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Racodium rupestre Pers.
Family: Racodiaceae
[Cystocoleus rupestris (Pers.) Rabenh.,  more]
Racodium rupestre image
Stephen Sharnoff  

Global occurrence: Oceania – Australasia | Eurasia – Europe | Americas – North America (incl Mexico) | Arctic.  Life habit: lichenized (mutualistic with algal photobionts).  Thallus: filamentose (filamentous), pannose; [th] upper surface: black(ish) | black(ish) brown; [th marginal and upper surface] specific structures: absent.  Ascomata: absent.  Secondary metabolites: absent.  Primary photobiont: present, chlorophytaceous – trentepohliaceous, trentepohlioid.  Secondary photobionts (eg in cephalodia): absent.