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Petractis luetkemuelleri (Zahlbr.) Vezda

Synonyms:

Gyalecta luetkemuelleri  Zahlbr.



Family: STICTIDACEAE

Habitat: Ubiquitous

Description

    Thallus crustose, thin and coating the substrate, minutely rugose, presence of minute sinuous whitish veins (calcite?), grey-pink, pink, dull whitish-pink, pale salmon (only when fresh, otherwise white-greyish, pale ochre-greyish, pale greyish), margin undeterminate, prothallus absent or undeterminate. Apothecia sometimes numerous, totally or to 3/4th immersed in the thallus, 0.4-0.5 mm diam., disc concave to flat, beige-pink when fresh, or ochraceous, pale brown-yellowish, pale brown, exciple thick, petal-shaped at first, more or less wraping the disc, whitish. Ascii 8-spored, 100-120 x 10-14 µm. Ascospores highly variable, ellipsoid, colourless, wraped into a perispore (halo-forming but sometimes hardly visible), in general transversally 3-septate, but possibly 4-5-septate or even muriform owing to a longitudinal septum, 18-30 x 7-10 µm. Photobiont: Trentepohlia sometimes forming orange spots visible in eroded sections of the thalli or even free in old specimen. Thermopilic and Mediterranean species, very rare in our propection area, restricted to well-lit vertical walls of hard limestone rocks near the seashore. N.B. In the same sites but on more soft and humid limestones a slightly different but inconspicuous morph may be found,  Ramonia calcicola, with smaller apothecia, a more rugose or granular thallus with more or less pink tinges. See also Petractis clausa of which apothecia are much larger, ascospores strictly 3-septate and photobiont different (Scytonema).







Petractis luetkemuelleri Avec thalle rose sur roche calcaire dure Crozon S1
Bernard BOUFFINIER



Petractis luetkemuelleri Avec Caloplaca lactea grp. sur roche calcaire dure Crozon S2
Bernard BOUFFINIER



Petractis luetkemuelleri Avec thalle rose sur roche calcaire dure Crozon S3
Bernard BOUFFINIER



Petractis luetkemuelleri Sur roche calcaire dure Crozon S4
Joƫl QUERELLOU



Petractis luetkemuelleri Avec photobionte orangƩ Ơ Trentepohlia visible Crozon S5
Joƫl QUERELLOU



Petractis luetkemuelleri Avec photobionte orangƩ Ơ Trentepohlia visible Crozon S6
Joƫl QUERELLOU



Petractis luetkemuelleri Vieux thalle sur roche calcaire dure Crozon S7
Joƫl QUERELLOU



Petractis luetkemuelleri Vieux thalle sur roche calcaire dure Crozon S8
Joƫl QUERELLOU



Petractis luetkemuelleri Asque Lugol Crozon S9
Jacques HAINE



Petractis luetkemuelleri Asque Bleu Coton Crozon S10
Jacques HAINE



Petractis luetkemuelleri Spores eau Crozon S11
Jacques HAINE



Petractis luetkemuelleri Asque Eau Crozon S12
Jacques HAINE



Petractis luetkemuelleri et Trentepohlia libre Crozon S13
Bernard BOUFFINIER



Petractis luetkemuelleri Avec Catillaria lenticularis Crozon S14
Bernard BOUFFINIER



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