Nikko, the beloved 35-year-old Oakland Zoo gibbon who had recently been sent by zoo matchmakers to soothe a lovelorn fellow gibbon in Santa Barbara, has died.

Nikko died on Sunday in Santa Barbara, en route to a veterinary clinic, of what veterinarians suspected was pancreatic cancer. A mass was discovered in Nikko’s abdomen, zoo spokeswoman Erin Harrison said.

“We are all devastated Nikko is gone. He was very special to our Oakland Zoo family. He is, and will continue to be, greatly missed by our keepers, staff and visitors alike,” said Joel Parrott, president & CEO of the Oakland Zoo.

Long a fixture in Oakland, Nikko, a white-handed gibbon, went to Santa Barbara less than one month ago as a companion to Jasmine, a Santa Barbara Zoo gibbon. Both Nikko and Jasmine had recently lost their mates. Animal matchmakers at the Association of Zoos and Aquariums thought they would be a good fit.

First introduced to one another two weeks ago, the two mopey primates immediately hit it off, Harrison said. At that time, Nikko walked over to Jasmine and gave her a hug.

“He was so sweet,” Harrison said.

But within days, Nikko began eating less and exhibiting other signs of serious illness. Santa Barbara Zoo veterinarian Julie Barnes said no treatment would have been likely to save Nikko.

Nikko was to have been a companion to Jasmine, an elderly female, and her “adopted daughter” Jari, who is 4. Nikko, Harrison said, had been lonely ever since his mate, Gladys, died in January. Nikko and Gladys sang together every morning, as gibbons do. Ever since Gladys’ death, Nikko has been silent.

Before leaving Oakland for Santa Barbara, Nikko had passed a thorough physical. After his arrival, he was eating and behaving normally, Harrison said.

Nikko’s body will be returned to the Oakland Zoo for burial.

Steve Rubenstein is a San Francisco Chronicle staff writer. Email: srubenstein@sfchronicle.com Twitter: @SteveRubeSF