Partula is a genus of air-breathing tropical land snails, terrestrial pulmonate gastropod mollusks in the family Partulidae.[1] [2]
Many species of Partula are known under the general common names "Polynesian tree snail" and "Moorean viviparous tree snail".[3] Partulids are distributed across 5000sqmi of Pacific Ocean islands, from the Society Islands to New Guinea.
Once used as decorative items in Polynesian ceremonial wear and jewelry, these small snails (averaging about one-half to three-quarters of an inch in length) gained the attention of science when Dr. Henry Crampton (along with Yoshio Kondo) spent 50 years studying and cataloging partulids, detailing their remarkable array of morphological elements, ecological niches, and behavioral aspects that illustrate adaptive radiation.[4] [5]
The partulids of the island of Tahiti act as an example of the possible deleterious effects of attempted biological control. After an infestation of the introduced giant African land snails (Achatina spp.), the carnivorous Florida rosy wolfsnail (Euglandina rosea) was introduced into Tahiti in an attempt to combat the African species.
Instead, the rosy wolfsnail hunted the nearly 76 species of Partula that were endemic to Tahiti and the nearby islands, causing all but 12 species to go extinct within a decade. Scientists were able to save 12 of these species prior to their becoming extinct.
Today, the Zoological Society of London runs the Partula Programme Consortium which maintains a captive-breeding programme in the United Kingdom, France, and the United States.[6]
As of the 2024-1 update released on June 27, the IUCN Red List of Threatened Species contains 73 Partula species. Of these, 32 are listed as extinct, 10 are extinct in the wild, 17 are critically endangered, 8 are endangered, 2 are vulnerable and only 4 species are least concern.[7]
Individuals are being reintroduced to Tahiti from captive breeding programmes since 2014.[8] [9] In April 2023, over 5,000 individual snails from zoos in the United States and the United Kingdom were released on Tahiti and Mo'orea.
Species within the genus Partula include:[5]
| Species | S | P | C | Notes |
|---|---|---|---|---|
| Partula affinis | CR | 1 | A single population persists on Tahiti Iti but reasonable numbers exist in captivity. | |
| Partula arguta | PE | 0 | The last captive individual died in 1994. | |
| Partula assimilis | CR | 1 | Threatened by habitat loss, though currently relatively free of predators. | |
| Partula atilis | EX | 0 | ||
| Partula auraniana | EN | 5 | Extirpated from its type locality in Aore Island but persists in the Torres Islands. | |
| Partula aurantia | EX | 0 | The last captive individual died in the 1980s. | |
| Partula auriculata | EX | 0 | Could not be located after 1991. Old shells were found in 1994. | |
| Partula bilineata | EX | 0 | Could not be located after 1993. | |
| Partula clara | CR | 20 | Has become much rarer but several populations persist. | |
| Partula clarkei | EX | 0 | Last captive individual died in 1996. | |
| Partula compressa | PE | 1 | One population photographed in 2004. | |
| Partula cootei | EX | 0 | Outcompeted by Partula hyalina. Old shells found in 2005. | |
| Partula cramptoni | CR | 1 | Extirpated from Rennell Island, though survives in Bellona Island. | |
| Partula crassilabris | EX | 0 | ||
| Partula cuneata | EX | 0 | Could not be located in the 1992 survey. | |
| Partula cytherea | PE | 1 | Isolated population on Mt. Marau confirmed in 2005. | |
| Partula dentifera | EX | 0 | Only dead shells could be found in the 1991 survey. | |
| Partula desolata | N/A | 0 | Fossil species. | |
| Partula diminuta | EX | 0 | Could not be located after 1980. | |
| Partula dolichostoma | EX | 0 | Could not be located after 1980. | |
| Partula dolorosa | EX | 0 | Could not be located after 1992. | |
| Partula emersoni | CR | 2 | Currently only known from a dead subadult in one location and a live one in another. | |
| Partula eremita | EX | 0 | Could not be located after 1980. | |
| Partula faba | EX | 0 | The last captive individual died in 2016. | |
| Partula flexuosa | LC | ? | Tolerant of current levels of disturbance and predators. | |
| Partula garrettii | EW | 0 | ||
| Partula gibba | EN | 4 | Persists in Guam, Sarigan, Pagan and Saipan. Extinct on Aguiguan. | |
| Partula grisea | LC | ? | All populations appear to be tolerant of threats. | |
| Partula guamensis | EX | 0 | 2005, 2006 and 2008 surveys found only 4 old, eroded shells. | |
| Partula hebe | EW | 0 | ||
| Partula hyalina | VU | 1-5 | Wild populations may be recovering. | |
| Partula incrassa | CR | 1 | All individuals are hybrids with Partula clara. | |
