A cellulolytic fungus that is very closely related to Stachybotrys sp. Both fungi have a worldwide distribution and are often found together and are commonly found in soil. Recent studies on mycotoxins revealed that Memnoniella echinata can have a toxicity similar to that of some isolates of Stachybotrys chartarum. Both produce varying amounts of simple trichothecenes. Thus, it is suggested that Memnoniella sp. should also be considered potentially dangerous in indoor air. The major difference between the two fungi is that the conidia of Memnoniella sp. are in long persistent chains while those of Stachybotrys are aggregated in slimy heads. Also the aerodynamic diameter of Memnoniella sp. conidia is smaller and it would be expected to have an even greater potential to penetrate deep into lungs than the conidia of Stachybotrys sp.