Abstract

During the Whitney South Sea Expedition of the American Museum of Natural History six specimens of a medium-sized gadfly petrel, Pterodroma sp., were collected at sea during 28–29 January 1927 near Mera Lava, Banks Islands, Vanuatu. Initially labelled as Pterodroma externa, they were referred toP. cervicalis, but of a smaller form, by R. A. Falla in 1976. In 1983 another specimen was found on the coast of northern New South Wales. This species, newly described and named here as Pterodroma occulta, is close toP. cervicalis but differs mainly in its smaller size, relatively longer tail and entirely dark grey exposed primaries ventrally. The latter character may assist identification at sea, though 2 of 21 P. cervicalis studied (9.5%) were similar. Its breeding places are still unreported, though presumed to be in northern Vanuatu. Both this new species and White-naped Petrels, P. cervicalis, evidently occur in eastern Australian seas.