After 20 years, aquarium finds out its rays are a new species
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KAGOSHIMA–It was right under their noses.
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For more than 20 years, no one was able to discern that two rays kept at a local aquarium since it first opened were actually from a previously undiscovered species.
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The rays on exhibit at the Kagoshima City Aquarium in the Honko-Shinmachi district had, until recently, been billed as a type of ray called a giant guitarfish.
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They had been part of a popular section called the Kuroshio Great Water Tank since the aquarium started operating in 1997.
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But staff said they didn’t attract much attention from visitors because the rays didn’t move around much, lingering at the bottom of the tank.
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Then, a few years ago, a researcher from the Kuroshio Biological Research Institute in Otsuki, Kochi Prefecture, examined the two rays and noticed the shape of their heads subtly differ from that of the giant guitarfish.
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The newly discovered creature is now known as a Rhynchobatus mononoke, because its triangular head resembles a “mononoke” ghost wearing a hood when seen from behind.
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The head of the new species is not as sharp as the giant guitarfish, and the ends of its two dorsal fins are rounder–subtle differences.
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The giant guitarfish can grow to a maximum of 2.5 meters long. Its body looks just like a shark, but it also has some physical features that are similar to rays.
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The Kagoshima City Aquarium jointly researched the two rays, along with the Kuroshio Biological Research Institute and the Kagoshima University Museum, before concluding that these rays come from a previously undiscovered species.
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Their findings were published in the Ichthyological Society of Japan’s international academic journal in September.
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According to the Kuroshio Biological Research Institute, it is the first time in a decade or so that a new ray species has been discovered from the seas around Japan.
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