This time I decided to use A Preliminary World-wide Key to the Lichen Genus Pertusaria, which pretends to be a world-wide key for this genus and includes more than 700 species. This key as several sub-keys according to: the presence/absence of apothecia, the macro feature disciform/verruciforme of apothecia, the habitat rock/bark, and the number of spores per ascus. The obvious choice (after microscopy) of the sub-key Group 20. Apothecia present, disciform; ascospores 8 per ascus, on wood gives immediately Pertusaria hymenea, since is the only one in this group with the dimension of spores compactible with the values observed: (72.7) 74.2 - 82.8 (87.6) x (29.7) 32.3 - 35.3 (35.6) µm Q = 2.2 - 2.5 (2.7) ; N = 10 Me = 78.5 x 33.4 µm ; Qe = 2.4.