Vahliella atlantica  

Thallus squamulose, dark grey, spreading irregularly, forming a crust on the substrate, partly isidiate, occasionally becoming subfruticose, to 5 cm diam., 100-150 (-200) μm thick. Upper cortex distinct, of 2-3 layers of short, thick-walled cells. Medulla loose, containing clusters of Nostoc, individual cells 4-5 μm diam., gradually merging into rhizohyphae below. Lower cortex lacking. Hypothallus blue-black, thin, variable. Soredia absent.
Anamorph: not known.
Teleomorph: ascomata apothecia, to 2 mm diam., laminal, often proliferating and occurring in clusters. Disc brown, eventually becoming convex, with a variable granular blue-grey thalline margin that often obscures the narrow (to 40 μm broad) cellular proper exciple. Hymenium 100-120 μm high, faintly brownish, composed of compacted, intricately interwoven hyphae, reacting I+ blue-green rapidly changing to red-brown (hemiamyloid). Subhymenial layers to 150 μm high, sometimes brownish, of intricately interwoven hyphae. Interascal tissue of unbranched septate paraphyses ca 2 μm diam. with clavate, pigmented apices. Asci to 100 × 15 μm, clavate to  ± cylindrical, with a ± flat amyloid layer below the apex and a hardly thickened cap, 8-spored. Ascospores 15-25 (-30) × 6-8 μm, ellipsoidal, hyaline, aseptate, smooth-walled, without a perispore, gelatinous sheath or appendages, often with internal oil droplets which tend to adhere forming plasma-bridges which may appear as incipient septa, but which dissolve in K.
Chemistry: no lichen substances detected by TLC.