Sarcogyne pruinosa (Schaer.) A.Massal.

Surprisingly the pebble was covered in this lichen on all faces. Maybe regular movement in loose ground facilitadted lichen development on all sides.

There is a hint of an epilithic thallus, more a white dusting, green when scratched than an actual formed thallus.

Flat balck apothecia disks. Blue grey pruinose with pruina less prominent on the margin.

Apothecia are seated in shallow depressions in the soft limestone.

Apothecial section in water with pigmented epihymenium and unpigmented hymenium and subhymenium. Hymenium approximately 82 µm thick.

Hymenium with euamyloid IKI (blue to Lugol's solution) reaction.

K-I blue hymenium

(Lugol after treatment with ~10 KOH)

Spores (4,5)5,1-5,9(6,2) x  1,9-2,2 µm