Tandonia sowerbyi is a species of air-breathing, keeled, land slug, a shell-less terrestrial gastropod mollusk in the family Milacidae.
This is a keeled slug attained in length.
This slug occurs in open habitats such as grasslands and shrublands; it can be abundant in arable land and gardens.
This slug is native to Europe, likely originally only to Greece. It is now widespread in southeastern and Atlantic Europe:
It is also present in:
This species has not yet become established in the USA, but it is considered to represent a potentially serious threat as a pest, an invasive species which could negatively affect agriculture, natural ecosystems, human health or commerce. Therefore it has been suggested that this species be given top national quarantine significance in the USA.