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Petractis clausa (Hoffm.) Kremp.

Synonyms:

Gyalecta exanthematica (Sm.) Nyl.

Gyalecta exanthemica (Sm.) Fr.



Family: STICTIDACEAE

Habitat: Ubiquitous

Description

    Thallus endolithic, sometimes hardly visible, dull whitish, pale yellow-ochraceous. Apothecia more or less immersed in the substratum (and sometimes leaving a minute depression when falling down), 0.5-1 mm diam., disc pink-orange, pale orange, flat or concave, at first entirely covered with exciple that opens like mechanical claws with 4-8 radiating cracks star-shaped, determining an irregular exciple more or less persistent. Ascospores narrowly ellipsoid, 3-septate, 18-30 x 7-10 µm, surrounded by a well-developed gelatinous perispore that under microscope and after rehydration is crew-cut like or bottle-brush-shaped. Photobiont: cyanobacteria: Scytonema. Chemical spot tests negative. Rare, on vertical walls of hard calcareous rocks. N.B. Petractis luetkemuelleri is a very similar species but with smaller apothecia and a different photobiont: Trentepohlia.







Petractis clausa Dr么me proven莽ale 1
Jacques HAINE



Petractis clausa Dr么me proven莽ale 2
Jacques HAINE



Petractis clausa Dr么me proven莽ale 3
Jacques HAINE



Petractis clausa Dr么me proven莽ale 4
Jacques HAINE



Petractis clausa Asque Melzer Dr么me proven莽ale 5
Jacques HAINE



Petractis clausa Spore Eau Dr么me proven莽ale 6
Jacques HAINE



Petractis clausa Spores Eau Dr么me proven莽ale 7
Jacques HAINE



Petractis clausa Provence Oppedette 1
Bernard BOUFFINIER



Petractis clausa Provence Oppedette 2
Bernard BOUFFINIER



Petractis clausa Provence Oppedette 3
Bernard BOUFFINIER



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