Patterns of coevolution between ambrosia beetle mycangia and the , with five new fungal genera and seven new species.

Ambrosia beetles farm specialised fungi in sapwood tunnels and use pocket-like organs called mycangia to carry propagules of the fungal cultivars. Ambrosia fungi selectively grow in mycangia, which is central to the symbiosis, but the history of coevolution between fungal cultivars and mycangia is poorly understood. The fungal family previously included three ambrosial genera (, , and ), each farmed by one of three distantly related tribes of ambrosia beetles with unique and relatively large mycangium types. Studies on the phylogenetic relationships and evolutionary histories of these three genera were expanded with the previously unstudied ambrosia fungi associated with a fourth mycangium type, that of the tribe . Using ITS rDNA barcoding and a concatenated dataset of six loci (28S rDNA, 18S rDNA, 1-α, , , and ), a comprehensive phylogeny of the family was developed, including gen. & sp. nov., a non-ambrosial species that is closely related to the family. Three minor morphological variants of the pronotal disk mycangium of the were associated with ambrosia fungi in three respective clades of : gen. nov., gen. nov., and sp. nov. Closely-related species that are not symbionts of ambrosia beetles are accommodated by gen. & comb. nov. and gen. & comb. nov. The divergent morphology of the ambrosial genera and their phylogenetic placement among non-ambrosial genera suggest three domestication events in the . Estimated divergence dates for the ambrosia fungi and mycangia suggest that mycangia may have been the first to acquire symbionts and other ambrosial fungal genera emerged shortly after the evolution of new mycangium types. There is no evidence of reversion to a non-ambrosial lifestyle in the mycangial symbionts.