Infected Slugs: Case #7

Similar to Case #6, this slug (Lehmannia valentiana) also has a misshapen mantle, which ends abruptly, leaving the neck exposed. Thus you can see dark- and light-colored forms beneath the skin which normally should be protected. Whether these forms are parasitic growths or organs is uncertain. The slug has no external growths on its body, but the abnormalities of the mantle alone are sufficient for concern. At the very least it's a mutation that could cause trouble for the slug. In addition, the tail is blunted, which may or may not be significant.

Ok, so the neck is white in this photo...

Then there's a small dark mass...

Now a very large one...an organ mass, perhaps, that's normally concealed by the mantle?

Here are some photos which provide a good comparison of a healthy slug and a possibly sick one:

You can see that dark mass again on the left side...

At least you can see the eye-stalks clearly in these photos because of the translucence of the slug's skin. A dark thread runs from the eyeball down tentacle, through the neck (I believe towards the nerve ring). 

In conclusion, this slug could simply be suffering from a mutation of its mantle, with no influence from parasites at all.