A new wrinkle has appeared in Hawai'i's ever-growing population of invasive chirping frogs: Colossal coquis. Titanic tree toads. Humungous Eleutherodactylus, to elaborate on their scientific name.

The normally diminutive amphibians with the amplified shriek are suddenly going jumbo on the Big Island — as big as tennis balls, some say.

State agriculture officials can't confirm that claim, but do say Big Island coqui frogs are getting bigger.

While most of the adults are still about the size of a 25-cent piece — which is an inch in diameter — a few popping up on the Big Island have been compared to the size of Morgan silver dollars, which are a full inch and a half wide.

That's a 50 percent growth spurt.

Coquis have not, however, ballooned to the size of tennis balls, insisted Janelle Saneishi, spokeswoman for the state Department of Agriculture.

"Maybe golf balls, but not tennis balls," she said.

The tennis ball-sized coqui report stemmed from Mark Munekato of the Hawaii Island Economic Development Board, who told a Big Island newspaper reporter on Tuesday that a coqui frog that large had been spotted.

The next day, an article appeared in the paper with a headline stating, "invasive species mutates."

"Actually, that article was the first time I heard that there were giant coqui frogs," Saneishi said.

Neil Reimer, chief of the Ag Department's plant pest control branch, was also caught off guard.

"It's news to me — it's the first I've heard of this," Reimer said. But, after checking with his staff in the field, he confirmed that the frogs have increased in size since arriving in Hawai'i in the 1990s.

Still, the bigger coqui frogs seem to be confined to the Big Island.

"The picture (of a larger coqui) that one of our administrators sent me was from the Big Island," Saneishi said. "I don't think we have any of those giant ones here on O'ahu."

That photo shows a coqui of the "silver dollar size" variety, according to the administrator, Sane-ishi said — although it's difficult to know precisely how big the thing is. The creature, with its rubbery, unwebbed ET "fingers," is seen lounging on the edge of a potted plant. But there's nothing in the photo to compare it to.

Saneishi disputed the notion that the big coqui frogs are mutants.

Coquis, she explained, "have no natural predators in Hawai'i like they do in Puerto Rico, where you've got snakes and stuff, and other land-based predators. So they're put in check there.

"Usually when you have a predator in their natural habitat, Mother Nature takes care of the population. A species becomes invasive when you move it to an area where it doesn't have any natural predators.

"It's not mutation. They're just growing larger because they have lots of food and they live longer, maybe, than normally."

In other words, with nothing to fear and plenty of bugs and flying insects to eat, some coqui frogs are heftier simply because they've been pigging out.

Meanwhile, experts have yet to determine whether the 50 percent bigger frogs are 50 percent louder as well, Saneishi said.