Paecilomyces is a genus of fungi. A number of species in this genus are plant pathogens. Several of the entomopathogenic species, such as "Paecilomyces fumosoroseus" have now been placed in the genus Isaria, in the order Hypocreales and family Cordycipitaceae. In 1974, R.A. Samson transferred the nematicidal species Paecilomyces lilacinus to this genus. However, publications in the 2000s (decade) indicated that the genus Paecilomyces was not monophyletic, and the new genus Purpureocillium was created to hold the taxon which includes P. lilacinum: with both parts of the name referring to the purple conidia produced by the fungus.

Species

Traditionally, Paecilomyces held strictly asexual species and later housed numerous anamorphic forms of fungi with their teleomorph described to a separate genus. From 41 described species in 2000 and over 100 known combinations in this genus, the amount of species in Paecilomyces reduced to 10 described species in 2020 following the adaptation of the "one fungus one name" rule. incertae sedis Ascomycota