*Arion rufus* the Roundback slug is a species found Natively throughout Western and Souther Europe. Their present distribution in the United States spans from California, Maine, Michigan, New York, Oregon, Washington, and Wisconsin. They are large and bulky with long, course tubercles on the side and back. When contracted, the body resembles that of a bell. The species complex can only be differentiated by dissecting the genitalia. ©2021 Brandon Holt MSMI, CMI