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 in well-lit areas, more dirty yellow or slightly greenish in shaded areas. 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 utriform, 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 and there are forms with the margin of the apothecia K+ reddish. 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), also on textiles used to fix pebbles or sand at the seaside: Candelariella vitellina forme sur textile de protection des sols, more rarely on metal and in particular iron: Candelariella vitellina forme sur fer.

N.B. 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.

N.B. There is one morph, flavovirella (Nyl.) A. Henderson of which the thallus is bright yellow-green.

N.B. Sometimes, Candelariella aurella is difficult to distinguish but usually is characterized by a small more or less brown-orange thallus on a black hypothallus and asci with 8 spores.