Caloplaca teicholyta (Ach.) J. Steiner
Thallus crustose, rounded, 5-10 cm diam., rather thick, slightly placodioid, lobate margin, lobe tips often poorly differentiated, flat or slightly convex; center granulose to verrucose with granular whitish to grey-blue soredia, overall colour dull white to white-greyish with darker, dark grey, grey-blackish center, possibly eroded. Almost always infertile in our prospection area, otherwise crowded at the thallus center, 0.5-0.75 mm diam., innate at first becoming sessile, disc concave at first, becoming flat, reddish, brown-orange, dark orange, or rusty, sometimes pruinose and whitish; proper margin red, paler than the disk, exciple flexuose, swollen, withish and concolourous to the thallus. Ascii clavate, 50-80 x 20-25 µm. Ascospores polarilocular, ellipsoid, 15-18 x 7-10 µm. according to literature, 12-18 x 6-9 µm according to our measures, septum often under 4 µm wide, up to 1/4 of the length of the ascospore. Photobiont: Trebouxioid. Cortex K-, apothecia K + purple. Rare in our prospection area, on alkaline well-lit substrata and notably on limestone, occasionnally on cement or concrete walls notably of chapels. N.B. Fertile thalli with apothecia may be compared to those of Caloplaca albolutescens which has no soredia, less reddish apothecia and unlobate thallus margin. The latter is also less thermophile and growths northwards.