Potamopyrgus antipodarum


Description (shell):
Shell of six tumid whorls, often encrusted with black deposits so that little of the appearance of the spire is discernible. Last whorl large; aperture ear-shaped or oval, with a thickened peristome in mature shells; inner lip occludes umbilicus. In some shells, notably from brackish water populations, a spiral keel may be present, with or without periostracal bristles; some have a spiral row of bristles but lack keel.

Up to 6 x 3 mm.

Beneath black encrustations the shell is pale horn-colour.

Body with a long, narrow, bifid snout, evenly and darkly pigmented, with pale transverse band anteriorly. Cephalic tentacles long and setose, pale with darker base; white spot behind each eye. Mantle edge without pallial tentacle.

Common in a variety of freshwater and brackish (<16 รค) habitats, often with Ventrosia ventrosa in the latter. It is a New Zealand species, introduced to Europe by way of Australia.

Widely distributed throughout Europe.