• Jiji


A ray that had been kept at an aquarium in the city of Kagoshima as a giant guitarfish for over two decades is actually a newly discovered species.

The fish, which was likely caught in waters off Kyushu, has been raised at the Kagoshima City Aquarium since its opening in 1997. The finding was reported in the Sept. 20 edition of the Ichthyological Society of Japan journal.

The giant guitarfish is designated as an endangered species by the International Union for Conservation of Nature. The new species is closely related to the giant guitarfish, said Keita Koeda, 34, a researcher from the Kuroshio Biological Research Institute in Kochi Prefecture. It is the first time in about 10 years that a new species of ray has been discovered with origins in waters around Japan, according to Koeda.

The new species was named Rhynchobatus mononoke as the fish looks like a monster wearing a triangular headpiece when seen from its belly. “Mononoke” means monsters or spirits in Japanese.

Koeda noticed a difference when he compared the ray at the aquarium with photos taken of the giant guitarfish in waters near the city of Satsumasendai, Kagoshima Prefecture, and other regions in 2018. With the help of the aquarium and the Kagoshima University Museum, he discovered that it is a new species.

The Rhynchobatus mononoke is found in waters west of the Kyushu region, which includes Kagoshima, and has a rounder nose than the giant guitarfish. It also has large black spots near the center of its pectoral fins.

Akihiko Yoshida, a 54-year-old staff member at the Kagoshima aquarium, said, “I learned again that the waters (near Kagoshima) are rich with life, including creatures that have yet to be discovered.”

“I hope the new discovery offers an opportunity to think about protecting animals at risk of extinction,” Koeda said.

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