It's hard to figure how olingos and onlinguitos were confused for each other.
"How is it different? In almost every way that you can look at it," Helgen said.
Olinguitos are smaller, have shorter tails, a rounder face, tinier ears and darker bushier fur, he said.
"It looks kind of like a fuzzball kind of like a cross between a teddy bear and a house cat," Helgen said.
It eats fruit and has one baby at a time. Helgen figures there are thousands of olinguitos in the mountainous forest, traveling through the trees at night which makes them hard to see.
While new species are found regularly, usually they are tiny things like insects and not mammals, the warm-blooded advanced class of animals that have hair, live births and mammary glands in females.
Outside experts said this discovery not merely renaming something, but a genuine new species -- with three new subspecies -- and a significant find, the type that hasn't happened for about 35 years.
"Most people believe there are no new species to discover, particularly of relatively large charismatic animals," said Case Western Reserve University anatomy professor Darin Croft. "This study demonstrates that this is clearly not the case."
The olinguito is the smallest member of the raccoon family of mammals.
The researchers only saw olinguitos in Ecuador and Colombia, but they said they could also be living in parts of Panama, Costa Rica, Venezuela, Brazil, Peru, and Guyana, based on their cloud forest habitat.
The olingo is also native to Central and South America.
The North Carolina museum is already selling olinguito stuffed animals for about $15. Proceeds will benefit habitat preservation for the creatures.