Conservation Status of Tree Snail Species in the Genus Partulina (Achatinellinae) on the Island of Hawai'i: A Modern and Historical Perspective

摘要

The Hawaiian tree snail genus Partulina, from Maui, Moloka'i,Uina'i, O'ahu, and the island of Hawai'i, is the sister-genus of the endangeredAchatinella, found only on the island of O'ahu. Life histories of species in thetwo genera are similar, and undoubtedly the Partulina species have been asseverely impacted by the collective effects of habitat destruction and introducedpredators as have those of the genus Achatinella. Three species of Partulinahave been described from the island of Hawai'i: Partulina physa, P. confusa,and P. horneri. Until 1992, there were no recorded sightings of these species formore than 46 yr. Historically, Partulina spp. were recorded at various locationsin almost all districts of the island of Hawai'i, including North and SouthKona, North and South Kohala, Hamakua, North and South Hilo, and Puna.Partulina physa was found nearly islandwide, whereas P. confusa and P. horneriwere mostly located in the Hamakua and Kohala Districts. Partulina confusaand P. horneri were not found in the current surveys. Extensive field surveys onthe island of Hawai'i between May 1995 and December 1997 resulted in thelocation of only one population of Partulina physa, inhabiting a narrow rangein the Kohala Mountains. The shell length and reproductive state were recordedfor 82 individuals of P. physa from that population. Mean adult shelllength was 15.08 mm. Habitat loss, much of which occurred between 200 and100 yr ago, has likely been the greatest factor contributing to the decline of thePartulina spp. of the island of Hawai'i. Predation and shell collecting, andpossibly climatic changes and pathogens, have also contributed to the decline ofthe Partulina species on Hawai'i Island. A small captive population of P. physaat the University of Hawai'i at Manoa has suffered high juvenile mortality(78%).