I've now seen two of these slugs this year - and they are big ones. I found them both in the vicinity of a seldom used gully-trap.
I hope I'm right by slotting it into the Lehmannia sp catagory (Family: Limacidae)
I believe Lehmannia is an introduced model from Europe.
(Click image to enlarge)
Finding any gastropod is a bit of a novelty - so be patient with me, please! :)
I couldn't access CSIRO databases yesterday - but I might wander over now and check a little further.
2 weeks ago