Powelliphanta

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Powelliphanta
Powelliphanta hochstetteri bicolor shell.jpg
Shell of Powelliphanta hochstetteri bicolor
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
Order: Stylommatophora
Family: Rhytididae
Subfamily: Rhytidinae
Genus: Powelliphanta
O'Connor, 1945 [1]
Species

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.

Contents

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. [1]

Powelliphanta lignaria johnstoni, Mokihinui River Powelliphanta lignaria johnstoni DOC 2003.jpg
Powelliphanta lignaria johnstoni , Mōkihinui River
Powelliphanta marchanti Powelliphanta marchanti DOC 1986.jpg
Powelliphanta marchanti
Powelliphanta annectens Powelliphanta annectens DOC 2007.jpg
Powelliphanta annectens
Powelliphanta hochstetteri hochstetteri Powelliphanta hochstetteri hochstetteri DOC 2009.jpg
Powelliphanta hochstetteri hochstetteri

Genus PARYPHANTA Albers, 1850.

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. [2] There are at least 21 species and 51 subspecies within the genus. [3] 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. [4]

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. [5] 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 1 hectare (2.5 acres) remnant of coastal forest. [6]

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. [6] Powelliphanta require a moist environment because, unlike other land snails, they cannot seal off their shells with a protective mucous membrane. [6]

Description

Powelliphanta traversi traversi at Lake Papaitonga Powelliphanta traversi traversi Papaitonga.jpg
Powelliphanta traversi traversi at Lake Papaitonga

The largest species, Powelliphanta superba prouseorum, has a shell up to 9 centimetres (3.5 in) across and can weigh 90 grams (3.2 oz). [7] 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 videos
Nuvola apps kaboodle.svg 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. [6] 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. [8] Eggs take 2–6 months to hatch in lowland species, 12–14 months for high-altitude species. [9]

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. [6]

Conservation status

Possum-preyed Powelliphanta traversi snail shells. Possum predated Powelliphanta traversi DOC 1994.jpg
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, [9] but they have no defences against introduced mammalian predators, such as brushtail possums (Trichosurus vulpecula), pigs, hedgehogs, [10] and rats. Possums have been shown to eat up to 60 snails in one night.[ citation needed ] Habitat modification and trampling by introduced animals like goats, deer, and cows is also a threat. [5]

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.[ clarification needed ] One year after the 1080 drop, 147 snails were found on the same plot.[ citation needed ] 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 . [11] 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. [5]

Species

Species within the genus Powelliphanta include:

Undescribed species

Cultural relevance

A Powelliphanta illustrated by Dave Gunson appeared on a New Zealand 40-cent postage stamp, issued October 1997. [12]

Related Research Articles

<i>Paryphanta</i> Genus of gastropods

Paryphanta is a genus of land snails in the family Rhytididae. Species from New Zealand are known commonly as kauri snails. They are closely related and similar to snails in the genus Powelliphanta, which was formerly included within Paryphanta.

<span class="mw-page-title-main">Rhytididae</span> Family of gastropods

Rhytididae is a taxonomic family of medium-sized predatory air-breathing land snails, carnivorous terrestrial pulmonate gastropod molluscs in the superfamily Rhytidoidea.

<i>Schizoglossa</i> Genus of gastropods

Schizoglossa, common name the Pāua slugs, is a genus of medium-sized to large predatory, air-breathing, land slugs, carnivorous terrestrial pulmonate gastropod molluscs in the family Rhytididae. They are currently classified by the New Zealand Department of Conservation as Nationally Vulnerable.

<i>Wainuia</i> Genus of gastropods

Wainuia is a genus of air-breathing predatory land snails, terrestrial pulmonate gastropod molluscs in the family Rhytididae. Species in this genus occur in New Zealand.

<i>Paryphanta busbyi</i> Species of gastropod

Paryphanta busbyi is a species of large predatory land snail, a terrestrial pulmonate gastropod mollusc in the family Rhytididae.

<i>Powelliphanta superba</i> Species of gastropod

Powelliphanta superba is a species of large, carnivorous land snail in the family Rhytididae, which is endemic to the South Island of New Zealand. Five subspecies are recognised, all of which are classified by the New Zealand Department of Conservation as being Nationally Endangered.

Powelliphanta fiordlandica, one of the amber snails, is a species of large, carnivorous land snail, a terrestrial pulmonate gastropod mollusc in the family Rhytididae.

<i>Powelliphanta annectens</i> Species of gastropod

Powelliphanta annectens is one of the amber snails, an air-breathing land snail, a terrestrial gastropod mollusc in the family Rhytididae. It is a protected species with very limited distribution.

<i>Powelliphanta augusta</i> Species of gastropod

Powelliphanta augusta or the Mount Augustus snail, previously provisionally known as Powelliphanta "Augustus", is a species of large, carnivorous land snail, a terrestrial pulmonate gastropod mollusc in the family Rhytididae. Naturally occurring only on Mount Augustus near Westport on New Zealand's South Island, their entire habitat was destroyed by coal mining. The world population was taken into captivity, in theory until their habitat was restored and they could be released. The mining company concerned went bankrupt and habitat restoration has been unsuccessful, so the species' future is uncertain.

