Yes, it is known from the Channel Islands in southern California, as well “scattered localities in central and southern Europe”. It is narrow-lobed (< 0.5 mm wide), very closely attached to rock or bark, with “pustules dissolved into granulate soredia”, both cortex and medulla should have atranorin (K+ yellow).
I’d say this matches your specimen well. Another great observation! Probably the finest photos of this species on the web. :)