Lecidella elaeochroma

Here's a common lichen found on a Yew tree in Somerset. All three apothecia are from the same lichen. The section shows that the lichen is Lecideine and the KI+ reaction with lecanorine shape reaction narrows down to three groups of which only Lecidella is found on wood. Within the Lecidella group Lecidella looks to be the only species found on wood.

Lecidella elaeochroma ascus

Lecidella elaeochroma section

Lecidella elaeochroma spore

Lecidella elaeochroma