Hidden in plain sight: DNA sequencing of museum specimens confirms the occurrence of MacGillivray’s Prion (<i>Pachyptila macgillivrayi</i>) in Australia and New Zealand

Museum research collections provide a rich source of data on species distributions, particularly when they are assessed with modern genetic techniques. MacGillivray’s Prion (<i>Pachyptila macgillivrayi</i>) is a morphologically cryptic seabird (Family Procellariidae) that breeds on Saint Paul Island (southern Indian Ocean) and Gough Island (South Atlantic Ocean). Their extreme similarity to the closely related Broad-billed Prion (<i>P. vittata</i>) and Salvin’s Prion (<i>P. salvini</i>) means that little is known about their at-sea distribution. A recent geolocator-logger tracking study of MacGillivray’s Prions from the Saint Paul Island population revealed that about half the birds wintered in the Tasman Sea. As the species is not otherwise known from either Australia or New Zealand, we assessed study skins of ‘medium-to-large-billed’ beach-cast prions held by the Museum of New Zealand Te Papa Tongarewa and the South Australian Museum, to investigate whether any could be MacGillivray’s Prions. Sequencing of the mitochondrial cytochrome <i>b</i> locus and genotyping of 14 microsatellite loci from the selected museum specimens confirmed MacGillivray’s Prion to be among prions found on both Australian and New Zealand coasts. However, all five specimens of MacGillivray’s Prion found in the museum collections were genetically most similar to the more distant (and much larger) Gough Island population, and they all had bill measurements that matched the Gough Island population. We present information on bill characteristics that may aid identification of beach-cast or museum specimens of MacGillivray’s Prions, or selection of further specimens for genetic comparison with reference sequences.