Photo/IllutrationThird-year students Hitomi Momosaka, left, Haruka Asanabe, center, and Akiko Hirano and other members of Nagasaki Nishi High School's biology club discovered a new water strider species. (Tsuyoshi Nakagawa)

  • Photo/Illustraion

NAGASAKI--Three female high school students doubted the experts, doubled down on their research and discovered the first new water strider species in 60 years in Omura Bay.

Haruka Asanabe, 18, Akiko Hirano, 17, and Hitomi Momosaka, 17, all third-year students at the prefecture-run Nagasaki Nishi High School, co-authored the report of their finding that was published in the online edition of the international academic journal Canadian Entomologist.

The new species has been named Nagasaki Amenbo in Japanese.

The three students worked with Tetsuya Nagashima, a 59-year-old teacher who is an adviser to the school’s biology club, and Tomohide Yasunaga, 54, a research associate of the American Museum of Natural History who lives in Nagasaki and is familiar with water striders and other stinkbug species.

Last spring, Asanabe, Hirano and Momosaka began studying several water strider species found along Omura Bay, including an endangered one. Many of the striders they found on the water surface had long bodies.

However, experts have stated that all striders in coastal areas have round bellies. If striders with long and narrow abdomens are found there, they are a species known as Aquarius paludum paludum that inhabit fresh water rivers and are accidentally carried to the ocean, according to the experts.

But the three students discovered so many long-body striders elsewhere in Omura Bay that they believed they must be endemic to the coastal region.

They carried out surveys at 57 locations around the bay from morning to evening on weekends as well as the summer holidays with the help of Nagashima, who drove them to the locations, and other club members.

During the research period, they drove around the 360-kilometer circumference of the bay five times.

To more closely examine the striders, the students developed equipment to keep the species.

One big challenge they faced was how to prevent proliferated bacilli from forming a membrane on the surface of the seawater in the tank, which made it difficult for striders to travel on.

After two months of research, the students found that continually supplying water drops to the surface could prevent the membrane from being formed.

The completed equipment, made of drawers for clothing and other goods, enabled the bug to lay and hatch eggs.

Asanabe, who headed the team of three students, said she “almost gave up when failing to establish the method to keep” the new species. But she said she could achieve big results because “I did not give up then.”

Electron microscopy and vacuum experiments showed that the long-body water skipper the students found along Omura Bay was different from Aquarius paludum paludum in terms of the length of legs and antennae, as well as the shapes of eggs, genitalia and other features.

The salt concentration levels at which the bugs can hatch and survive, the places where they lay their eggs, and other habits were also different between the two species.

Based on those findings, the students concluded the strider was a new species that hatches and grows in brackish waters where seawater and fresh water are mixed.

Hirano recalled the difficult days of research.

“I had to work until late at night to finish the experiments, thesis and study for school exams,” she said.

Momosaka described their efforts as “the best memory in my high school days.”

“It marked the first time in 60 years for a new strider species to be found,” Yasunaga said. “What is most important is the students’ curiosity about the research. The thesis will inspire researchers to review the conventional categorization.”