Powelliphanta

{{Short description|Genus of gastropods}} {{Use New Zealand English|date=July 2024}} {{Automatic taxobox | image = Powelliphanta hochstetteri bicolor shell.jpg | image_caption = Shell of ''Powelliphanta hochstetteri bicolor'' | taxon = Powelliphanta | authority = O'Connor, 1945<ref name="O'Connor">O'Connor A. C. (1945). [http://rsnz.natlib.govt.nz/volume/rsnz_75/rsnz_75_01_001590.html "Notes on the Eggs of New Zealand Paryphantidae, With Description of a New Subgenus."] ''Transactions of the Royal Society of New Zealand'' '''5''': 54–57.</ref> | subdivision_ranks = '''Species''' | subdivision = See text. }}

'''''Powelliphanta''''' is a genus of large, air-breathing land snails, pulmonate gastropods in the family Rhytididae, found only in New Zealand. They are carnivorous, eating invertebrates, mostly native earthworms. Often restricted to very small areas of moist forest, they are prey to introduced mammalian predators, and many species are threatened or endangered.

== Taxonomy == ''Powelliphanta'' was originally described by A. C. O'Connor in 1945 as a subgenus of the kauri snails, ''Paryphanta.'' They were named "in recognition of the great service rendered to the study of the family by Mr A. W. B. Powell", and from their similarity to ''Paryphanta''.<ref name="O'Connor" /> [[File:Powelliphanta lignaria johnstoni DOC 2003.jpg|thumb|''Powelliphanta lignaria johnstoni'', Mōkihinui River |left|300x300px]] [[File:Powelliphanta marchanti DOC 1986.jpg|left|thumb|300x300px|''Powelliphanta marchanti'']] [[File:Powelliphanta annectens DOC 2007.jpg|left|thumb|300x300px|''Powelliphanta annectens'']] [[File:Powelliphanta hochstetteri hochstetteri DOC 2009.jpg|left|300x300px|''Powelliphanta hochstetteri hochstetteri''|thumb]] {{cquote|Genus PARYPHANTA Albers, 1850.<br /> Sub-genus POWELLIPHANTA nov.

Shell generally, similar to ''Paryphanta'' Albers, but with the last whorl pulled in closer to the preceding whorl, and with a colour pattern of concentric or radially arranged bands, usually of alternating and contrasting colours. More important is the paucity of lime compared with conchin in the shell.

Egg always with cuticle, pale buff when laid.

Distribution: North Island of New Zealand, in and south of the Ruahine Range (possibly once as far north as East Cape) and South Island.

Type: ''Helix hochstetteri'' Pfeiffer, Mal. Bl., viii, 146, 1862 (see PI. 6, Figs. 5–8).

''Powelliphanta'' will include all New Zealand species previously included in ''Paryphanta'' except the type of that genus, ''P. busbyi'' (Gray, 1840) which is confined to the North Auckland Peninsula.}}

In 1977 Climo raised ''Powelliphanta'' to genus rank, retaining just two species in ''Paryphanta''.<ref>{{Cite journal|last=Climo|first=F.M.|date=1977|title=A new higher level classification of the New Zealand Rhytididae (Mollusca: Pulmonata)|journal=Journal of the Royal Society of New Zealand|volume=7|issue=1|pages=59–65|doi=10.1080/03036758.1977.10419336|doi-access=free}}</ref> There are at least 21 species and 51 subspecies within the genus.<ref>{{Cite web|url=http://www.doc.govt.nz/nature/native-animals/invertebrates/powelliphanta-snails/|title=Powelliphanta snail|website=Department of Conservation Te Papa Atawhai|publisher=New Zealand Department of Conservation|access-date=11 March 2016}}</ref> The relationship between the species is complex, and it has been suggested that the group ''Powelliphanta gilliesi-traversi-hochstetteri-rossiana-lignaria-superba'' forms a ring species.<ref>{{Cite journal|last=Climo|first=F.M.|date=1978|title=The ''Powelliphanta gilliesi-traversi-hochstetteri-rossiana-lignaria-superba'' ring species (Mollusca: Pulmonata)|journal=New Zealand Journal of Zoology|volume=5|issue=2|pages=289–294|doi=10.1080/03014223.1978.10428318}}</ref>

