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Arthonia atra (Pers.) A. Schreid.                                  = Opegrapha atra Pers.

Synonyms:

Opegrapha atra  Pers.

 

 



Family: ROCCELLACEAE

Habitat: Ubiquitous

Description

    Thallus crustose, thin, smooth, effuse, poorly delimited or rarely by a greyish prothallus (never a black prothallus!), to 2-4 cm across, potentially mosaic-forming, whitish, silver-white, pale white-greyish sometimes tinged yellow or olivaceous. Apothecia lirelliform, simple or forked, seldom stellate, in patches, usually numerous and possibly covering almost all the thallus, and mainly the center, can form, if arranged parallel, like "writing lines" or a network of dense meshes, 1-2 x 0.2-0.3 mm long and 0.1-0.15 mm tall, superficial, discs a narrow slit in the middle of lirellae, slit seldom opened, blackish. Ascospores more or less clavate, 3-septate, 14-20 x 3-5 µm according to the literature, 15-18 x 4-5 µm according to our measurements. Pycnidia immersed, black. Thallus C-, K- or seldom K+/- pale yellow, Pd-, hymenium I+ blue. Common, slightly thermophile, on smooth bark of trees.







Opegrapha atra Han sur Lesse 1
Jacques HAINE



Opegrapha atra Han sur Lesse
Jacques HAINE



Opegrapha atra Châteaulin 1
Bernard BOUFFINIER



Opegrapha atra Châteaulin 2
Bernard BOUFFINIER



Arthonia atra Coupe lirelle KOH Belgique 1
Jacques HAINE



Arthonia atra Saint-Fiacre
Michel DAVID



Arthonia atra Saint-Drigent
Michel DAVID



Arthonia atra Asque KOH Belgique 2
Jacques HAINE



Arthonia atra Landévennec
Bernard BOUFFINIER



Arthonia atra Roscanvel
Bernard BOUFFINIER



Arthonia atra Saint-Philibert 1
Bernard BOUFFINIER



Arthonia atra Saint-Philibert 2
Bernard BOUFFINIER



Arthonia atra Stang-Luzigu 1
Bernard BOUFFINIER



Arthonia atra Stang-Luzigu 2
Bernard BOUFFINIER



Arthonia atra Tregarvan
Bernard BOUFFINIER



Arthonia atra Argol
Bernard BOUFFINIER



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