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Placopyrenium trachyticum  (Hazsl.) Breuss

Synonyms:

Dermatocarpon trachyticum  (Hazsl.) Vain.



Family: VERRUCARIACEAE

Habitat: Ubiquitous

Description

    Thallus squamulose, squamules flat, 1-1.5 mm across, crowded and almost with contiguous free edges, squamules margins black producing an overall areolate aspect, very pale brown-grey, covered with a grey-whitish pruine, overall aspect grey-whitish, ash grey, prothallus black. Perithecia totally immersed within the thallus, hardly visible as dark dots, 1-5 (10) per squamule. Ascospores broadly ellipsoid, colourless, simple, 13-20 x 5-7.5 µm. Photobiont: Chlorophyceae. Chemical spot tests negative. Rare, on calcareous rocks or mortar of walls in nutritent-rich zones. N.B. This species would be parasitic, at least at the beginning of its development, of Verrucaria and notably of Verrucaria nigrescens. Very similar to Placopyrenium fuscellum (and sometimes ranked as p.p. by some authors) parasite of Aspicilia calcarea.







Placopyrenium trachyticum Argonne 1
Jacques HAINE



Placopyrenium trachyticum Argonne 2
Jacques HAINE



Placopyrenium trachyticum Argonne 3
Jacques HAINE



Placopyrenium trachyticum Asque et photobionte dans l'eau Argonne 4
Jacques HAINE



Placopyrenium trachyticum Spores dans le rouge Congo Argonne 5
Jacques HAINE



Placopyrenium trachyticum Spores et photobionte dans l'eau Argonne 6
Jacques HAINE



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