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Rhizocarpon reductum Th. Fr.

Synonyms:

Rhizocarpon obscuratum auct. pp.



Family: RHIZOCARPACEAE

Habitat: Ubiquitous

Description

    Thallus crustose, rather thin, small, to 1-2 cm across but able to cover large surfaces by conspecific colonies confluence, cracked, areolate, areoles 0.2-0.4 mm across, flat to slightly convex, grey, grey-brownish, prothallus black, more or less developed at the margin, larger when shaded. Apothecia innate to slightly sessile, 0.4-0.8 mm diam., disc flat to a little convex at first then markedly convex when mature, rough, black, exciple persistent, thick, black. Ascopsores ellipsoid, muriform, 20-35 x 10-15 µm. Photobiont: ChlorococcoidC-, K+ yellow, Pd+ orange ; seldom K-, P- or K+ red, Pd+ orange. Not especially maritime, but rather common on large pebbles and siliceous rocks. Exceptionally variable and several ecotypes have been described and among them some more specifically maritime. N.B. Easy to confused with  Fuscidea cyathoides (Pd+ red) and with species belonging to the Buellia aethalea  group (K+ yellow > red) and sometimes found  mixed together, requiring an observation of mature ascospores to be distinguished. Additionally, not to be confused with Rhizocarpon richardii that is darker with violet tinge and with Rhizocarpon petraeum on calcareous rocks, of which  the thallus is thinner, less dark and more whitish, not cracked up to the margin and with a less developed prothallus.*







Rhizocarpon reductum Menez Meur 1
Bernard BOUFFINIER



Rhizocarpon reductum Brest
Alain GERAULT



Rhizocarpon reductum Térénez
Alain GERAULT



Rhizocarpon reductum Coadry 1
Bernard BOUFFINIER



Rhizocarpon reductum Coadry 2
Bernard BOUFFINIER



Rhizocarpon reductum var. Sur la face verticale d'un rocher de grès armoricain Lanvéoc
Bernard BOUFFINIER



Rhizocarpon reductum Crozon 1
Bernard BOUFFINIER



Rhizocarpon reductum Crozon 2
Bernard BOUFFINIER



Rhizocarpon reductum var. Pointe du Van
Bernard BOUFFINIER



Rhizocarpon reductum Monthermé
Jacques HAINE



Rhizocarpon reductum Asque Monthermé 2
Jacques HAINE



Rhizocarpon reductum Spores Monthermé 3
Jacques HAINE



Rhizocarpon reductum Sur galet Pointe de Dinan 1
Michel DAVID



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