The dolphin with the confusing name - its only relationship to the southern right whale is that neither has a dorsal fin - makes its home in the waters of the subantarctic.
It was frequently seen off the shores of Kaikoura and the Northland coast, but had only been reported stranded on New Zealand beaches 18 times - the last one at Punakaiki, on the West Coast, in 2007, Te Papa's national whale stranding database said.
Department of Conservation marine ranger Jim Fyfe said it was only the second time one had washed up on an Otago beach.
The first was in 1988 at Taieri Mouth.
A science teacher visiting Kaka Point discovered the dead dolphin on the beach on Saturday and called Doc to report what the teacher thought might be a Hector's dolphin.
Doc staff visited the site to examine the animal and, after a bit of investigation, identified it as a female southern right whale dolphin.
It was 2.2m long and displayed some "scrapings" around its nose area, though it was difficult to tell if they contributed to its death or happened afterwards, he said.
The dolphin was removed from the beach on Monday and had been taken to the Otago Museum freezer to be stored until University of Otago marine scientists Liz Slooten and Steve Dawson performed a necropsy on it as part of their marine mammal course.
That would help increase knowledge of the dolphin and possibly shed some light on why it died, Mr Fyfe said.
