A new lichen and lichenicolous fungus from Larix laricina in patterned fens of boreal North America

Calicium poculatum and Ramboldia canadensis are described as new species occurring on Larix laricina. Calicium poculatum, currently known from four Canadian provinces and the US state of Minnesota, is characterized by its short-stalked black ascomata, short ascospores and occurrence as a parasite on Lecanora caesiorubella subsp. saximontana. Based on DNA sequence data, its nearest relative is the likewise parasitic Calicium episcalaris. Ramboldia canadensis, currently known only from dead wood of Larix laricina snags in Canada, engages in a fully developed lichen symbiosis with Trebouxia simplex and is characterized in statu symbiotico by having a rimose to verrucose-areolate, greyish creamy sorediate thallus with dark brown to blackish soredia that begin on the margins, and the occurrence of a secondary metabolite similar to barbatolic acid. Phylogenetic analysis recovers it as sibling to a clade of the genus heretofore known only from the Southern Hemisphere and the lower latitudes of the Northern Hemisphere. We also report Lecidella xylophila as new to North America.