Prosthemium betulinum and Pleomassaria siparia are found in the same sites
on birch branches. Single spore cultures of P. siparia produced conidia sim
ilar to those of P. betulinum. Restriction analysis of 18S rDNA did not dif
ferentiate between P. betulinum and P. siparia. Random amplified microsatel
lite fingerprints showed a high amount of variation, which was not explaine
d by the origin of cultures. We conclude that P. betulinum is the anamorphi
c state of P. siparia.