Prosobonia cancellata, the Tuamotu sandpiper, is a small to medium-sized bird found on a small number of coral atolls in French Polynesia. It is currently endangered with probably about 1200-1300 surviving individuals in 2003, mostly on the two islands of Tenararo and Morane (Pierce & Blanvillain, 2004). Zusi & Jehl (1970) included Prosobonia in the subfamily Tringinae, which also includes the Tringa sandpipers, Numenius (curlews) and Limosa (godwits). Prosobonia differs from these genera in living higher up on the shoreline, including the atoll forest, feeding on small invertebrates gleaned among leaf litter and off trees. They also seem to eat a reasonable amount of plant material such as seeds.
Other Prosobonia species were once found on a number of tropical Polynesian islands, while P. cancellata itself was previously more widespread with a range extending to Kiritimati (Christmas Island) in Kiribati. Some authors have regarded the Tuamotu and Kiritimati populations as separate subspecies or species, but Zusi and Jehl (1970) pointed out that the only known specimen from Kiritimati (unfortunately no longer available) probably lay within the known range of variation for Tuamotu specimens. Prosobonia leucoptera was found on Tahiti and Moorea (again, some authors have regarded the two populations as separate species) while undescribed subfossils have been found on Henderson, Marquesas and Cook Islands. Prosobonia cancellata has also been placed in a separate genus, Aechmorhynchus, from P. leucoptera, but again Zusi & Jehl established that significant differences between the two species were few except for coloration pattern (P. cancellata has barred plumage, while P. leucoptera was plainer) so there can be little doubt of their close relationship relative to other taxa.
Pierce, R. J., & C. Blanvillain. 2004. Current status of the endangered Tuamotu sandpiper or titi Prosobonia cancellata and recommended actions for its recovery. Wader Study Group Bulletin 105: 93-100.
Zusi, R. L., & J. R. Jehl Jr. 1970. The systematic relationships of Aechmorhynchus, Prosobonia, and Phegornis (Charadriiformes; Charadrii). Auk 87: 760-780.