Genetic variation within the cosmopolitan aquatic fungus Lignincola laevis (Microascales, Ascomycota)

Recent estimates suggest that there are as many as 10,000 marine fungal species, although the current number stands at just over 500. Previous studies were predominantly surveys of marine fungal diversity on various substrata in Europe, north American and Asia, while little research exists on the possible processes leading to their current distribution. Therefore, this study was initiated to assess the genetic structure and geographical distribution of the cosmopolitan aquatic fungus Lignincola laevis. The internal transcribed spacers and partial 28S region of the rRNA gene clusters, and the partial MCM7 protein gene were sequenced and analysed using maximum parsimony and Bayesian likelihood methods. Three distinct lineages were present in the sampled L. laevis isolates with a mean pairwise distance between the groups > 10 %. However, no geographical assemblages could be identified in the phylogeny. The high genetic divergence suggests that Lignincola laevis is a species complex that consists of a group of closely related species with subtle morphological differences. The lack of geographical structure in the sampled isolates of L. laevis may suggest a high dispersal capacity for L. laevis.