Strongwellsea caulis, Strongwellsea lata, and Strongwellsea potentia (Entomophthorales: Entomophthoraceae), three new species infecting adult flies (Diptera: Anthomyiidae)

The insect-pathogenic fungal genus Strongwellsea (Entomophthorales) contains specialist species infecting only adult cyclorrhaphan flies with an infection that will usually develop one, two or even three abdominal holes through which conidia are discharged while the fly is still alive. We describe three new species from Strongwellsea infecting adult flies from the family Anthomyiidae. Strongwellsea caulis infects cabbage root fly, Delia radicum, Strongwellsea lata infects Anthomyia liturata, and Strongwellsea potentia infects Hylemya vagans. The descriptions of the three new species are based on 1) pathobiology as revealed by their differing natural host species, 2) the morphologies of primary conidia and resting spores, and 3) their differing by ITS2 sequences. Of particular importance is that the two pest species cabbage fly D. radicum and bean seed fly Delia platura are infected by different species from Strongwellsea, namely S. caulis and Strongwellsea castrans respectively. Our findings suggest the existence of a high but still poorly known diversity of highly specialized Strongwellsea species infecting adult flies from Anthomyiidae that necessitated our emendation of S. castrans to clarify the differences among the species in the complex of anthomyiid pathogens.