sentences: "Arion subfuscus" and "A. fuscus" can look similar to "A. distinctus" when preserved, but these species in life have bright orange mucus on the body and a pale sole, whereas in "A. distinctus" the sole appears yellow or orange from the sole mucus, but the body mucus is not coloured.However, reliable discrimination from other members of the subgenus "Kobeltia" is not always straightforward on external characters.