06 Arion (Mesarion) subfuscus (Dusky Slug)
A medium-sized species, Dusky Slug might be confused with Tawny Soil Slug (Arion owenii) at first glance; they are both brown (although quite variable in shade) and usually have dark pigmentation down the back. However, Dusky Slug is larger than Tawny Soil Slug, and has much finer tubercles, a pale sole not stained by mucus (the sole of Tawny Soil Slug is stained yellow-orange), and bright orange body mucus, sometimes to the point of making the slug look glazed with an orange syrup. This may not be obvious when the mucus is on the slug, so you need to dab the slug with a tissue, or rub it gently with your thumb. Don’t forget to photograph the tissue or your thumb (as well as the slug) if you are submitting your record for verification, as the mucus colour is an important diagnostic feature. The foot fringe does not contrast with the body sides and has narrow stripes (Tawny Soil Slug does not have a striped foot fringe). Dusky Slug appears to be unfussy in its habitat requirements at St Nicks, but like many slugs is usually found under logs and stones.
06 Arion (Mesarion) subfuscus (Dusky Slug)
A medium-sized species, Dusky Slug might be confused with Tawny Soil Slug (Arion owenii) at first glance; they are both brown (although quite variable in shade) and usually have dark pigmentation down the back. However, Dusky Slug is larger than Tawny Soil Slug, and has much finer tubercles, a pale sole not stained by mucus (the sole of Tawny Soil Slug is stained yellow-orange), and bright orange body mucus, sometimes to the point of making the slug look glazed with an orange syrup. This may not be obvious when the mucus is on the slug, so you need to dab the slug with a tissue, or rub it gently with your thumb. Don’t forget to photograph the tissue or your thumb (as well as the slug) if you are submitting your record for verification, as the mucus colour is an important diagnostic feature. The foot fringe does not contrast with the body sides and has narrow stripes (Tawny Soil Slug does not have a striped foot fringe). Dusky Slug appears to be unfussy in its habitat requirements at St Nicks, but like many slugs is usually found under logs and stones.