Global diversity analysis of plant-associated <i>Pseudopithomyces</i> fungi reveals a new species producing the toxin associated with facial eczema in livestock: <i>Pseudopithomyces toxicarius sp. nov</i> .

Facial eczema (FE) in ruminants is associated with the fungal toxin sporidesmin that can cause significant mortality in grazing livestock. Incidences are particularly severe in New Zealand but are reported worldwide. The syndrome has historically been attributed to Pithomyces chartarum , a species transferred to Pseudopithomyces Pithomyces taxonomy of Pseudopithomyces concatenated protein coding genes distinguished 15 species in the genus. We describe Pseudopithomyces toxicarius sp. nov. as a novel sporidesmin Pse. chartarum , with 80 % of isolates in this study able to produce the toxin. Two Pithomyces species are combined into Pseudopithomyces as Pseudopithomyces cynodontis comb. nov . and Pseudopithomyces pavgii comb. nov . We also place Pseudopithomyces pandanicola in synonymy with Pseudopithomyces palmicola. Pithomyces terricola Longipedicellataceae as Pseudoxylomyces terricola comb. nov . Pseudopithomyces chartarum was the only other species where sporidesmin was detected, but this was found in only one of 14 isolates we tested. The extent of sporidesmin synthesis in this genus remains to be determined due to the limited availability of strains for testing in other species. Pse. toxicarius , Pse. chartarum and Pse. palmicola revealed distinct genetic subclades within each species. Four species were detected in New Zealand. Pseudopithomyces toxicarius and Pse. chartarum Pse. palmicola Pseudopithomyces suggesting widespread global distribution.