and initial author Madeline Rich, an undergraduate in Hopkins’ lab – used complicated techniques to investigate a fish.

Rich done anatomical measurements from a bodies and also from X-rays of a newly held fish during a Cornell University Museum of Vertebrates. The measurements showed that there were pointed differences in meant physique distance and conduct proportions. At a Fuller Evolutionary Biology Lab in a Cornell Lab of Ornithology, Rich also performed DNA sequences of a fish that offering justification that a dual fish varieties do not interbreed.

By comparing conduct measurements with a 1879 anxiety specimens, a researchers were means to heed P. sphekodes – that had a shorter EOD and a smaller physique and shorter conduct – from a new species, P. ntotom (ntotom is a word from a Fang denunciation of Gabon that means “mormyrid fish”).

“This is a good instance of bringing opposite kinds of information together to solve a formidable taxonomic question,” pronounced Hopkins. “It unequivocally demonstrates a utility of revisiting form localities and recording EODs for mormyrid fish taxonomy.”

They were means to re-describe P. sphekodes, while also formulating a horizon for specifying class belonging to a Paramormyrops genus.

More than 200 famous class of mormyrid fish live in uninformed waters opposite Africa, and their EODs are singular to any species. The fish use them to promulgate class identity, as good as sex temperament in some class where males and females have opposite EODs. The pulses also assistance them electrolocate, or navigate, as special tail sensors collect adult distortions caused by circuitously objects within their self-produced electric fields.

Source: Cornell University

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