The hybrid was spotted spending most of its time alongside another melon-headed whale by scientists on a two-week tagging and monitoring effort.
He's believe to be the first example of cross-species lovin' between rough-toothed dolphins and melon-headed whales.
The hybrid had a typical melon-headed whale's dorsal fin shape and dorsal cape, but it was also blotchy in pigmentation and had a sloping forehead, more reminiscent of a rough-toothed dolphin.
About the discovery of a new species of dolphins, scientists have not yet spoken, because it is not known whether this is a new animal to create viable offspring.
While some news organizations have described the hybrid as a new species, research biologist Robin Baird says in order for that to happen other things need to occur, including more widespread hybridization.
It is also only the third confirmed instance of a wild-born hybrid between species in the Delphinidae family. And this is the first in the history of such a hybrid. This suggests that the hybrid was not treated as an outcast by the melon-headed whales, although it's unclear how other rough-toothed dolphins would react to it. Soon after, they were able to get DNA, which led them to the definitive conclusion that it was indeed a hybrid of the two species.
Baird told ABC News the hybrid animal was pictured with a single melon-headed whale both times they spotted it, which added to the mystery surrounding the unusual animal. "I always thought they were out there in the wild existing - it only makes sense", he said. But don't call it a "wholphin", they say. "And to know she has cousins out there in the ocean is an wonderful thing to know".
The hybrid, named Kekaimalu, still lives at the marine mammal park, where she helps teach children about genetics.
"If we were lucky enough to find the pair again, we would try to get a biopsy sample of the accompanying melon-headed whale, to see whether it might be the mother of the hybrid, as well as get underwater images of the hybrid to better assess morphological differences from the parent species", he said.
Hybrids can be the effect of a population drop in one species and an individual experiences difficulty in finding a mate.
The male "wholphin", which is believed to be close to adult age, was spotted swimming with dolphins near the island of Kauai past year, according to Dr Robin Baird, the marine biologist who headed the expedition.