Lichen with tiered perithecia

Lichen with tiered perithecia

Observation - Lichen with tiered perithecia - UK and Ireland. Description: Lichen with black, tiered perithecia (upper part of first picture) growing on siliceous sandstone part of chapel wall facing south. Small perithecia (compared to black lecideine apothecia near bottom of first picture). No clear thallus. Sessile peritheci

Lichen with black, tiered perithecia (upper part of first picture) growing on siliceous sandstone part of chapel wall facing south. Small perithecia (compared to black lecideine apothecia near bottom of first picture). No clear thallus. Sessile perithecia, not immersed, each with raised circular tier around the ostiole (second picture). Some perithecia look broken (third picture). Possibly Thelidium minutulum. (Appreciate details of spores probably needed for an identification but wonder if this perithecia shape is found in range of lichens.)