The Polynesian sandpipers form the genus Prosobonia. They are small wading birds confined to remote Pacific islands of French Polynesia. Only one species is now extant, and it is rare and little known. This bird is sometimes separated in the genus Aechmorhynchus, restricting the genus to the extinct southern forms.
Taxonomy
The genus Prosobonia was introduced in 1850 by the French naturalist Charles Lucien Bonaparte with the Tahiti sandpiper, as the type species. Bonaparte did not explain the etymology of the genus name but it is probably from the Ancient Greek prosōpon meaning "mask" or "face".
The International Ornithologists' Union lists four species in the genus. Of these three have become extinct in historical times.
- Tuamotu sandpiper, P. parvirostris
- † Kiritimati sandpiper, P. cancellata
- † Tahiti sandpiper, P. leucoptera
- † Moorea sandpiper, P. ellisi
An additional species was described in 2020 from subfossil remains.
- † Henderson sandpiper P. sauli
Indeterminate species are also known from the Marquesas and the Cook Islands. subfossil remains of Prosobonia have been recovered but not yet named. The first of these was almost certainly more closely related to the Tahiti and Moorea populations than to the Tuamotu sandpiper, but the exact nature of their relationship is unlikely to be resolved anytime soon. It disappeared in the early-mid 1st millennium AD, probably not long after 300 AD.
The Ua Huka and Henderson forms can be assumed to have been closer to the living species. The latter, a distinct species with long legs and short wings, became extinct only about 1000 years after the Mangaia form, some time after 1200.
In 2020 a new extinct species, Prosobonia sauli, was described from specimens found on Henderson Island, part of the Pitcairn Islands. A genetic analysis found that the genus was sister to the clade containing Arenaria and Calidris.