Fregetta comprises black-bellied and white-bellied storm-petrels.
White-bellied form of black-bellied storm-petrel thought present in South Atlantic.
Nuclear and mitochondrial genes highlight this taxon does exist on Gough Island and in the Tristan group.
Two taxa of white-bellied storm-petrel also occur in the Atlantic Tristan group.
Research is required to determine how these forms segregate in sympatry.