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Meridolum corneovirens (Pfeiffer, 1851)
(Family Camaenidae)
Meridolum corneovirens is a native landsnail similar in size to the common introduced Garden Snail Helix aspersa.
In 1997 it was declared an Endangered Species under the New South Wales Threatened Species Conservation Act because its
habitat has been largely destroyed.
This snail lives in a very restricted area of western Sydney between Prospect and Liverpool to the east and the Hawkesbury-Nepean
River to the west. Its reaches north to the Windsor-Richmond area and south to Picton. This region known as the Cumberland
Plain is recognised as a special habitat with its own distinct soil and vegetation type. This region is being covered in
houses and other buildings as Sydney expands westward and the home of Meridolum corneovirens is being destroyed.
The only way to protect this snail from extinction is to identify and protect parts of the remaining Cumberland Plain Woodland
which still have populations of the snail.
What does the snail look like?
Comparison between Meridolum corneovirens (left) and the common introduced Garden Snail, Helix aspersa (right).
The shell of Meridolum corneovirens is relatively thin, semitransparent, and uniform in colour while that of adult
Helix is strong, opaque and with a mottled colour pattern.
Photos: Bill Rudman.
The shell grows to about 25-30 mm in diameter and ranges in colour from a uniform horny-yellow to dark brown. The colour
of the shell is quite uniform although the edge of the shell around the 'mouth' or 'aperture' is often white or lighter
in colour than the rest of the shell. The underside of the shell is often glossy in appearance. The only similarly sized
shell it is likely to be confused with in western Sydney is the common introduced Garden Snail (Helix aspersa). There
are a number of obvious differences. The shell of the Garden Snail almost always has a pattern of dark patches on a lighter
background while the shell of Meridolum is uniform in colour with no patching. Some patterning may be seen on the
shell near the aperture but that is colour on the animal inside the semi-transparent shell. The shell of the Garden Snail
is more inflated and has a higher spire than Meridolum, and the shell is much more strongly calcified (much thicker)
than that of Meridolum. If you were to squeeze the shell of the Meridolum in your fingers it would easily
crack whereas it is more difficult to break the shell of a large Garden Snail the same way.
Where do they live?
The normal habitat of Meridolum corneovirens is in open eucalypt woodland under fallen logs and debris and in bark
and leaf litter around the trunk of gum trees, or they can be found burrowing in loose soil around clumps of grass. Today
with much of its original habitat disturbed, the snails are also found living under piles of old building rubble, under
bricks, in piles of old timber, under car bodies and sheets of corrugated iron. In times of drought they are also able to
burrow a few centimetres into the soil. Surveying areas for Meridolum corneovirens during dry periods is not very
useful for they may be buried in the soil. If only dead shells are found this does not mean that the population is destroyed.
Again they could all be buried in the soil or hiding in inaccessible places.
 
Click on images for details
What do we know about its natural history?
Meridolum corneovirens, like many Australian landsnails, feeds on fungi. Fungi play an important role in the ecosystem
helping to recycle the nutrients in rotting and decaying plant and animal material. Fungal feeders play an important role
helping to spread fungal spores throughout the environment. Unlike the introduced Garden Snail which is a garden pest eating
new seedlings and new plant growth, Meridolum corneovirens will not eat, let alone destroy garden plants.
Apart from this we know almost nothing of its biology and have little idea how well it is surviving. The records marked
on the distribution map are of specimens that have been collected by chance over the last 140 years. No organised survey
of this species has been undertaken.
Past distribution
Meridolum corneovirens was common in the open dry sclerophyll woodlands of the Cumberland Plain from the foot of
the Blue Mountains east to Liverpool and Prospect, and from Windsor in the north to Picton in the south.
Present distribution
No comprehensive survey of its present day distribution has been undertaken but it is known to survive in remnant patches
of the typical Cumberland Plain bushland. Even within this range several 'morphotypes' exist suggesting that there may be
considerable genetic differences between surviving populations.
Are there other species of Meridolum?
Our knowledge of Australian landsnails still has many gaps. There appear to be a number of species of Meridolum in
south-eastern Australia from Victoria to southern Queensland east of the Great Dividing Range, with the most being found
in New South Wales. Each species seems to have its own distinct geographic distribution with little overlap between 'species'.
An extensive study of the anatomy and distribution of these snails is needed. In the Sydney region, outside the Cumberland
Plain, there are possibly many more species most of which are at present unnamed. Although some populations are protected
in National Parks, the habitats of many populations, like Meridolum corneovirens, are unprotected.
About the Cumberland Plain Woodland
The Cumberland Plain Woodland is a unique ecosystem within the Sydney Basin, stretching from Richmond and Windsor in the
north to Picton in the south. It is bordered in the west by the foot of the Blue Mountains and stretches east to about Liverpool
and Parramatta. This flat or gently rolling plain of shale, limey clays and alluvial gravels with a cover of dry eucalypt
forest is in stark contrast to the surrounding sandstone plateau with quite different plant communities and acidic soils.
It is drier and with greater temperature extremes than the rest of Sydney. Unfortunately this ecosystem is ideal for human
habitation and Sydney's inexorable growth westward towards the Blue Mountains could destroy much of the little that is left.
The declaration in 1997 of the Cumberland Plain Woodland as an Endangered Ecological Community is useful, but it is vital
that the smaller animals that are found only in this habitat type are identified and protected so that protective measures
are appropriate not only for the plants but for the animals as well.
Further information
Threatened and Endangered Landsnail species
Meridolum corneovirens | Placostylus bivaricosus | Thersites mitchellae
Dr Rudman | Molluscs Homepage
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