03 May 2006

A confusing snail in the backyard

These land snails are among the mollusk denizens of the yards around my house. They usually hide under the rocks, but one summer we had more than a hundred of them aestivating on our garage door.

The taxonomy of the species in the genus Cochlicopa has long been a source of confusion and controversy. The exact number of Cochlicopa species in Europe depends on whose opinion one accepts. Giusti & Manganelli1 reported the results of their study of about 500 specimens of Cochlicopa from one location in Italy that showed that "Without signs of discontinuity, the specimens pass from individuals of the type C. nitens, through intermediate forms and C. lubrica and C. repentina-like forms to C. lubricella types. While the shell form changes, the genital tract details remain remarkably constant." One source of this phenotypic variability may be that these snails seem to be able to reproduce without mating thru selfing or parthenogenesis, thus creating different strains. Georg Armbruster has also been studying the European species and a short summary of his views are here.

I am tentatively identifying my snails as Cochlicopa lubrica. They are small snails with shells about 5 mm long. I will probably post about them again in the future.

1. Giusti, F. & G. Manganelli. 1992. The problem of the species in malacology after clear evidence of the limits of morphological systematics. Proceedings of the 9th International Malacological Congress, Gittenberger & Goud (eds.). pp. 153-172.


pascal said...

What are the white flecks just inside the apertural lip? Shell coloration, or little white things on the snail?


White specks inside aperture look like the patterns on the edge of the mantle.

Whitish areas on the shell towards the apex are areas where periostracum was worn. Probably they eat each other's shells for calcium.