Data from: Analyses of phenotypic differentiations among South Georgian Diving Petrel (Pelecanoides georgicus) populations reveal an undescribed and highly endangered species from New Zealand

Unresolved taxonomy of threatened species is problematic for conservation
as the field relies on species being distinct taxonomic units. Differences
in breeding habitat and results from a preliminary molecular analysis
indicated that the New Zealand population of the South Georgian Diving
Petrel (Pelecanoides georgicus) was a distinct, yet undescribed, species.
We measured 11 biometric characters and scored eight plumage characters in
143 live birds and 64 study skins originating from most populations of P.
georgicus, to assess their taxonomic relationships. We analysed
differences with principal component analyses (PCA), factorial ANOVAs, and
Kruskal-Wallis rank sum tests. Results show that individuals from New
Zealand differ significantly from P. georgicus from all other populations
as following: 1) longer wings, 2) longer outer tail feathers, 3) deeper
bills, 4) longer heads, 5) longer tarsi, 6) limited collar extent, 7)
greater extent of contrasting scapulars, 8) larger contrasting markings on
the secondaries, 9) paler ear coverts, 10) paler collars, and 11) paler
flanks. Furthermore, we used a species delimitation test with quantitative
phenotypic criteria; results reveal that the New Zealand population of P.
georgicus indeed merits species status. We hereby name this new species
Pelecanoides whenuahouensis sp. nov. Due to severe reductions in its range
and the very low number of remaining birds (~150 individuals limited to a
single breeding colony on Codfish Island/Whenua Hou) the species warrants
listing as ‘Critically Endangered’.