Ku-ring-gai Snails information sheet

Native snails occur in both urban and bushland habitats in the Ku-ring-gai municipality however few people would know they are present. Most species are tiny leaf litter dwellers belonging to the families Charopidae and Punctidae however some larger species belong to the families Strangesta 'Ku-ring-gai'(carnivorous snails),Parmavitrina 'Central Coast(semi slugs) Austrochloritis 'Sydney(red triangle slugs) and Camaenidae (Meridolum and Austrochloritis snails). Most of the native snail species in Ku-ring-gai are found in the surrounding municipalities, shires and cities of Lane Cove, Willoughby, Hornsby, Warringah, Pittwater, Ryde and Baulkham Hills however one large species of undescribed carnivorous snail – Strangesta Ku-ring-gai is endemic to Ku-ring-gai and Woollahra municipalities only and is endangered though at present unlisted. Another large species – the undescribed semi slug Parmavitrina 'Central Coast' – is known only from a single locality in Kuringai though it is more common north of the Hawkesbury River.

The following is a selection of species known to occur in Kuringai municipality that show varying levels of tolerance to habitat alteration and weed infestation。


Key to species vegetation habitat requirements and snail size:

# = Dry sclerophyll woodland and forest

* = Vine thicket and rainforest

. = tiny (< 4mm)

o = small (4 – 12mm)

O = large (> 12mm)

1.Those species that are most adaptable and widespread (ie they are found in most urban areas, parks and bushland with weed infestation) include the following –

Diphyoropa saturni (Charopidae) # .

Decoriropa lirata (Charopidae) # * .

Paralaoma caputspinulae (Punctidae) # .

Austrorhytida capillacea (Strangesta) # O

2.Species which show a moderate tolerance of habitat disturbance (ie they may live in bushy suburban gardens as well as in bushland) include –

Macrophallikaropa belli (Charopidae) # * .

Iotula microcosmos (Punctidae) # * .

Saladelos dulcis (Rhytididae) # * o

Triboniophorus graeffei (Athoracophoridae) # * O

Peloparion iridis (Helicarionidae) * o

3.Species which show a low tolerance of habitat disturbance (ie they are generally found in native bushland only) include –

Strangesta 'Ku-ring-gai' (Rhytididae) * O

Parmavitrina 'Central Coast' (Helicarionidae) * O

Meridolum middenense (Camaenidae) # O

Austrochloritis 'Sydney' (Camaenidae) # o

Elsothera sericatula (Charopidae) # .


Diet of native snails

Most of the species of snails found in Ku-ring-gai are herbivores. Meridolum species (Camaenidae) are known to show a preference for eating selected species of fungi which they locate by smell, though they will eat a variety of other dead and living vegetable matter and this may apply to other species. The Red Triangle slugs Triboniophorus feed on the biofilm on the trunks of trees and rock surfaces. Snails of the family Rhytididae are carnivores – feeding on other snails, though certain species are known to feed on worms.


Native snail habitats and preferred vegetation

Gardens and parks in Ku-ring-gai can be enhanced as habitats for native snails by plantings of the following selected plant species and noting particular habitat requirements listed which provide shelter, food and breeding conditions for snails.
Sclerophyll woodland and forest species

Tree species

  • Eucalyptus punctata the best all round eucalypt species because of the deep bark litter it produces around its base which provides shelter and food.
  • Eucalyptus saligna best eucalypt species for the Red Triangle Slug because of its smooth trunk which often shows the squiggly feeding trails of these slugs.
  • Eucalyptus tereticornis produces copious litter and fallen branches for habitat.
  • Brachychiton populneus not native to Ku-ring-gai but produces deep nutritious litter – a favoured habitat for snails in the central west, particularly the Charopidae.


Herbaceous plants, sedges and grasses

  •     Lomandra longifolia produces shelter beneath leaf clumps.
  •     Imperata cylindrica produces shelter beneath dense aggregations of leaves – often indicates alkaline soil conditions which are favoured by snails.
  •     Themeda australis good as general shelter.
  •     Xanthorrea spp. good for shelter in dry well drained sandstone areas.
  •     Gahnia spp. good for shelter in damp areas.

Vine thicket and rainforest species

Tree species

  • Ficus rubiginosa Native Ficus spp. produce nutritious litter and are favoured habitat for snails above any other species.
  • Ficus coronatus As above.
  • Livistona australis Fallen leaves are good habitat for Helicarionids (Peloparion)and Camaenids (Austrochloritis).
  • Hibiscus heterophyllus good for semi arboreal species (Peloparion)
  • Backhousia myrtifolia creates deep litter layer.
  • Acmena smithii creates deep litter layer.
  • Glochidion ferdinandi creates deep litter layer.
  • Ceratopetalum apetalum Endangered carnivorous snail Rhytididae SN 4 found in association with this species.
  • Callicoma serratifolia As above. Also good for Red Triangle Slug.

Vine/Scrambler species

  • Cissus antarctica & Cissus hypoglauca good for semi arboreal species & shade.
  • Rubus hillii good for dense cover.
  • Eupomatia laurina good for semi arboreal species.


Ground covers

  • Commelina cyanea good for shelter.
  • Adiantum aethiopicum good for shelter.
  • Doodia aspera good for shelter. 

Exotic plants that are particularly toxic to native snails

  • Cinnamonum camphora
  • Ligustrum lucidum
  • Ligustrum sinense
  • Ochna serrulata
  • Asparagus aethiopicus
  • Many other species of exotic plants

Shelter for snails in gardens

  • Hardwood logs – particularly if they are burnt.
  • Rock piles – particularly limestone or broken up concrete blocks (composed of Calcium Carbonate which is needed for shell construction), basalt.
  • Oyster shell piles (Aboriginal shell middens are important secondary habitats for snails because of the abundant Calcium within shells.)
  • Deep leaf and bark litter.

Garden construction to encourage snails

  • Rockeries.
  • Terraces and retaining walls using dry packed stone.
  • Using layers of stones, cobble and rock rubble under trees and shrubs out to edge of drip line of crown to retain soil moisture beneath.
  • Using stone circles around trees on lawns to trap leaf litter and retain soil moisture.

Addendum

To complicate things Peloparion iridis is now thought to be an introduction from SE QLD/NE NSW - it is native but not to the Sydney area - it was thought to be accidentally introduced last century - possibly through the Macleay estate at Elizabeth Bay (the Macleay family at one stage had a private botanical garden)。


References

Robinson. L. 1998. Field Guide to the native plants of Sydney. Kangaroo Press, 2nd Edition.

2004. A Guide to Berowra Valley Regional Park. The Friends of Berowra Valley Regional Park.

Smith, B.J. & Kershaw, R.C., 1979 Field Guide to the Non-Marine Molluscs of South Eastern Australia. Australian National University Press, Canberra.

Michael Shea

18. 7. 05