Scoliciosporum umbrinum forme parasite de Rhizocarpon geographicum s.l.

     Scoliciosporum umbrinum can sometimes (at least in its youth) behave as a parasite of certain crustose lichens and in particular of Rhizocarpon geographicum s.l. It can then only be differentiated from Scoliciosporum intrusum, which is always parasitic, only by microscopic examination, the latter species having spores smaller and 1-(3)-septate.