<i>Powelliphanta rossiana</i> Species of gastropod

Powelliphanta rossiana, known as Ross' land snail, is a species of large, carnivorous land snail, a terrestrial pulmonate gastropod mollusc in the family Rhytididae. This species is endemic to the South Island of New Zealand. Subspecies include:

<i>Powelliphanta patrickensis</i> Species of gastropod

Powelliphanta patrickensis is a species of large, carnivorous land snail, a terrestrial pulmonate gastropod mollusc in the family Rhytididae. This species is endemic to the South Island of New Zealand. Formerly, it was considered as a subspecies of Powelliphanta rossiana.

<i>Powelliphanta gilliesi</i> Species of gastropod

Powelliphanta gilliesi, one of the "amber snails", is a species of large, carnivorous land snail, a terrestrial pulmonate gastropod mollusc in the family Rhytididae.

<i>Powelliphanta hochstetteri</i> Species of land snail

Powelliphanta hochstetteri, known as one of the amber snails, is a species of large, carnivorous land snail, a terrestrial pulmonate gastropod mollusc in the family Rhytididae.

<i>Powelliphanta hochstetteri anatokiensis</i> Subspecies of gastropod

Powelliphanta hochstetteri anatokiensis, known as one of the amber snails, is a subspecies of large, carnivorous land snail, a terrestrial pulmonate gastropod mollusc in the family Rhytididae. It is found in New Zealand.

<i>Powelliphanta hochstetteri bicolor</i> Subspecies of gastropod

Powelliphanta hochstetteri bicolor, known as one of the amber snails, is a subspecies of large, carnivorous land snail, a terrestrial pulmonate gastropod mollusc in the family Rhytididae.

<i>Powelliphanta hochstetteri consobrina</i> Subspecies of gastropod

Powelliphanta hochstetteri consobrina, known as one of the amber snails, is a subspecies of large, carnivorous land snail, a terrestrial pulmonate gastropod mollusc in the family Rhytididae.

<i>Powelliphanta hochstetteri obscura</i> Subspecies of gastropod

Powelliphanta hochstetteri obscura, known as one of the amber snails, is a subspecies of large, carnivorous land snail, a terrestrial pulmonate gastropod mollusc in the family Rhytididae.

<i>Powelliphanta traversi</i> Species of mollusc

Powelliphanta traversi, known as Travers' land snail, is a species of large, carnivorous land snail, a terrestrial pulmonate gastropod mollusc in the family Rhytididae. This species is endemic to the North Island of New Zealand between Wellington and Lake Waikaremoana.

<i>Powelliphanta lignaria</i> Species of gastropod

Powelliphanta lignaria, known as one of the amber snails, is a species of large, carnivorous land snail, a terrestrial pulmonate gastropod mollusc in the family Rhytididae. The eggs of P. lignaria are oval and seldom constant in dimensions 10 × 8.25, 9 × 7.75, 9 × 8, 8.75 × 7.75 mm.

References

  1. 1 2 O'Connor A. C. (1945). "Notes on the Eggs of New Zealand Paryphantidae, With Description of a New Subgenus." Transactions of the Royal Society of New Zealand5: 54–57.
  2. ↑ Climo, F.M. (1977). "A new higher level classification of the New Zealand Rhytididae (Mollusca: Pulmonata)". Journal of the Royal Society of New Zealand. 7 (1): 59–65. doi: 10.1080/03036758.1977.10419336 .
  3. ↑ "Powelliphanta snail". Department of Conservation Te Papa Atawhai. New Zealand Department of Conservation. Retrieved 11 March 2016.
  4. ↑ Climo, F.M. (1978). "The Powelliphanta gilliesi-traversi-hochstetteri-rossiana-lignaria-superba ring species (Mollusca: Pulmonata)". New Zealand Journal of Zoology. 5 (2): 289–294. doi:10.1080/03014223.1978.10428318.
  5. 1 2 3 "New Zealand Land Snails" (PDF). RD&I Wellington. Department of Conservation. 2006. Archived from the original (PDF) on 27 June 2016. Retrieved 11 March 2016.
  6. 1 2 3 4 5 Hutching, Gerard (1998). The Natural World of New Zealand. Auckland: Reader's Digest. p. 315. ISBN   978-0-86449-261-6.
  7. ↑ Judd, Warren (July–September 1990). "Slow, slimy and surprising!". New Zealand Geographic (7): 84–110. Retrieved 11 March 2016.
  8. ↑ Ryan, Paddy (13 July 2012). "Snails and slugs – Flax snails, giant snails and veined slugs". Te Ara – the Encyclopedia of New Zealand. Retrieved 11 March 2016.
  9. 1 2 Collett, Geoff (19 September 2009). "It's so hard being a snail". Nelson Mail. Retrieved 11 March 2016.
  10. ↑ "Hedgehogs pose prickly problem for native fauna". Landcare Research media release. 17 September 2003. Archived from the original on 1 October 2003. Retrieved 6 December 2011.
  11. ↑ "Giant snails the winners". Department of Conservation Te Papa Atawhai. New Zealand Department of Conservation. 26 October 2010. Retrieved 11 March 2016.
  12. ↑ "Creepy Crawlies". New Zealand Post Stamps. Retrieved 19 June 2016.

This article incorporates public domain text from O'Connor (1945).

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