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Roccellographa circumscripta (Taylor) Ertz & Tehler morpho circumscripta

Synonyms:

Sclerophytonomyces circumscriptus Sparrius & P. James

Peterjamesia circumscripta (Taylor) D. Hawksw.



Family:

Habitat: Xeric supralittoral  zone

Description

    Thallus crustose, more or less round-shaped, 1-5 cm diam., often mosaic-forming, 0.2-0.25 mm thick, minutely powdery to scurfy surface with dense packed calcium oxalate crystals, rimose-cracked, areole-forming, areoles to 1-2 mm irregular, jagged, pale grey when well fertile, otherwise white-greyish, dull white tinged yellow, grey-yellow, but becoming orange or yellow-orange when eroded or damaged or by scratching owing to the photobiont (Trentepohlia), prothallus distinct, slightly torn, blackish. Apothecia to 0.1 mm, immersed in the thallus, visible as small black dots, disc flat, black, white, powdery. Ascopores elongate, brownish when mature, (4) 5 (7)-septate, 17-25 x 5-6 µm. C-, K-, KC+ pale yellow, Pd+ yellow-orange. Common on rocky shores, under dry overhangs of siliceous rocks protected from direct light and rain. Highly variable species (several taxa may exist), with an Enterographa aspect sometimes in association with Roccellographa (Peterjamesia) sorediata, but the two species have different overall colours: Peterjamesia circumscripta is in average greyish whitish-yellowish and Roccellographa (Peterjamesia) sorediata  is pale greyish tinged blue. May form conspecific mosaics or with Roccellographa (Peterjamesia) sorediata.. Sometimes associated with Arthonia endlicheri, and close to Cliostomum tenerum, Llimonea sorediata, Dirina massiliensis f. sorediata in areas better lit. Arthonia atlantica is very similar in the field, but K+ yellow, Pd+ pale yellow or pale red, but not yellow-orange but without orange when scratched. However, all intermediate specimen between these two species may be found, based on field observation and chemical spot tests. Additional studies would be required in order to clarify the issue.







Peterjamesia circumscripta Pointe du Van 1
Alain GERAULT



Peterjamesia circumscripta et sorediata Pointe du Van
Alain GERAULT



Peterjamesia circumscripta Cap de la Chèvre 1
Bernard BOUFFINIER



Peterjamesia circumscripta Cap de la Chèvre 2
Bernard BOUFFINIER



Peterjamesia circumscripta Pen Hir 1
Bernard BOUFFINIER



Peterjamesia circumscripta Habitat Crozon 2
Bernard BOUFFINIER



Peterjamesia circumscripta Habitat Crozon 3
Bernard BOUFFINIER



Peterjamesia circumscripta Habitat Crozon 1
Bernard BOUFFINIER



Peterjamesia circumscripta avec Arthonia atlantica Pointe du Van 3
Bernard BOUFFINIER



Roccellographa circumscripta morpho. circumscripta Crozon Kernaou 1
Michel DAVID



Roccellographa circumscripta morpho. circumscripta Crozon Kernaou 2
Michel DAVID



Roccellographa circumscripta morpho. circumscripta Crozon Kernaou 3
Michel DAVID



Roccellographa circumscripta morpho. circumscripta Crozon Kernaou 4
Michel DAVID



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