Circinotrichum olivaceum (Speg.) Piroz presents setae erect, circinate, unbranched, verrucose, conidiophores micronematous, flexuous, subhyaline to pale brown, smooth, conidiogenous cells polyblastic, discrete, percurrent, obclavate to lageniform, colourless and conidia forming a whitish layer at the base of setae, cylindrical to fusiform, straight or slightly curved, aseptate, hyaline, smooth (Pironzynski, 1962; Ellis, 1971).

Circinotrichum olivaceum is known from several countries around the world, but always related to decomposing plant material. Therefore, it could be considered of least concern.

Distribution: subtropical and tropical regions

Currently the genus comprises 21 species. Circinotrichum olivaceum is common in the tropics leaf litter decomposing in the forest floor (Pirozynski 1962, Sutton 1980, Mercado-Sierra 1984, Grandi; Silva 2006). There is also record in aquatic environment, in Australia (Hyde 1997).

This species is collected associated with leaf litter.

None

There is no report of this species in the deserts of the world and Antarctica. In Brazil, there is no record in the cerrado, rupestrian fields, ecosystems associated with the Atlantic rainforest such as tableland, sandbanks and mangroves.