The type was collected in 1846 by Ronald Campbell Gunn from Penquite at Launceston, Tasmania, where it was growing on the bark on a young Eucalyptus amygdalina tree.

[4] The taxon has been shuffled to several genera in its taxonomic history, including Marasmius, Pleurotus, and the now-superseded genus names Chamaeceras, and Dendrosarcus.

In 1970, Rolf Singer first suggested that this species was lichenised, noting its association with a crustose lichen on Eucalyptus saplings in Australia.

[3] Singer later provided more detailed observations in 1973, describing a crustose organism consisting of Coccomyxa algal cells embedded in basidiomycete hyphae, which produced fruiting bodies identified as Marasmiellus affixus (now C. affixa).

[3] In Tasmania (Australia), Collybiopsis affixa grows in sclerophyll forest, on dead woody material, especially that which has lost its bark.