Pectenia atlantica (Degel.) P. M. Jørg., L. Lindblom, Wedin & S. Eckman morpho cyanoloma

    = Degelia cyanoloma  (Schaer.) H. H. Blom & Lindblom

   Thallus in irregular rosette, often quite large, 10-15 cm at its greatest length, formed of lobes with slightly rounded and raised apices, these lobes are segmented into concave segments with a rounded end marked by concentric streaks or wrinkles ( like growth streaks or oyster shell pattern) but also radially and longitudinally by very fine streaks only visible under a magnifying glass, isidia absent or uncompletely developed toward the center, upper surface lead grey-blue when wet and pale grey-brown, blueish when dry, lower surface covered with a coarse blue-black tomentum, prothallus thin, fringed, blue-black (the tomentum of the lower surface and the fringe is much less important than for Pectenia plumbea morpho plumbea). Apothecia in low number, scattered all over the thallus, dark brown-red at first, soon brown-black to black, pale thin exciple, usually persistant. Ascospores and chemical spot tests as Pectenia plumbea morpho plumbea except that, according to our measurements, the size of ascospores is 15-20 x 6-9 µm.  Photobiont : Nostoc. Chemical spot tests negative. Hyperoceanic species growing on mossy trees of mild, humid woodlands near the sea.

N.B. Very close to and confused for long with Pectenia plumbea morpho plumbea and considered by some authors as a hyperoceanic variant. Degelia atlantica morpho cyanoloma differs notably by its large size, its lobes displaying more pronounced ribbed and less abundant apothecia soon brown or even blackish, suggesting  Pectenia atlantica s. str  not isidiate as admitted by some authors and confirmed by certain molecular biology analyses.