About Arion intermedius Normand, 1852
Adult Arion intermedius, commonly known as the hedgehog slug, measure 1.5 to 2 cm in length. Their color and patterning are highly variable: individuals may be white, pale yellowish, or gray, and may or may not have lateral bands. They have darker gray tentacles and a yellow or orange foot sole. When contracted, their body becomes compact and nearly bell-shaped. The tubercles that texture the dorsal surface of their body taper into sharp, prickle-like points, which is the feature that inspired the common name hedgehog slug. This tubercle shape is diagnostic for the species, though the prickly texture usually disappears after the slug is preserved. Another identifying characteristic is a line of very small black dots along the anterior margin of the sole, though these dots are not always visible. The species is native to Western Europe and part of Central Europe, ranging from northern Portugal to western Poland, and from southern Scandinavia to northern Italy. It is considered native to Czechia, where most of its local records come from various forest types. Records from Slovakia, Austria, Hungary, Bulgaria, Finland, Iceland, and southern Italy, which lie at the edge of the species’ European range, are more likely the result of introductions. Arion intermedius has also been introduced to many regions outside of Europe, including North America, South America, Australia, New Zealand, South Africa, and some Pacific islands.
