Lord Howe flax snail

Lord Howe flax snail
Conservation status
	; Critically Endangered (IUCN 2.3)[1]
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
Subclass:	Heterobranchia
Order:	Stylommatophora
Family:	Bothriembryontidae
Subfamily:	Placostylinae
Genus:	Placostylus
Species:	P. bivaricosus
Binomial name
	Placostylus bivaricosus; (Gaskoin, 1855)
	P. bivaricosus is endemic to Lord Howe Island
Synonyms
	Bulimus (Eurytus) etheridgei Brazier, 1889 (junior synonym); Bulimus (Placostylus) cuniculinsulae Cox, 1872 (junior synonym); Bulimus bivaricosus Gaskoin, 1855 (original combination); Bulimus bivaricosus etheridgei Hedley, 1891 (junior synonym); Placostylus (Maoristylus) bivaricosus (Gaskoin, 1855); Placostylus bivaricosus belli Iredale, 1944 (junior synonym); Placostylus bivaricosus royi Iredale, 1944 (junior synonym); Placostylus cuniculinsulae (Cox, 1872) (junior synonym); Placostylus gizoensis Clench, 1941 (junior synonym);

The Lord Howe flax snail or the Lord Howe placostylus, scientific name Placostylus bivaricosus, is a species of large air-breathing land snail, a terrestrial pulmonate gastropod mollusc in the family Bothriembryontidae. [2]

Distribution

This large snail is found only on Lord Howe Island off the east coast of Australia. Its conservation status has declined from common to endangered since rats were accidentally introduced to this World Heritage island in 1918.

Subspecies

Subspecies of Placostylus bivaricosus include:

Placostylus bivaricosus bivaricosus (Gaskoin, 1855)[3]
Placostylus bivaricosus etheridgei (Hedley, 1891)[3] - extinct[4]
Placostylus bivaricosus cuniculinsulae (Cox, 1872)[3]
Placostylus bivaricosus solidus (Brazier in Etheridge, 1889)[5][3]

Description

The genus Placostylus is a group of large ground dwelling gastropods with a disjunct distribution in the South west Pacific from the Solomon Islands, Fiji, and New Caledonia, to Lord Howe Island and the northern extremity of New Zealand. The Lord Howe flax snail has a brown, pointed shell up to 7 cm long and 2 cm in diameter.

Conservation

Species decline

Historical accounts and fossil evidence indicate that the Lord Howe Island flax snail was formerly widespread and abundant on the island. The decline was first noted in the 1940s and the species is now listed as critically endangered.

The black rat is considered to be the major predator of this species and likely to be a significant threat to its survival. European blackbirds and song thrushes (self-introduced around 1950) are also thought to be predators of the snail.

Habitat clearing and modification and habitat disturbance, possibly herbicides and pesticides also add to the species decline.

Recovery

In 2001, a recovery plan was completed to protect and recover the Lord Howe Island flax snail in the wild. Actions include habitat and population surveys, community awareness raising and a captive-breeding program.

The Lord Howe Island Board, responsible for implementation of the recovery plan, has since constructed a rodent and bird proof enclosure for the project and the first generation of captive bred Lord Howe Island land snails has hatched.

Over a period of two years, schoolchildren will closely monitor the captive snail population and their eggs, and will then measure growth rates and survival rates of the juvenile snails.

Rodent control or eradication on the island is crucial for the long-term survival of this snail in the wild.

References

Ponder, W.F. (1996). "Placostylus bivaricosus". IUCN Red List of Threatened Species. 1996: e.T17447A7077965. doi:10.2305/IUCN.UK.1996.RLTS.T17447A7077965.en. Retrieved 18 November 2021.
MolluscaBase eds. (2021). MolluscaBase. Placostylus bivaricosus (Gaskoin, 1855). Accessed through: World Register of Marine Species at: http://www.marinespecies.org/aphia.php?p=taxdetails&id=1149983 on 2022-01-22
Ponder W. F., Colgan D. J., Gleeson D. M. & Sherley G. H. (2003). "Relationships of Placostylus from Lord Howe Island: an investigation using the mitochondrial cytochrome c oxidase 1 gene". Molluscan Research 23(2): 159-178. doi:10.1071/MR03001, PDF.
Ponder, W.F. (1996). "Placostylus bivaricosus ssp. etheridgei". IUCN Red List of Threatened Species. 1996: e.T17448A7078251. doi:10.2305/IUCN.UK.1996.RLTS.T17448A7078251.en. Retrieved 18 November 2021.
Etheridge, R. (31 December 1889). "The general zoology of Lord Howe Island; containing also an account of the collections made by the Australian Museum Collecting Party, Aug.–Sept., 1887" (PDF). Australian Museum Memoir. 2 (1): 1–42. doi:10.3853/j.0067-1967.2.1889.479. Retrieved 23 January 2019.

External links

 Data related to Placostylus bivaricosus at Wikispecies

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[iucn_status_18_November_2021-1] Ponder, W.F. (1996). "Placostylus bivaricosus". IUCN Red List of Threatened Species. 1996: e.T17447A7077965. doi:10.2305/IUCN.UK.1996.RLTS.T17447A7077965.en. Retrieved 18 November 2021.

[WoRMS-2] MolluscaBase eds. (2021). MolluscaBase. Placostylus bivaricosus (Gaskoin, 1855). Accessed through: World Register of Marine Species at: http://www.marinespecies.org/aphia.php?p=taxdetails&id=1149983 on 2022-01-22

[Ponder_2003-3] Ponder W. F., Colgan D. J., Gleeson D. M. & Sherley G. H. (2003). "Relationships of Placostylus from Lord Howe Island: an investigation using the mitochondrial cytochrome c oxidase 1 gene". Molluscan Research 23(2): 159-178. doi:10.1071/MR03001, PDF.

[4] Ponder, W.F. (1996). "Placostylus bivaricosus ssp. etheridgei". IUCN Red List of Threatened Species. 1996: e.T17448A7078251. doi:10.2305/IUCN.UK.1996.RLTS.T17448A7078251.en. Retrieved 18 November 2021.

[Etheridge1889-5] Etheridge, R. (31 December 1889). "The general zoology of Lord Howe Island; containing also an account of the collections made by the Australian Museum Collecting Party, Aug.–Sept., 1887" (PDF). Australian Museum Memoir. 2 (1): 1–42. doi:10.3853/j.0067-1967.2.1889.479. Retrieved 23 January 2019.