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The animal, which had an unusual grey stripe down the length of its body, was discovered last Thursday.
An Otago Museum spokeswoman said footage had emerged of what appeared to be the same dolphin being moved away from the shore of Doctors Point by members of the public last Wednesday.
Department of Conservation biodiversity ranger Jim Fyfe said the dolphin, which was taken to the museum, was originally believed to be a common dolphin.
''The museum can take credit for recognising that this species was something different and unexpected.''
It was the southernmost known stranding of the vagrant striped dolphin, Stenella coeruleoalba, which was normally a widely-distributed warm water species, he said.
The dolphin was often seen in the Pacific, Indian and Atlantic Oceans.
High tides on Thursday meant Doc staff and local runaka representatives had to act quickly to retrieve the dolphin from the beach.
The male dolphin did not have any obvious external injuries which would explain its death.
Massey University marine biologist Dr Karen Stokin said the body would offer information about the species.
''It's an opportunity to add more information to the picture we have slowly been building over a number of years to better understand health, ecology and biology of this species.''
She would travel to Dunedin later this year to carry out a post-mortem helped by researchers from the University of Otago, local runaka and museum.