I don't think it's the nostil mat.  I've tried making it completely black with no specular and I still get that.  I had IDL on (3 bounces) so I'll look into my IBL settings.  I did have one infinite light (for the sun) though.  Also shadows were ray traced and I tried setting them very low.  For this one it is .0001 on the shadow min bias.

It looks like what is happening is the front of the nose isn't blocking light from hitting the back. 

WARK!

Thus Spoketh Winterclaw: a blog about a Winterclaw who speaks from time to time.

 

(using Poser Pro 2014 SR3, on 64 bit Win 7, poser units are inches.)