Cernuella virgata

Shell description

The shell is from 6 to 19 mm in height and 8 to 25 mm in width.

The coloration of the shell is quite variable, but there is often a creamy-white background, with a variable number of pale to darker brown markings. Some shells are banded at the periphery and on the underside.

Technical Description

For terms see gastropod shell

The 15 x 12–23 mm. shell has 4.5-5.5 convex whorls.The last whorl is initially angulated or rounded. The aperture is rounded with a whitish or reddish lip inside and margin is not reflected, The umbilicus is always open, 1/10-1/6 of shell diameterand sometimes slightly excentric. The cloour of the periostracum is whitish or yellowish, sometimes with red hue and usually with two brown colour bands on the upper side and 3-4 narrower bands on the lower side, initially finely ribbed, weakly striated at lower whorls.

Distribution

This snail is endemic to Mediterranean and Western Europe, including the British Isles. This species has been recovered from the Roman occupation of Volubilis, an archaeological site in present-day Morocco.

Cernuella virgata is an invasive species and an agricultural pest in parts of Australia, where it arrived around 1920. In Australia it is known as the "common white snail".

Another land snail which is present as an invasive in Australia, and which is sometimes confused with Cernuella virgata is the species Theba pisana. It is somewhat similar in appearance, and lives under similar circumstances. Theba pisana is however a larger species with a more inflated shell, lower spire and a nearly covered umbilicus.

Comparison of shells of Cernuella virgata and Theba pisana:

Behavior and human relevance

This species aestivates after climbing to the top of vegetation (or fences). This habit is problematic for farmers engaged in crop harvesting, because numerous snails are collected along with the crop.

Life cycle

The size of the egg is 1.5 mm.

Parasites

Cernuella virgata is as intermediate host for the terrestrial trematode parasite Brachylaima cribbi.

Gastronomy

Cernuella virgata, with Theba pisana, is consumed in Spain as a "tapa" in the bars, especially in Andalusia, where snails are known as "Chichos" snails.