Lichens on the Lackawaxen

Over the recent holiday break, I was up in the Pocono Mountains region of Pennsylvania. I was going to spend part of the day looking for river scour sites along the upper Delaware River however, ice-covered roads due to freezing rain prevented that from happening. Instead I ended up at the D & H Canal Park at Lock 31 along the Lackawaxen River, outside of Hawley, which is a local historic site. I went for a brief hike, including some quick peeks at some accessible sites along the river. At one of these sites, I came across this interesting lichen on a small rock along the water's edge. I collected a small sample of it and texted photos to one of my colleagues. We determined that it is likely a species of Dermatocarpon, a genus of lichens in the family Verrucariaceae, also known as the "stippleback lichens". There are two known species in Pennsylvania and both of them are tracked by the Heritage Program. We don't have a full species on it yet, but it compares favorably to D. muhlenbergii.