Polyozellus marymargaretae was described from a type collection made in Washington, USA (Voitk et al. 2017). Before that, it has long been referred to as P. multiplex; a species complex of at least five distinct species (Voitk et al. 2017).

Polyozellus marymargaretae is an uncommon species of 'Blue Chanterelle' from old growth forests in the Pacific Northwest. Long referred to by the name P. multiplex, which is now known to be a species complex of at least five distinct species, P. marymargaretae is currently known from ~five localities in the Cascade Range and Olympic mountains plus one record in Vancouver Island, British Colombia, in mature and old growths forests; a habitat in decline. It may be restricted to mature and old growth forests. Suitable habitat which is now rare and fragmented and continuing to decline in both quality and geographic extent. The scarcity of remnant old growth and mature forests in the Cascade Range, and their fragmented condition are a major cause for concern; it is unknown if this species is capable of colonising and persisting in younger forests. Steel et al. (2023) calculated that over 30% of the conifer forests in the southern Sierra Nevada Mountains transitioned to non-forest vegetation between 2011-2020 and that between 50-85% of mature forests significantly declined in quality during this time. Extrapolating these data to forests of the Pacific Northwest yields a conservative estimate of a loss / decline of at least 30% of habitat for this species over the past three generations (50 years) and this is continuing into the future. It is suspected that the population of this species will be declining at a similar rate. Therefore, it is assessed as Vulnerable A2c+3c+4c.

Polyozellus marymargaretae is currently known from Oregon and Washington, USA and one record from Vancouver Island, British Colombia (Voitk et al. 2017, MyCoPortal 2024).

Polyozellus marymargaretae is currently only known from ~five localities in the Cascade Range and Olympic mountains plus one record in Vancouver Island, British Colombia, in mature and old growths forests; a habitat in decline. However, data to confidently assess overall population size and trends are challenging, in part due to all collections of Polyozellus being called P. multiplex pre-2017. This species may be restricted to mature and old growth forests. Suitable habitat which is now rare and fragmented and continuing to decline in both quality and geographic extent. The scarcity of remnant old growth and mature forests in the Cascade Range, and their fragmented condition are a major cause for concern; it is unknown if this species is capable of colonising and persisting in younger forests. Steel et al. (2023) calculated that over 30% of the conifer forests in the southern Sierra Nevada Mountains transitioned to non-forest vegetation between 2011-2020 and that between 50-85% of mature forests significantly declined in quality during this time. Extrapolating these data to forests of the Pacific Northwest yields a conservative estimate of a loss / decline of at least 30% of habitat for this species over the past three generations (50 years) and this is continuing into the future. It is suspected that the population will be declining at a similar rate.

Polyozellus marymargaretae is an ectomycorrhizal species, associated with conifers in mature and old growth forests of the Pacific Northwest mountains. Voitk et al. (2017) report "on soil in moss under old growth Abies grandis, Pseudostuga menziesii, and Picea engelmannii". Fruiting is from late summer or early fall; with sporocarps long-lasting and typically persisting until there is a deep freeze.

Polyozellus marymargaretae is an ectomycorrhizal fungus species dependent on living host trees for viability. The major threats to this species and its co-occurring co-generic taxa are habitat destruction via the logging of old-growth forests to which it appears confined to and an increase in fire frequency and intensity. The extent of old growth forest in the Pacific Northwest of North America has declined 90% in the last century (Society of American Foresters 1984, Haynes 1986). Fire is big threat to this species’ population. A stand replacing fire could severely degrade and/or diminish its current range.

Polyozellus species are edible, but not highly regarded in North America. They are highly prized dye fungi, and are indiscriminately collected by fibre artists.

This species (as Polyozellus multiplex) was included on the Northwest Forest Plan list of rare and/old growth forests dependent species, and has been actively surveyed for since the late 1990’s (Castellano et al. 1999). Habitat where this species is found to occur should be considered for protection from logging and large scale forest disturbance. Logging and machine clearing of understory vegetation should be limited in mature and old growth forest in areas where this species might occur.

Continued surveys for existing subpopulations are need to better understand population trends and habitat restraints and requirements; i.e. is it restricted to old growth forests?