Eastern Speckled Shield Lichen

Eastern Speckled Shield Lichen - Punctelia bolliana

I arrived at this identification based on the following features:

• bluish-grey thallus
• growing on the bark of deciduous trees 
• rather large brown apothecia (first picture below)
• brown to black dots (pycnidia) on the thallus surface (see second picture below)
• white, grainy spots (pseudocyphellae) on the thallus surface (see third picture below)
• whitish to tan underside with pale rhizines
• K + on the cortext (I got a greenish-yellow color)