Confidence: I'm as sure as I can be.
Notes: The poster does not give a Latin name to indicate what he/she means by "black tar lichen", though I am guessing that Verrucaria maura is meant. If so, then yes, it is a Verrucaria, but not V. maura. To be honest, I wasn't going to bother with this, far too underexposed, but in a moment of boredom I have copied it into PhotoShop and brightened up the image. Most likely it is V. nigrescens, but I cannot rule out V. fusconigrescens or a dark variant of V. viridula.