Alien fungal species distribution: the study case of Favolaschia calocera.

Invasive organisms (especially plants and animal species) are considered to be one of the main causes of global biodiversity loss. Up to now, few papers have dealt with the spreading of fungi. The establishment of the geographic origin of alien organisms could be useful to assess their impact on the environment. Favolaschia calocera is a basidiomycete species which was first described from Madagascar, and successively observed in New Zealand in 1969, where it has currently been recorded in more than 200 stands. It has recently also been reported in Australia, Thailand, China, Kenya, and Reunion Island. F. calocera was found in Genoa, Italy, in 1999: this recording represented the first in Europe. Till now, Favolaschia specimens have been collected in six areas around Genoa. F. calocera was observed growing on debris of various vascular plant species (Pteridophytes, Conifers, Mono- and Dicotyledons), thus showing to be a polyphagous species. Because it is spreading, it needs to be monitored. The main goal of our research is to investigate, through molecular phylogeographic analysis, the origin of the Italian strains. The sequencing of the ribosomal DNA ITS region of the Italian specimens followed by Neighbour-joining analysis showed that they cluster with the specimens from New Zealand, Kenya, Norfolk Island and Réunion Island. Hypotheses on the origin and introduction way as well as on its mechanisms of spreading are provided.