I picked up a twig on a path in the Wye Valley woodlands (relatively unpolluted for Gloucestershire) with a clean and tidy looking Lecanora which I thought would be argentata, which is not uncommon in the county, or just maybe horiza. However,checking under the microscope it was immediately obvious that there was a good layer of crystals on the epithecium which appeared not to be descending into the hymenium, as well as a few big crystals in the margin. Lecanora chlarotera s. str. would be great – a county first as far as I am concerned because everything I have checked equates to hybocarpa. The crystals dissolve in K, but unfortunately they don’t seem to dissolve in Nitric Acid (I’ve been quite patient!)
K+ yellow, Pd- (or very very weakly yellow), C-, UV maybe dull orange.
I’d appreciate some guidance, please.
