Catillaria subviridis (Nyl.) Zahlbr.
Thallus more or less effuse, thin, rimose, beige, grey-green, grey-brown, matt. Apothecia numerous, 0.1-0.3 mm in diameter, disc flat to rarely slightly convex, blackish-brown if wet, black if dry, thin margin a little paler. Subcylindrical asci 45-55 x 10-16 µm with a thick blue I + top. Paraphyses with the apex bearing a blackish-brown "cap". Spores elliptical, 1-septate, 10-16 x 4.5-6 µm. Photobiont: chlorococcoid. No significant color chemical reactions. Maritime species a little nitrophilous coming on rocks rich in organic matter at the level of Verrucaria maura in the mesic supralittoral zone. Similar appearance and difficult to differentiate in the field from certain forms of Catillaria which can venture on the seashore such as: Catillaria chalybeia; Catillaria atomarioides and Catillaria lenticularis which have smaller spores.