Verrucaria calciseda

This lichen was found on a north facing vertical rock face. The apocethia are perithecia but I couldn't find any asci so initially thought they were pycnidium. Because of the lack of microscopic characters I resorted to visual identification narrowing down to a Verrucaria species. The three narrowed down to were: Verrucaria baldensis, calciseda and hockstetteri. The empty pits are pointer to eliminating hockstetteri leaving baldensis and calciseda. The two overlap in perithecia size and visually I preferred baldensis on frequency of the perithecia but the lack of cracks extending from the ostiole suggested that this is Verrucaria calciseda. Other lichen to look out for that look like this is Clauzadea immersa.

Verrucaria calciseda