Incompatibility Systems, Cultural Features and Species Circumscriptions in the Ectomycorrhizal Genus Laccaria (Agaricales)

Data from sexual incompatibility and cultural studies were used to further elucidate the biology and taxonomy of species of Laccaria. Six intersterility groups, representing five species, were recorded in 47 Swedish collections by pairing tests among monosporous isolates. In the secondarily homothallic L. altaica the pairings were made with monokaryotic mycelia produced by dedikaryotization. Laccaria altaica, L. amethystina, L. bicolor, and L. proxima each comprised one intersterility group, while members of two groups were referable to L. laccata sensu stricto. Intrastock pairing tests with three species showed a bifactorial (tetrapolar) incompatibility system. In only three of 11 cases analyzed, however, were all four mating type factors found. Each of the species could be further characterized by their growth rate, cultural morphology, and early growth pattern of the primary mycelium. Nutritional tests showed no differences in vitamin requirements for the five species studied. However, L. bicolor responded differently to some complex additives.