Opegrapha saxigena Roccellaceae
Gyrographa saxigena (Opegrapha saxigena)

Growth type crustose
Chemical results negative. BLS conservation evaluation: LC NS Sc IR

On sheltered, deeply shaded siliceous rocks, especially in old woodlands. Occasional on smooth bark. Can be locally frequent in the SW and West.

Mosaic-forming thin or partially cracked dark-chocolate to deep purplish brown thalli surrounded by a thin dark prothallus. Apothecia are often sparse, short, rarely branched, the disc a persistent slit. Spores 3-septate, (15-)16-20(-22) x 4-5(-6) Ám. Soredia absent. Micrograph below.

Similar: Gyrographa gyrocarpa is sorediate with gyrose apothecia

Opegrapha saxigena

Opegrapha saxigena

Microscope photograph
Opegrapha saxigena
Opegrapha saxigena
On chert. Portland, Dorset. February 2016

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