Arion hortensis form B Arion owenii is a species of small air-breathing land slug, a terrestrial pulmonate gastropod mollusc in the family Arionidae, the roundback slugs.

In slugs it is often difficult to establish good criteria for identifying species using external features or internal features, as colouration can be quite variable, and the rather plastic anatomy makes diagnostic anatomical features difficult to establish.

An up to 35 mm long roundback slug.

The colour is usually brown with dark colour bands, which can be interrupted (dark dots instead of bands), the sides are greyish.

The surface with characteristic very regular and rather sharply ridged tubercles.