I have collected some lyre-shaped apothecia on the stripped bark of Castanea sativa, on the wooden posts enclosing a meadow at an altitude of 450 m in Laviana (Asturias, northern Spain).
It has hyaline walled spores, with some longitudinal septa. Me = 31.7 × 11.4 µm; Qe = 2.8.
Could this be the genus Arthothelium?
Following the keys in Cannon et al. (2020), I have arrived at A. lirellans or A. orbilliferum, depending on whether I consider there to be one or more longitudinal septa.
I would like to hear the opinion of someone who has studied these genera previously. Many thanks.

Cannon, P., Ertz, D., Frisch, A., Aptroot, A., Chambers, S., Coppins, B., Sanderson, N., Simkin, J. & Wolselsey, P. (2020). Arthoniales: Arthoniaceae, including the genera Arthonia, Arthothelium, Briancoppinsia, Bryostigma, Coniocarpon, Diarthonis, Inoderma, Naevia, Pachnolepia, Reichlingia, Snippocia, Sporodophoron, Synarthonia and Tylophoron. Revisions of British and Irish Lichens 1: 3–48. DOI: 10.34885/173.