Wainuia

Wainuia
Wainuia urnula
Scientific classification
Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
Order: Stylommatophora
Superfamily: Rhytidoidea
Family: Rhytididae
Subfamily: Rhytidinae
Genus: Wainuia
Powell, 1930
Type species
Helix urnula

Wainuia is a genus of air-breathing predatory land snails, terrestrial pulmonate gastropod molluscs in the family Rhytididae.[1] Species in this genus are endemic to New Zealand, and are carnivorous, primarily predating on amphipods and earthworms. Many members of the genus are at risk of extinction, including W. clarki, which has been impacted due to predation by introduced species including rats, song thrushes and hedgehogs, as well as drying forest floor habitats.

Description

In the original description, Powell described the genus as below:

The radula has a relatively small number of teeth per row and the outermost lateral is only half the size of the second lateral from the margin, which is the largest; the remaining teeth diminish in size to the centre. These features are also common to Rhytida but not to Paryphanta in which a much greater number of teeth are present per row and these differ in gradually increasing in size from the margin and decreasing again towards the centre. The radula of Wainuia differs from that of Rhytida in all the teeth being long, slender and similarly shaped...the shell of Wainuia is characterized by being thin, black, malleated and composed almost entirely of conchin.[2]

The width of the shell of Wainuia ranges between 21–38 mm (0.83–1.50 in).[3] The genus has an olive-brown periostracum, a weakly calcareous shell primarily made of conchin, tha has radially-oriented diagonal cords on the periphery that extend on the upper shell surface towards the suture.[4]

Members of the genus are difficult to distinguish based on shell patterns, and are typically identified by their size differences and geographic distributions.[3] Wainuia can be distinguished from Rhytida due to members of Wainuia having a thin, very darkly-coloured shell.[4]

Taxonomy

The genus was first described by A. W. B. Powell in 1930, who noted two species had features similar to but distinct from Rhytida and Paryphanta: W. urnula (formerly known as Helix urnula or Paryphanta urnula) and W. edwardi (formerly Paryphanta edwardi).[2] Powell named the genus after the Lower Hutt suburb Wainuiomata.[5] In 1977, Frank Climo described Wainuia as a subgenus of Rhytida,[4][6] which was not accepted by Powell, who continued to describe Wainuia as a distinct genus in 1979.[3] Powell's interpretation was supported by phylogenetic analysis undertaken in 2002.[3]

In 1936, Powell described a new species, W. clarki,[7] and by the subspecies W. urnula nasuta and W. fallai in 1946.[8] In 2002, phylogenetic analysis led to W. urnula nasuta being raised to species level, and W. fallai becoming synonymised with W. edwardi.[3]

Ecology

Species of the genus Wainuia are carnivorous.[3] The preferred prey of W. edwardi, W. clarki and W. urnula are amphipods, especially Parorchestia tenuis, while W. nasuta has a more varied diet that includes both earthworms and amphipods.[3][9] Wainuia have eggs with a calcareous surface which lacks cuticle.[10]

W. clarki populations are at-risk due to predation by Norway rats, ship rats, song thrushes and hedgehogs, as well as forest floor habitats becoming drier.[11] Wainuia "Mount Oxford", known from Canterbury, may represent an undescribed species within Wainuia.[11]

Distribution and habitat

The genus is endemic to New Zealand.[12][13]

Conservation status

Under the New Zealand Threat Classification System, one species in the genus is listed as "Nationally Critical", two as "Declining", and one as "Not Threatened".[14]

Species

Species within the genus Wainuia include:[1]

Species brought into synonymy
  • Wainuia fallai A. W. B. Powell, 1946: synonym of Wainuia edwardi (Suter, 1899)
  • Holotype of W. clarki
  • W. edwardi
  • Holotype of W. edwardi
  • Holotype of Wainuia nasuta
  • Shell of W. nasuta in the wild
  • W. urnula
  • Overturned W. urnula

