Pleomassaria siparia is composed of two biological species, both of which occur in dead twigs of Betula pendula and B-pubescens

The coelomycetes Prosthemium betulinum, Pr. asterosporum and the ascomycete Pleomassaria siparia are all common in the basal part of detached birch twigs in Finland. The teleomorph of Pr. betulinum is Pl. siparia, but the teleomorph of Pr. asterosporum is unknown. In denaturing gradient gel electrophoresis (DGGE) analysis, different internal transcribed spacer (ITS) alleles were observed among Pr. betulinum and Pr. asterosporum isolates. Both alleles were also observed among Pl. siparia isolates. We developed specific markers, which separated between Pr. betulinum and Pr. asterosporum. The alleles in these loci correlated to ITS alleles among Pl. siparia isolates. Thus we showed that Pl. siparia is composed of two separate biological species indistinguishable by teleomorph morphology, although they correlate to anamorphic species Pr. betulinum and Pr. asterosporum The in vivo studies with specific primers showed that both of these two species occur in dead twigs of Betula pendula and B. pubescens.