Catillariaceae Catillaria chalybeia Growth type crustose. Chemical reactions negative Common on nutrient-enriched siliceous rocks, pebbles and walls. Occasionally found on timber and tree trunks. Very variable. Thallus thin or cracked-areolate, grey, greenish or grey-black. Black prothallus often present. Apothecia flat or +/- convex, discs black with thin margins. Spores are 1-septate, 8-12 x 3-5 µm. Hymenium usually bluish-green at base, paraphyses with dark, swollen tips. Photobiont Myrmecia. Micro photo below. Can be confused with other Catillaria ssp., Micarea erratica and saxicolous Amandinea punctata

Microscope photograph

Catillaria chalybeia
On pebble. Studland Heath, Dorset. April 2013