Lecanora hybocarpa on old beech trunk

Happy to hear from others who might disagree, but for what it’s worth, I wouldn’t hesitate to record your lichen as L. hybocarpa auct. br.

The only other British lichens with the same pattern of epithecial granules atop and descending between the paraphyses are L. pulicaris and L. sinuosa. The granules of both of those species are defined as fine (without discernible shape at 400x magnification), whereas the granules in your lichen seem to be coarser, in keeping with the specimens of L. hybocarpa auct. br. that I’ve observed.

You probably know that L. pulicaris and L. sinuosa also have somewhat different external morphologies as well. Your lichen doesn’t seem a candidate for either species from its appearance, especially not L. sinuosa with its very warty thallus dominated by semi-enclosed apothecia.

You could always see if your lichen is Pd- just to rule out L. pulicaris, though given the coarse granules and fawn-brown discs I personally wouldn’t think it necessary. And it wouldn’t be 100% foolproof anyway! No-one has demonstrated conclusively that the Pd- chemotype of L. pulicaris can be found in Britain as it is on the Continent, but there have been some strange observations: https://twitter.com/specanatura/status/1740325933310214160” class=”bbcode_url”>https://twitter.com/specanatura/status/1740325933310214160.