Habitats of Molluscs: Calcareous Grassland and Established Sand Dunes

Dry, calcareous grassland is mostly "man-made" in Britain (dunes are an exception), but much of it has been around for thousands of years. It has a rather characteristic fauna, which includes a number of introduced species that have naturalised very well. As with woods, the presence of rocks makes a difference, and where there are screes, cliffs or limestone pavements, many "woodland" or "generalist" species may occur too.

If grazing pressure is reduced, as happened on chalk downs in the south and east in the middle of the last century, the grass gets much longer, and most of the characteristic species disappear. Some can be found on drier roadside verges in calcareous districts, and many are found on calcareous sand dunes.

Chalk grassland
Calcareous grassland

Calcareous sand dunes

The nomenclature used in the list follows "An annoted list of the non-marine mollusca of Britain and Ireland." by Dr. Roy Anderson, 2005 in Journal of Conchology Vol. 38: Part 6 pages 607– 637, which may also be accessed from the menu to the left under 'British Non-marine List'

Candidula gigaxii	Scarce; southern; an introduced species.
Candidula intersecta	Common; widespread; an introduced species.
Cernuella virgata	Common; an introduced species.
Helicella itala	Occasional; native; a species which seems to have suffered badly from the abandonment of traditional farming.
Monacha cartusiana	A very rare introduced species; restricted to SE.
Pomatias elegans	Occasional; this species requires loose, moderately deep calcareous soil. It can be found in a variety of habitats, including woodland, if the soil is not compacted.
Pupilla muscorum.	Frequent; a very typical species of short calcareous grassland. Like Helicella itala, it has become rarer as grass has got longer.
Trochoidea elegans	A very rare introduced species; restricted to SE.
Truncatellina callicratis	Very rare.
Truncatellina cylindrica	Very rare.
Vallonia costata	Common; this is a more tolerant species than V. excentrica (below), and can be found also in dry, open woodland.
Vallonia cf. excentrica / pulchella	Common; the first of these is the form found in dry grassland; the latter tends to occur in wetter open places. There is some doubt as to whether these are two species, or just ecological variants.
Vertigo pygmaea	Frequent.