Integrative taxonomy of Metarhizium anisopliae species complex, based on phylogenomics combined with morphometrics,...

Metarhizium anisopliae (Clavicipitaceae, Hypocreales) is a globally distributed entomopathogenic fungus, which has been largely studied and used in agriculture for its potent entomopathogenicity. Since its taxonomic establishment as a member of Metarhizium, many closely related taxa have been described with highly similar morphology (cryptic species). A holotype specimen of M. anisopliae is not extant, and the ex-neotype strain (CBS 130.71) does not form a monophyletic clade with other strains, up to now, recognized as M. anisopliae sensu stricto. In this study, we have conducted an integrative taxonomic treatment of M. anisopliae sensu lato by including the ex-neotype strain of M. anisopliae, other unknown strains from our collections identified as M. anisopliae s. lat., as well as other known species that have been previously delimited as closely related but distinct to M. anisopliae. By including whole-genome sequencing, morphometric analysis, LC-MS based metabolomics, and virulence assays, we have demonstrated that M. anisopliae s. str. should also include M. lepidiotae (synonym), and that M. anisopliae s. str. differentiates from the other species of the complex by its metabolome and less severe entomopathogenicity. New taxa, namely M. hybridum, M. neoanisopliae and M. parapingshaense spp. nov., are proposed. The novel taxa proposed here have strong phylogenomics support, corroborated by fine-scale differences in the length/width of conidia/phialides, while the metabolomics and virulence data still largely overlap. We have also demonstrated via population genomics data the existence of local clonal lineages, particularly the one corresponding to the persistence of a biocontrol candidate strain that has been used in the field application for three years. This study showcases the utility of combining various data sources for accurate delimitation of species within an important group of fungal biocontrol agents against pest insects.