Wednesday, July 4, 2018

[Ornithology • 2018] Pelecanoides whenuahouensis • Analyses of Phenotypic Differentiations Among South Georgian Diving Petrel (Pelecanoides georgicus) Populations Reveal An Undescribed and Highly Endangered Species from New Zealand

Pelecanoides whenuahouensis 
Fischer, Debski, Miskelly, Bost, Fromant, Tennyson, Tessler, Cole, Hiscock, Taylor & Wittmer, 2018

Whenua Hou Diving Petrel  ||   DOI:  10.1371/journal.pone.0197766 

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’. 

S1 Fig. Lateral view of the holotype of Pelecanoides whenuahouensis  (NMNZ OR.21058) (Johannes H. Fischer).

The new species of diving petrel, named Whenua Hou Pelecanoides whenuahouensis, is already marked as critically endangered. File size: 13.5 MB Attribution: Jake Osborne

Pelecanoides whenuahouensis sp. nov.  

Etymology: P. whenuahouensis is named after the name of Codfish Island in the Māori language/Te Reo Māori: Whenua Hou (pronounced 'fɛnua 'hou, meaning ‘new land’). This island hosts the only extant colony of this species. This name was selected by the Ngāi Tahu, the Māori people who still hold a genealogical, cultural, and spiritual connection to both the island and this species, which they consider a taonga (treasure).

Common name: We propose the English common name ‘Whenua Hou Diving Petrel’.

Generic placement: P. whenuahouensis clearly belongs in Pelecanoides (family: Pelecanoididae, order: Procellariiformes) based on a combination of black and white plumage, short, paddle-like wings, short tail, small and compact build, and bill morphology (short, broad based bill with hooked tip, a paraseptal process in nostrils, and gular pouch).

Diagnosis: P. whenuahouensis differs from P. garnottii, through bill morphology/coloration (a shorter, slimmer bill, with much smaller nostrils, the presence of lavender blue on the lower mandible, and a less well-defined paraseptal process (but both species have the paraseptal process placed at approximately 50%) and a smaller overall size (resulting in shorter wings, tarsi, and a much lower bodyweight). P. whenuahouensis, however, does appear to have a longer tail than P. garnottii. Furthermore, P. whenuahouensis exhibits 1) a much larger extent of contrasting ear coverts, 2) continuous and pure white scapulars, 3) a limited (light grey) collar, 4) much paler (light grey) flanks and axillaries, and 5) white underwings including primaries. In addition, P. whenuahouensis can also be readily distinguished from P. garnottii based on vocalisations.

Distribution: All known study skins of P. whenuahouensis originate from either Dundas Island, Enderby Island (both Auckland Islands, New Zealand), or Codfish Island, New Zealand. P. whenuahouensis remains extant only on Codfish Island, where it breeds in a minute (0.018 km2) strip of coastal, sandy foredunes in Sealers Bay. The historic distribution of P. whenuahouensis in New Zealand likely encompassed the Otago Peninsula on the South Island, Mason’s Bay on Stewart Island, Enderby and Dundas Islands on the Auckland Islands and the Chatham Islands.

The offshore distribution of P. whenuahouensis remains unknown. Prey species found in two specimens indicate that P. whenuahouensis forages on the edge of the continental shelf during the breeding season. The only documented P. georgicus record for Australia (Bellambi Beach, New South Wales) likely pertained to P. whenuahouensis, based on the reported biometrics (most notably a tail length of 41 mm), indicating at least considerable vagrancy potential, and perhaps a larger offshore distribution than previously assumed, as recently demonstrated in P. u. urinatrix.

Fig 6. Study skins of Pelecanoides georgicus from different populations (Johannes H. Fischer). (A) Dorsal view. (B) Ventral view. (C) Lateral view. SAO = NMNZ OR.18421; origin: South Georgia, U.K., South Atlantic Ocean. SIO = NMNZ OR.24768; origin: Heard Island, Australia, South Indian Ocean. NZ = NMNZ OR.21631; origin: Dundas Island, Auckland Islands, New Zealand. Note differences in bill depth (NZ having the highest/deepest), collar extent (SIO having the largest), extent of contrasting scapulars (NZ having the largest), and contrasting white markings on secondaries (NZ having the largest) among others.

Here, we provide evidence of the distinctiveness of the Whenua Hou Diving Petrel (Pelecanoides whenuahouensis sp. nov.; previously part of the South Georgian Diving Petrel P. georgicus complex), which is a ‘Critically Endangered’ species. The conservation status of this species has remained “hidden” to global conservation interests due to its inclusion in a polytypic “species”. New Zealand, however, maintains a national threat classification system and therefore, the dire situation of P. whenuahouensis has been acknowledged within New Zealand. Consequently, we advocate the continuing use of national threat classification systems, as in cases like this, it has complemented the global threat classification system, by protecting taxa for which the taxonomy is still unclear. In addition, we urge taxonomists to focus new research on polytypic species that are likely to include threatened taxa, for conservation efforts depend on species being a clear and single ecological unit.

Johannes H. Fischer, Igor Debski, Colin M. Miskelly, Charles A. Bost, Aymeric Fromant, Alan J. D. Tennyson, Jake Tessler, Rosalind Cole, Johanna H. Hiscock, Graeme A. Taylor and Heiko U. Wittmer. 2018. Analyses of Phenotypic Differentiations Among South Georgian Diving Petrel (Pelecanoides georgicus) Populations Reveal An Undescribed and Highly Endangered Species from New Zealand. PLoS ONE. 13(6): e0197766.  DOI:  10.1371/journal.pone.0197766

New diving petrel critically endangered

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