The Norwegian species of Hypoxylon have been treated with respect to their ecology, morphology and taxonomy. Their host trees have been identified and percentage frequency of each host and substrate type (bark/wood) calculated. Ecologically the species are grouped according to their saprobic ability, and to their preferred hosts and substrates (bark or wood). From a chorological point of view the species are grouped into three different geoelements according to the distributional centre for each species in Norway, thereby also taking into consideration the total Nordic distribution. Complete locality lists for each species are given and a key to all Nordic species is presented.
Twelve species of Hypoxylon have so far been recognized in Norway: Hypoxylon cercidicola, H. cohaerens, H.fragiforme, H.fuscum, H. howeianum, H. laschii, H. macrosporum, H. multiforme, H. porphyreum, H. rubiginosum, H. salicicola and H. vogesiacum. Two species belong to Hypoxylon sect. Annulata: Hypoxylon cohaerens and Hypoxylon multiforme, the remainder belong to Hypoxylon sect. Hypoxylon. Two new species are described: H. porphyreum and H. sa/icicola. In a previous treatment of Nordic species of Biscogniauxia and Hypoxylon, Hypoxylon cercidicola and H. salicico/a were included in and reported as H. rubiginosum and H. rutilum, respectively, while H. porphyreum was included in H. juscum. Hypoxylon macrosporum and H. laschii, by several authors considered as varieties of H. vogesiacum and H. rubiginosum, respectively, are treated as species.