| Partula jackieburchi | PE | 1 | May survive on Mt. Aorai. | |
| Partula labrusca | EX | 0 | The last captive individual died in 2002. | |
| Partula laevigata | PE | 1 | One population may survive in central Tahiti. | |
| Partula lanceolata | EN | 3 | Endemic to Mago, Cicia and Naiau. | |
| Partula langfordi | EX | 0 | Not located in 1992. | |
| Partula leefei | CR | 1 | Survival confirmed from a single individual. | |
| Partula leptochila | EX | 0 | Could not be located after 1980. | |
| Partula levistriata | EX | 0 | Could not be located after 1980. | |
| Partula lirata | EN | 11 | Many populations are unstable and inviable in the long-term. | |
| Partula lugubris | EX | 0 | Could not be located in the 1990s. | |
| Partula lutaensis | N/A | ? | Endemic to Rota. Little is known about this species. | |
| Partula lutea | EX | 0 | Only species found in Bora Bora. Could not be located in 2006 or 2017. | |
| Partula magistri | EX | 0 | Only known from a single specimen. | |
| Partula makatea | N/A | 0 | Fossil species. | |
| Partula meyeri | PE | 1 | Only known from a single location. Not seen since its discovery in 2005. | |
| Partula micans | LC | ? | No major threats to this species are known. | |
| Partula mirabilis | EW | 0 | ||
| Partula mooreana | EW | 0 | ||
| Partula navigatoria | EW | 0 | ||
| Partula nodosa | EW | 0 | ||
| Partula obesa | CR | 2 | Endemic to Alofi and Futuna. Population declined severely in both islands. | |
| Partula otaheitana | EN | 5-10 | Survives in populations above 950m altitude and in one population on Tahiti Iti. | |
| Partula pacifica | VU | 6-10 | Endemic to nine islands. Eliminated from Espiritu Santo and Aore, the island of "Yatalo" remains unidentified and the other six islands have not been surveyed. | |
| Partula pearcekellyi | EX | 0 | Single valley endemic. A single shell was found in 1992. | |
| Partula planilabrum | EX | 0 | Could not be located in 1994. | |
| Partula producta | EX | 0 | Could not be located after 1980. | |
| Partula protracta | EX | 0 | Could not be located after 1980. | |
| Partula pyramis | EN | 4-5 | Type population is almost certainly extinct. Remaining populations have not been surveyed. | |
| Partula radiolata | EN | 1 | Only one population remains. Viable but vulnerable. | |
| Partula radiosa | EN | 1-2 | Little is known about this species. May already be extinct. | |
| Partula recluziana | N/A | ? | Little is known about this species. | |
| Partula remota | EX | 0 | Could not be located after 1980. | |
| Partula rosea | EW | 0 | ||
| Partula rufa | PE | 1 | Not located after 1936. | |
| Partula sagitta | EX | 0 | Could not be located after 1990. | |
| Partula salifana | EX | 0 | Dead shells were found in 1989. | |
| Partula similaris | LC | ? | Tolerant of habitat loss and free of predators. | |
| Partula suturalis | EW | 0 | 2/2 subspecies survive. | |
| Partula taeniata | CR | 2 | 3/4 subspecies survive. | |
| Partula tohiveana | EW | 0 | ||
| Partula tristis | EX | 0 | Could not be located after 1990. | |
| Partula turgida | EX | 0 | Last captive individual died in 1992. | |
| Partula umbilicata | EX | 0 | Could not be located after 1980. | |
| Partula vanikorensis | CR | 1 | Endemic to Vanikoro. | |
| Partula varia | EW | 0 |
The Partula that were collected for ex situ breeding include the following:[10]
Tahiti - P. affinis, P. clara, P. hyalina, P. nodosa, P. otaheitana
Moorea - P. aurantia, P. mirabilis, P. mooreana, P. suturalis, P. taeniata, P. tohiveana
Huahine - P. arguta, P. rosea, P. varia
Raiatea - P. faba, P. garrettii (P. tristis), P. hebe, P. navigatoria (P. dentifera), P. turgida
Marianas - P. gibba, P. langfordiP. garrettii and P. navigatoria were misidentified as the species in parentheses next to them.
The list of surviving species are as follows:
Tahiti - P. affinis, P. clara, P. hyalina, P. incrassa, P. nodosa, P. otaheitana
Moorea - P. mirabilis, P. mooreana, P. suturalis, P. taeniata, P. tohiveana
Raiatea - P. garrettii (P. tristis), P. hebe, P. meyeri, P. navigatoria (P. dentifera)
Marianas - P. gibba, P. langfordi, P. lutaensis, P. radiolata
Micronesia - P. emersoni, P. rufa
Fiji - P. leefei, P. lirata
Solomon Islands - P. cramptoni, P. micans
Papua New Guinea - P. auraniana, P. similaris
Cook Islands - P. assimilis
Phylogenetic analyses revealed that many of the Partula species are not monophyletic.[11] The resulting cladogram is shown below.
Partula species on Tahiti were usually found on the undersides of the leaves of Caladium and plantain, although in some valleys, they were frequently found on Dracaena and turmeric.
This article incorporates public domain text from the reference.[12]