Multigene phylogeny reveals new lineage for Stachybotrys chartarum, the indoor air fungus

Stachybotrys chartarum is an asexually reproducing fungus commonly isolated from soil and litter that is also known to occur in indoor environments and is implicated as the cause of serious illness and even death in humans. Despite its economic importance, higher level phylogenetic relationships of Stachybotrys have not been determined nor has a sexual state for S. chartarum been reported. DNA sequences from four nuclear and one mitochondrial gene were analyzed to determine the ordinal and familial placement of Stachybotrys within the Euascomycota. These data reveal that species of Stachybotrys including S. chartarum, S. albipes for which the sexual state Melanopsamma pomiformis is reported, species of Myrothecium and two other tropical hypocrealean species form a previously unknown monophyletic lineage within the Hypocreales. These results suggest that Stachybotrys and Myrothecium are closely related and share characteristics with other hypocrealean fungi. In addition, S. chartarum may have a sexual state in nature that consists of small, black, fleshy perithecia similar to Melanopsamma.