Llimonaea sorediata Van den Boom, Brand & Elix
Thallus crustose, 2-5 cm diam., less than 0.5 mm thick, minutely granular, slightly rimose and radiating from the center, center more or less areolate, typically pale pink, cream-pink, very pale pink-ochraceous when moist, grey-whitish when dry, covered with minute whitish to pinkish soralia sometimes forming granular piles, notably towards the center, edged by a black prothallus, conspicuous in case of mosaics. Very seldom fertile, apothecia unknown in Europe, round or elliptical, brown-blackish to black. Ascospores fili-fusiform, 8-14-septate, 35-50 x 4.5-6 µm with a 2 µm perispore. Photobiont: Trentepohlia. C+ instantly and persistent red, K-, KC+ red, Pd-. Often found in the aerohaline zone (rarely inland when exposed to winds from the sea), in large conspecific colonies more or less confluent and mosaic-forming on vertical walls of acid rocks near the seashore, always avoiding direct sun and rain and preferentially under overhangs and in holes, see: Llimonaea sorediata foreshore rocks form. Also often found on North walls of chapels, see: Llimonaea sorediata chapel wall form, and seldom on concrete or stone walls, see: Llimonaea sorediata concrete walls form. In addition very rare forms may be found on glass, see: Llimonaea sorediata glass form and wood see: Llimonaea sorediata wood form,, very rarely on bark: see Llimonaea sorediata forme corticole. Fairly common species, but little know, belongs to the Sclerophytetum circumscriptae, and forms mosaics with other species. N.B. On walls, notably chapel walls, this species may be mistaken with Dirina massiliensis f. sorediata forms, that grow on acid rocks and share the C+ red reaction, (rather slow reaction compared to Llimonea sorediata), with a thicker thallus (>1 mm), not pink but lilac to purple tinged, prothallus grey-ochraceous to brown-black instead of intense black, grey to grey-ochraceous soredia instead of pink (although soralia may be pinkish at first). N.B. Identification sometimes may require chemical analyses, especially in fequent cases of specimen varying from the type.