|Pyrenochaeta species comprise a small proportion of the fungal biota and is closely related to Phoma. This genus is a pycnidial former although many times pycnidia are lacking and the organism appears only as sterile mycelia. May be identified on tape lifts and tease mounts from bulk samples if the pycnidia are present. (Pycnidial formers may have little effect on the indoor air because the spores are not readily disseminated by air currents.) Very rarely isolated from air by culturable (Andersen) sampling. (Spores do not have distinctive morphology and would be categorized as "other colorless" on spore trap samples.) Natural habitat is plant debris and soil in tropical countries, where it is a cause of mycetoma. No information is available regarding toxicity. Allergenicity has not been studied.