Results and conclusions are presented on morphological and field observations made on a collection of land slugs from the Arboretum and Botanical Garden administered by the Universidad Austral de Chile at Valdivia, as well as various records from other collection sites in southern Chile. Based on some anatomical features, the individuals studied were identified as Arion intermedius Normand, 1852, endemic to eastern Europe, and known from various locations around the world for its invasive capacity, apparently facilitated by its feeding habits and particularly by its reproductive strategy of strict self fertilization which is unusual in pulmonates. This is the first report of this species, introduced to Chile by human activities, added to previous literature citing the presence of Limacidae, Agriolimacidae, and Helicidae. This slug is a potential threat to agriculture and to native flora and fauna of Chile