Opegraphaceae Opegrapha rupestris # Lichenicolous on Bagliettoa baldensis (Verrucaria baldensis) and Bagliettoa calciseda on natural limestone rocks and memorials Found singly or as scattered clusters of small lirellae with a narrow central slit. Asci are 8-spored, the spores 3-septate, 14-22 × 5-8 µm, hyaline becoming brown when over-mature. Exciple K+ brown-red in section. Microscope photograph below. Similar: Opegrapha hochstetteri occurs on Verrucaria hochstetteri and V. muralis and Opegrapha opaca on Verrucaria nigrescens and V. viridula. Other lichenicolous Opegrapha species include Opegrapha parasitica on Aspicilia calcarea and Opegrapha pertusariicola on Pertusaria leioplaca

Microscope photograph

Opegrapha rupestris
Arne, Kimmeridge and Branksome Park, Dorset. February and March 2014, February 2017