Spruce associated Porodaedalea species distribution in Sweden

Abstract: Wood-inhabiting fungi have very important roles in the ecosystem in the degradation of dead wood by acting respectively as parasites and saprotrophs in boreal forests. Porodaedalea chrysoloma is a wood-decay parasite poroid fungi that is considered a key species in the old growth boreal forests. Due to forestry its habitat is declining. As consequence since 2020 it has been classified as a near threatened species in the Swedish Red List. Consequently, the overall goal is to create a conservation project for the species in Sweden. But to do this, there are first some issues that need to be solved. The aim of this project is to solve the misidentification between P. chrysoloma and its sister species P. laricis in Sweden and to find out how common is P. laricis in Sweden. I also want to locate the distribution of both species in the country. First it is necessary to determine if the name P. laricis recognized in Sweden and the name P. abietis used in Norway and Finland are synonyms for the same species or if instead they represent two different species. Additionally, another aim is to prepare the samples for a future population genomic study for these two species. Species identification was performed using sequences of the internal transcribed spacer (ITS) region of the nuclear ribosomal DNA. Based on sequence analysis we conclude that P. laricis and P. abietis are synonyms that refer to the same species and that the oldest name and the recommended name that Dyntaxa, the Swedish taxonomic database, should use in its records is P. abietis. Our results show that 85% of the samples sequenced are identified as P. abietis, 15% are identified as P. chrysoloma. Furthermore, P. abietis is concentered in the north of Sweden while P. chrysoloma main distribution is in the south. In addition, this study identified morphological characters that can be used to differentiate between P. chrysoloma and P. abietis.