ITS-based assessment of Madagascar's fungal diversity and arrival of EcM fungi to the island

Madagascar is known for its high diversity and endemism of Fauna and Flora, which makes it particularly interesting for research on diversity and evolution. Fungi, however, have been largely overlooked, and whether fungi exhibit the same patterns as animals and plants has yet to be further examined. We collected fungal sporocarps and ectomycorrhizal (EcM) roots during opportunistic surveys in five forests in Madagascar and generated a dataset of fungal Internal Transcribed Spacer (ITS) DNA sequences. We analysed them together with all publicly available fungal ITS DNA sequences. We identified 620 Operational Taxonomic Units (OTUs) from Madagascar, 10% of which contained only sequences from our surveys. We found 292 OTUs belonging to EcM species with /russula-lactarius, /boletus, /tomentella-telephora, /cortinarius and /amanita as the most abundant EcM lineages. Overall, sixty percent of all the fungi and 81% of the EcM species found are endemic to Madagascar. Lastly, we conducted a phylogenetic analysis using all the OTUs in Amanitaceae, Boletaceae and Russulaceae families to elucidate their relative timing of arrival in Madagascar. We found that the EcM species from Madagascar in the three families diverged recently (less than 34 mya), long after the separation of India and Madagascar (88 mya), which is consistent with a dispersal mediated process of arrival on the island. Our study provides the first comprehensive view of the current state of knowledge of EcM fungi in Madagascar represented by molecular data useful for ecological and evolutionary studies.