Pandora formicae, a specialist ant pathogenic fungus: New insights into biology and taxonomy

Among fungi from the order Entomophthorales (Entomophthoromycota), there are many specialized, obligatory insect-killing pathogens. Pandora formicae (Humber & Bałazy) Humber is a rare example of an entomophthoralean fungus adapted to exclusively infect social insects: wood ants from the genus Formica. There is limited information available on P. formicae; many important aspects of this host-pathogen system remain hitherto unknown, and the taxonomical status of the fungus is unclear. Our study fills out some main gaps in the life history of P. formicae, such as seasonal prevalence and overwintering strategy. Field studies of infection prevalence show a disease peak in late summer and early autumn. Typical thick-walled entomophthoralean resting spores of P. formicae are documented and described for the first time. The proportion of cadavers with resting spores increased from late summer throughout autumn, suggesting that these spores are the main overwintering fungal structures. In addition, the phylogenetic status of Pandora formicae is outlined. Finally, we review the available taxonomical literature and conclude that the name P. formicae should be used rather than the name P. myrmecophaga for ant-infecting fungi displaying described morphological features.