I'm going to put this out as a reader challenge while I do some research myself. I came across this somewhat disturbing spectacle in a local bit of bushland. The spider (which was on a vertical trunk as it happens) appears to be a huntsman which has been/is being consumed by some sort of parasitic fungus. It certainly makes me shudder. Apologies for the photo quality, I only had my happy snap camera with me at the time.