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Lecanora praepostera auct. non Nyl.

Synonyms:

Lecanora schistina (Nyl.) Arnold

Lecanora gangaleoides f. schistina Nyl.



Family: LECANORACEAE

Habitat: Xeric supralittoral  zone

Description

    Thallus crustose, areolate, (lobes and warts absent), areoles flat to slightly convex, 3-10 cm across, dull cream, cream-greyish, pale cream-greenish, prothallus most often present, dark-blue to blackish with light and dark zones. Apothecia usually numerous, often clustered towards the margin or the center, immersed at first then markedly sessile, 1-1.5 mm diam., disc flat, often absent and then leaving small empty cupules, pale brown, grey-brownish, sometimes pruinose, dark brown to blackish when old, sometimes with patches of different colours, exciple determinate, persistent, becoming wavy to crenulate, whitish, pale brownish. Ascospores simple, ellipsoid, 11-15 x 6-8 µm. Photobiont: Trebouxia. C-, K+  yellow > red, Pd+ golden yellow to red-orange. On acid sheltered more or less vertical walls of rocks along rocky coasts and cliffs. Rather frequent on schists and micaschists, notably near the seashore. This species has been named Lecanora schistina by French authors. May be confused with Lecanora bandolensis that grows on less acid and well-lit rocks and with a thicker thallus, more whitish, with negative chemical spot tests and above all with apothecia discs spotted with dark green. May also be confused with Tephromela atra often growing nearby but with apothecia discs never brownish but black even when young and with a much more whitish thallus, K+ yellow. Not to be confused with two other  close species having the same chemical reactions: Lecanora gangaleoides of which the thallus is markedly verrucose and exciple determinate, rather thick and whitish and Lecanora cenisia ss. auct. brit. of which the thallus is grey-bluish and apothecia most often with brown-red discs.*







Lecanora praepostera Pointe d'Armorique
Alain GERAULT



Lecanora praepostera Pointe du Raz
Alain GERAULT



Lecanora praepostera Roscanvel La Fraternité
Alain GERAULT



Lecanora praepostera Cap de la Chèvre
Alain GERAULT



Lecanora praepostera Réactions (en haut à droite Lecanora gangaleoides) Cap de la Chèvre
Alain GERAULT



Lecanora praepostera Pointe de Pen Hir 1
Michel DAVID



Lecanora praepostera Pointe de Pen Hir 2
Michel DAVID



Lecanora praepostera Pointe de Pen Hir 3
Michel DAVID



Lecanora praepostera Pointe de Pen-Hir 4
Michel DAVID



Lecanora praepostera Pointe de Pen-Hir 5
Michel DAVID



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