==Distribution== Powelliphanta are endemic to New Zealand, ranging in the North Island from Lake Waikaremoana to the Kāpiti Coast, and in the South Island from the Marlborough Sounds to Fiordland and Southland.<ref name=":2">{{Cite web|url=http://www.doc.govt.nz/Documents/about-doc/concessions-and-permits/conservation-revealed/nz-land-snails-lowres.pdf|title=New Zealand Land Snails|date=2006|website=RD&I Wellington|publisher=Department of Conservation|access-date=11 March 2016|archive-date=27 June 2016|archive-url=https://web.archive.org/web/20160627120317/http://www.doc.govt.nz/documents/about-doc/concessions-and-permits/conservation-revealed/nz-land-snails-lowres.pdf|url-status=dead}}</ref> Their greatest diversity is in the mountains of northwest Nelson and north Westland. Some species have an extremely restricted distribution, such as ''Powelliphanta gilliesi brunnea'', which is only found in a {{convert|1|ha}} remnant of coastal forest.<ref name=":0">{{Cite book|title=The Natural World of New Zealand|last=Hutching|first=Gerard|publisher=Reader's Digest|year=1998|isbn=978-0-86449-261-6|location=Auckland|pages=315}}</ref>

==Habitat== These snails live mostly in moist native forest. Some live in lowland forest, such as ''P. traversi traversi'', which is nationally endangered and has its own 10 ha reserve of kahikatea forest and raupo swamp near Levin. Other species live in upland forest, or even under tussock grasses above the treeline. Several species only inhabit forests on limestone soils; they require calcium to build their shells and eggs, and this is obtained from eating invertebrates (including other snails) which have taken up calcium from the limestone environment.<ref name=":0" /> ''Powelliphanta'' require a moist environment because, unlike other land snails, they cannot seal off their shells with a protective mucous membrane.<ref name=":0" />

==Description== [[File:Powelliphanta traversi traversi Papaitonga.jpg|thumb|''Powelliphanta traversi traversi'' at Lake Papaitonga]] The largest species, ''Powelliphanta superba prouseorum,'' has a shell up to {{convert|9|cm}} across and can weigh {{convert|90|g}}.<ref>{{Cite journal|last=Judd|first=Warren|date=July–September 1990|title=Slow, slimy and surprising!|url=http://www.nzgeographic.co.nz/archives/issue-007/slow-slimy-and-surprising|journal=New Zealand Geographic|issue=7|pages=84–110|access-date=11 March 2016}}</ref> The striking delicately patterned shells of ''Powelliphanta'' come in an array of shades, from brown or red to yellow or black. The structure of these shells is very delicate, with a very thin layer of calcium carbonate, covered by a thicker chitinous outer layer. These snails need moist surroundings, otherwise the outer layer (periostracum) dries, shrinks and cracks; this sometimes happens in museum shells of this genus which have been stored dry.

==Life habits== {{External media | align = | width = 185px | video1 = [https://www.youtube.com/watch?v=5xNxQfVNVR8 Snail Attack] (''Powelliphanta'' feeding) }}''Powelliphanta'' are carnivorous, eating mostly earthworms or slugs. They are nocturnal, and during the day live buried under leaf litter and logs. ''Powelliphanta'' uses a rudimentary radula to devour their prey: a tongue-like belt of teeth, which scrapes chunks of flesh into the oesophagus. Far from being swallowed whole, prey are subjected to prolonged radulation.

''Powelliphanta'' can live for 20 years or more, and are slow to mature, reaching sexual maturity around 5–6 years of age.<ref name=":0" /> They are hermaphrodites, having both male and female sex organs. They lay 5 to 10 large (bean-sized) eggs a year, which have a thin pink calcium carbonate shell, like a tiny bird's egg.<ref>{{Cite web|url=http://www.TeAra.govt.nz/en/snails-and-slugs/page-2|title=Snails and slugs – Flax snails, giant snails and veined slugs|last=Ryan|first=Paddy|date=13 July 2012|website=Te Ara – the Encyclopedia of New Zealand|access-date=11 March 2016}}</ref> Eggs take 2–6 months to hatch in lowland species, 12–14 months for high-altitude species.<ref name=":1">{{Cite news|url=http://www.stuff.co.nz/nelson-mail/lifestyle-entertainment/weekend/2882481/Its-so-hard-being-a-snail|title=It's so hard being a snail|last=Collett|first=Geoff|date=19 September 2009|work=Nelson Mail|access-date=11 March 2016}}</ref>

==Fossil record== Originating more than 235 million years on the supercontinent Gondwana, these snails have been isolated in New Zealand since it separated from Australia about 80 million years ago, and have evolved into numerous distinct species.<ref name=":0" />

