Candelariella vitellina (Hoffm.) Müller Arg. forma vitellina
Thallus crustose, areolate, composed of irregular subsquamulose granules, 0,5-2 mm, daisy heart like when numerous, yellow-mustard, yellow-orange, orange, brown-orange. Apothecia usually numerous, sessile, 0,5-1,5 mm diam., sometimes distorted, disc flat, dull yellow, darkerning when old, margin prominent, persistent, smooth to crenulate, concolourous or paler. Ascii 16-32-spored. Ascospores ellipsoid, simple or 1-septate (possibly both types coexist), 9-15 x 3-6,5 µm. Pycnidia frequent. Photobiont : chlorococcoid. Thallus and fruiting bodies: K- (this limits confusion with some similar Caloplaca species), or sometime K+ brownish from the yellow pigment calycin. Not especially maritime, common on nutrient-rich walls of harbour structures, pier rockfills, etc., less common on wood in polluted environments and notably on wood ship wrecks (see Candelariella vitellina forme lignicole). N.B. There is one morph, flavovirella (Nyl.) A. Henderson of which the thallus is bright yellow-green. Near the seashore this species must not be confused with Candelariella coralliza of which the thallus is very thick, markedly areolate, (without or) with a small number of apothecia. Numerous intermediate specimen may be found. Sometimes, Candelariella aurella is difficult to distinguish but usually is characterized by a small more or less brown-orange thallus on a black hypothallus.