is that you’re doing such good and meticulous work that Dr. Schumm might be happy to take the time to help you with advice, identifications and/or supply literature or unpublished resources which you may not have. Since it is such a small, relatively poorly-known field, lichenologists are often excited to learn about serious amateurs and will go out of their way to encourage and help where they can. It is certainly worth taking the time to write and introduce yourself. The worst that can happen is he ignores you. Maybe you could use one of your uncertain observations as an excuse to write. If he sees the care you take in observing spot tests and microscopy and researching, he may be impressed and wind up being very helpful.

… the work cited in the summary of your message, from the time it was available in pdf form in the page of Dr. Felix Schumm. But, I don’t understand your suggestion.

zaca, at some point you might communicate with Dr. Felix Schumm, author of “Flechten Madeiras, der Kanaren und Azoren.” His email address is on his home page. I think he would appreciate hearing from you, and I know that you could write to him in English.

After collect a piece of the specimen, I found another specimen – considered in MO67160 – and made the microscopic analysis of both specimens together. The results obtained clearly show that, in fact, they belong to one and the same species.
The microscopic analysis revelled – see the attached photos – a photobiont constituted by a green alga, with some big cells (up to 15 µm in diameter), spores transversally 3-septate (average measures for the specimen in this observation: 18.1 × 4.2 µm (N=23)), and straight paraphyses ended with a globose cell. According to the conclusions drawn in MO67160, I believe that this specimen is a Toninia aromatica. I already uploaded a photo with a set of pictures taken from the microscopy.

… are notoriously difficult. Lecidea is a good hypothesis to start with, but microscopy will certainly be required to say anything with confidence.