Lecidea circinarioides Casares & Hafellner

in Casares-Porcel & al., Lichenologist, 28: 41, 1996.
Synonyms:
Distribution:
Description: Thallus crustose, chalky white, rimose-areolate, the areoles (0.3-)l-l.5 mm wide, convex, sometimes granulose, forming poorly delimited, thick, up to 5 cm wide patches. Pseudocortex formed by a thick hyaline layer of calcium oxalate crystals mixed with dead algal cells and hyphae; algal layer discontinuous; medulla white, thick, filled with calcium oxalate crystals. Apothecia numerous, appearing cryptolecanorine-aspicilioid, at first immersed in the thallus, later subsessile, frequently confluent and deformed by mutual compression, (0.5-)l-l.5 mm across, with a flat to slightly convex, black but finely white-pruinose disc and a thin, false thalline margin which is often shared by adjacent apothecia, formed by the areoles, from which it is finally separated by a crack. Proper exciple very thin, differentiated from the medulla by a deposit of a non-crystalline substance, of sinuous hyphae; epithecium olive-green 14-20 µm high, N+ purple, with a layer of c. 5 µm wide crystals visible under polarized light; hymenium colourless, 60-80 µm high; paraphyses coherent, branched and anastomosing, c. 2 µm thick at mid level, the apical cell slightly clavate; subhymenium and hypothecium colourless, c. 50 µm high, without crystals. Asci 8-spored, narrowly clavate, thick-walled, with a K/I+ pale blue tholus and a strongly amyloid, thin apical cushion, surrounded by a I+ blue outer layer, Lecidea-type. Ascospores 1-celled, hyaline, ellipsoid, (10-)11-12(-13) x (6-)7-8(-9) µm, c. 1.6 times as long as wide, frequently guttulate. Pycnidia inconspicuous, immersed, with greyish, irregularly shaped ostioles, the wall blue-green near the ostiole. Conidia bacilliform, hyaline, acrogenous, 8-10 x c. 2 µm. Photobiont chlorococcoid. Spot tests: cortex and medulla K-, C-, KC-, PD-. Chemistry: four unidentified substances.
Note: a peculiar species with aspicilioid apothecia, easily confused with species of Circinaria, but with 8-spored asci and smaller spores. It is fairly common in Spain, growing on gypsum in sunny-dry sites, and is also known from Morocco. To be looked for in the gypsum outcrops of Southern Italy, especially in Sicily.
Growth form: Crustose
Substrata: rocks
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual


Predictive model

Source: https://liquenesdealmeria.blogspot.com/2010/08/lecidea-circinarioides.html
Spain