1. Potamopyrgus antipodarum. Shell heights 4.5mm to 1.1mm. Umbilical chink on smallest, closed on others. Arrow indicates rounded adapical angle of aperture standing out from final whorl. Thickened aperture lips on top three mature specimens.
2. Potamopyrgus antipodarum. Shell heights 4.5mm to 1.1mm. Umbilical chink on smallest, closed on others. Arrow indicates rounded adapical angle of aperture standing out from final whorl. Thickened aperture lips on top three mature specimens.

Potamopyrgus antipodarum. Shell heights 4.5mm to 1.1mm. Umbilical chink on smallest, closed on others. Arrow indicates rounded adapical angle of aperture standing out from final whorl. Thickened aperture lips on top three mature specimens.