Seagrasses, seaweeds and plant debris: An extraordinary reservoir of fungal diversity in the Mediterranean Sea

This review gathers data derived from many research efforts on marine fungi associated with plant-origin substrates in the Mediterranean Sea. Overall, the review draws up a list of 378 taxa associated with seagrasses, seaweeds and wood. For each of the three substrates, on average, 92.7% of the taxa belonged to the phylum Ascomycota. Basidiomycota were better represented in seagrasses (9.8%) than in seaweeds (4.9%) and wood (1.2%). Mucoromycota and Mortirellomycota were scarce, while Chytridiomycota was detected only in association with phanerogames (3.7%). Dothideomycetes and Sordariomycetes were the dominant classes, while the orders Pleosporales and Hypocreales were significantly represented in the three sububstrates (42, 37, 10 taxa-30, 40, 16 taxa). Seagrasses with 210 associated taxa were the substrates with the richest fungal communities, immediately followed by seaweeds (180 taxa) and finally by wood (78 taxa). Out of the total, only 12 taxa were shared by the three varieties of substrates, including species that were widespread in marine environments. However, many algal species and seagrasses inhabiting the Mediterranean Sea remain unexplored. This gap indicates the need to apply more extensive surveys to explain the huge fungal biodiversity herein hosted, and increase the chances of describing novel fungal lineages.