ABSTRACT: Ascosphaera torchioi sp. nov. differs from other described Ascosphaera by having larger spores, and by having residual bodies that are present within and between the spore balls, and also on the inner wall of ascocysts. The fungus was found in mummified larvae of Osmia lignaria propinqua, a pollinator of orchard crops. The fungus induces symptoms characteristic of those Ascosphaera species that form ascocysts beneath the integument. Experimentally, A. torchioi was found to be pathogenic to O. lignaria and O. californica. Only germination of spores and minimal hyphal growth could be obtained on artificial culture media.

KEYWORDS: Ascosphaera torchioi sp. nov., Ascomycota, Ascosphaeraceae, Osmia lignaria propinqua, Chalkbrood Disease

NOMENCLATURAL NOVELTIES:
Ascosphaera torchioi Youssef & McManus, p. 9