Verrucariaceae Placopyrenium canellum # (Verrucaria canella) Lichenicolous then crustose. Photographs on Aspicilia calcarea It is initially parasitic on thalli of Aspicilia calcarea on unshaded natural limestone outcrops, but later develops an independent thallus. The pale grey thallus with a slightly darker margin is divided by thin lines which become deep cracks as areoles mature and become discrete. 1-5 perithecia develop on each areole, usually immersed but occasionally marginal. Asci 8-spored, spores simple, (19-)21-27(-30) x (7-)7.5-10 µm Similar: Placopyrenium fuscellum is initially parasitic on thalli of Verrucaria nigrescens

Placopyrenium canellum
Portland, Dorset. February 2016