References

  1. ^ a b Wainuia A. W. B. Powell, 1930. Retrieved through: World Register of Marine Species on 27 November 2025.
  2. ^ a b Powell, A. W. B. (1930). "The Paryphantidae of New Zealand: their Hypothetical Ancestry, with descriptions of New Species and a New Genus". Records of the Auckland Institute and Museum. 1: 17–56. ISSN 0067-0464. JSTOR 42905933. Wikidata Q58676532.
  3. ^ a b c d e f g Efford, Murray; Howitt, Robyn; Gleeson, Dianne (September 2002). "Phylogenetic relationships of Wainuia (Mollusca: Pulmonata)—biogeography and conservation implications". Journal of the Royal Society of New Zealand. 32 (3): 445–456. doi:10.1080/03014223.2002.9517703. ISSN 0303-6758. Wikidata Q29999582.
  4. ^ a b c Climo, F. M. (March 1977). "A new higher classification of New Zealand Rhytididae (Mollusca: Pulmonata)". Journal of the Royal Society of New Zealand. 7 (1): 59–65. doi:10.1080/03036758.1977.10419336. ISSN 0303-6758. Wikidata Q54555783.
  5. ^ Ridden, Johnathon (10 September 2024). "Aotearoa's shark-toothed and deadly carnivorous snails". Canterbury Museum. Retrieved 27 November 2025.
  6. ^ Efford, Murray (December 1998). Distribution and status of native carnivorous land snails in the genera Wainuia and Rhytida (PDF) (Report). Science for Conservation. Vol. 101. Wellington, New Zealand: Department of Conservation. ISBN 0-478-21771-4.
  7. ^ Powell, A. W. B. (1936). "The Paryphantidae of New Zealand. III. Further New Species of Paryphanta and Wainuia". Records of the Auckland Institute and Museum. 2: 29–41. ISSN 0067-0464. JSTOR 42905966. Wikidata Q58676583.
  8. ^ Powell, A. W. B. (1946). "The Paryphantidae of New Zealand. No. V. Further New Species of Paryphanta, Wainuia and Rhytida". Records of the Auckland Institute and Museum. 3: 99–136. ISSN 0067-0464. JSTOR 42905998. Wikidata Q58676634.
  9. ^ Efford, Murry (February 2000). "Consumption of Amphipods by the New Zealand Land Snail Wainui Urnula (Pulmonata: Rhytididae)". Journal of Molluscan Studies. 66 (1): 45–52. doi:10.1093/mollus/66.1.45.
  10. ^ O'Connor, A. C. (1945). "Notes on the Eggs of New Zealand Paryphantidae, With Description of a New Subgenus". Transactions and Proceedings of the Royal Society of New Zealand. 75: 54–57. ISSN 1176-6166. Wikidata Q89182837.
  11. ^ a b Walker, Kath; Walton, Kerry; Edwards, Eric; Hitchmough, Rod; Payton, Ian; Barker, Gary; Michel, Pascale (February 2024). "Conservation status of New Zealand indigenous terrestrial Gastropoda (slugs and snails) Part 3. Rhytididae (carnivorous snails), 2022" (PDF). New Zealand Threat Classification Series. 42: 1–32. ISSN 2324-1713. Wikidata Q124748983.
  12. ^ "Wainuia". New Zealand Organisms Register. Retrieved 27 November 2025.
  13. ^ Spencer, H.G.; Marshall, B.A.; Willan, R.C. (2009). "Checklist of New Zealand living Mollusca". In Gordon, Dennis P. (ed.). New Zealand inventory of biodiversity. Volume one. Kingdom Animalia: Radiata, Lophotrochozoa, Deuterostomia. Christchurch: Canterbury University Press. p. 196–219. ISBN 978-1-877257-72-8.
  14. ^ "Wainuia". New Zealand Threat Classification System. Retrieved 27 November 2025.
  15. ^ "Wainuia clarki Powell, 1936". Global Biodiversity Information Facility. Retrieved 27 November 2025.
  16. ^ "Wainuia edwardi (Suter, 1899)". Global Biodiversity Information Facility. Retrieved 27 November 2025.
  17. ^ "Wainuia nasuta Powell, 1946". Global Biodiversity Information Facility. Retrieved 27 November 2025.
  18. ^ Brook, Fred J.; Ablett, Jonathan D. (14 November 2019). "Type material of land snails (Mollusca: Gastropoda) described from New Zealand by taxonomists in Europe and North America between 1830 and 1934, and the history of research on the New Zealand land snail fauna from 1824 to 1917". Zootaxa. 4697 (1): 1–117. doi:10.11646/ZOOTAXA.4697.1.1. ISSN 1175-5334. PMID 32230000. Wikidata Q86973765.
  19. ^ "Wainuia urnula (Reeve, 1854)". Global Biodiversity Information Facility. Retrieved 27 November 2025.

Further reading

  • Powell, A.W.B. (1979). New Zealand Mollusca: Marine, Land and Freshwater Shells. Auckland: Collins. ISBN 0002169061.
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