==Conservation status== [[File:Possum predated Powelliphanta traversi DOC 1994.jpg|left|thumb|Possum-preyed ''Powelliphanta traversi'' snail shells.]] Most of these snails are under serious threat or even in danger of extinction. Their main natural predator is the weka,<ref name=":1" /> but they have no defences against introduced mammalian predators, such as brushtail possums (''Trichosurus vulpecula''), pigs, hedgehogs,<ref>{{cite web|url=http://www.landcareresearch.co.nz/news/release.asp?Ne_ID=86|title=Hedgehogs pose prickly problem for native fauna|date=17 September 2003|publisher=Landcare Research media release|access-date=6 December 2011|archive-date=1 October 2003|archive-url=https://web.archive.org/web/20031001170723/http://www.landcareresearch.co.nz/news/release.asp?Ne_ID=86|url-status=dead}}</ref> and rats. Possums have been shown to eat up to 60 snails in one night.{{Citation needed|date = March 2016|Broken link to video =}} Habitat modification and trampling by introduced animals like goats, deer, and cows is also a threat.<ref name=":2" />

Controlling predatory mammals is now critical to the survival of ''Powelliphanta'', and many recovery plans are being undertaken by the Department of Conservation. After aerial application of 1080 poison, ''P. "Anatoki Range"'' numbers increased threefold at sites in Kahurangi National Park, with large numbers of juveniles present. Prior to applying 1080, there were 54 snails found on a 500 sq grid.{{clarify|no unit of measurement given - 500 sq what?|date=November 2016}} One year after the 1080 drop, 147 snails were found on the same plot.{{Citation needed|date = March 2016}} Between 1994 and 2010, a series of three aerial 1080 operations over 3430 ha of the Ruahine Forest Park resulted in significant increases in ''Powelliphanta marchanti''.<ref>{{Cite web|url = http://www.doc.govt.nz/news/media-releases/2010/giant-snails-the-winners/|title = Giant snails the winners|date = 26 October 2010|website = Department of Conservation Te Papa Atawhai|publisher = New Zealand Department of Conservation|access-date = 11 March 2016}}</ref> The subspecies ''Powelliphanta gilliesi brunnea'' and ''Powelliphanta traversi otakia'' are the most threatened. The IUCN Red List states for ''Powelliphanta marchantii'' a lower risk, near threatened.

It is illegal since 1982 to collect shells of ''Powelliphanta''; collecting live animals for their shells may have made some species rarer, but some species also need to feed on discarded shells to recycle their calcium lining.<ref name=":2" />

==Cultural relevance== A ''Powelliphanta'' illustrated by Dave Gunson appeared on a New Zealand 40-cent postage stamp, issued October 1997.<ref>{{Cite web|url=https://stamps.nzpost.co.nz/new-zealand/1997/creepy-crawlies|title=Creepy Crawlies|website=New Zealand Post Stamps|access-date=19 June 2016}}</ref>

==References== {{Reflist}} This article incorporates public domain text from O'Connor (1945).

==Further reading== * Walker, K. J. (2003) "Recovery plans for ''Powelliphanta'' land snails 2003–2013". Threatened Species Recovery Plan '''49'''. Wellington, New Zealand Department of Conservation. 208 pp. + 64 pl. ([http://www.doc.govt.nz/upload/documents/science-and-technical/TSRP49.pdf Pages 1–12], [http://www.doc.govt.nz/upload/documents/science-and-technical/TSRP49a.pdf 13–140], [http://www.doc.govt.nz/upload/documents/science-and-technical/TSRP49b.pdf 141–196], [http://www.doc.govt.nz/upload/documents/science-and-technical/TSRP49c.pdf 197–208].) * Meads, M. J., Walker, K. J., & Elliot, G. P. (1984) "Status, conservation, and management of the land snails of the genus ''Powelliphanta'' (Mollusca: Pulmonata)". ''New Zealand Journal of Zoology'' '''11''': 277–306. * Judd, Warren (1990). [http://www.nzgeographic.co.nz/archives/issue-007/slow-slimy-and-surprising "Slow, slimy and surprising!"] ''New Zealand Geographic'' (007, July–September): 84–110.

==External links== {{Wikispecies}} {{Commons category|Powelliphanta}} * ''Powelliphanta'' discussed on RadioNZ ''Critter of the Week'', [http://www.radionz.co.nz/national/programmes/afternoons/audio/201792840/critter-of-the-week-nicola-toki 11 March 2016] * [http://www.doc.govt.nz/nature/native-animals/invertebrates/powelliphanta-snails/ Department of Conservation information on ''Powelliphanta'']

Category:Powelliphanta Category:Rhytididae Category:Endemic fauna of New Zealand Category:Endemic molluscs of New Zealand