Assessment Notes

Justification

As this is a bright orange, highly visible and sought after species, it is probably not common. It is estimated that there are up to 1000 unrecorded sites each with up to 5 collections resulting in an estimate of number of mature individuals of up to 15,000.
While there is no evidence of decline in this species, the continued advance of invasive ectomycorrhizal species such as Amanita muscaria / Chalciporus piperatus may be impacting its population size. Because of uncertainty regarding the population size and the possibility of decline, it is assessed as Data Deficient.

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Taxonomic notes

Chalciporus aurantiacus is an uncommon New Zealand endemic of beech forests (Nothofagaceae). It is similar to the common, introduced Chalciporis piperatus but has more persistent orange/red colours and lacks the yellow mycelium at the stipe base, which is diagnostic of C. piperatus.

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Geographic range

This is a New Zealand endemic species found on both North and South Island. It is mycorrhizal with Nothofagaceae (beech).

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Population and Trends

It is known from 23 records from 13 localities. There are only 5 confirmed sightings since 2013 coinciding with an increase in sightings of the invasive C. piperatus (52 in the same period). 

Over the last five years, 2,500 observers have recorded 54,000 observations of fungi in New Zealand using the iNaturalist platform (2019). 20,000 observations have been verified by multiple experts. However, only four confirmed records of C. aurantiacus have been posted.

As this is a bright orange, highly visible and sought after species, it is probably not common. It is estimated that there are up to 1000 unrecorded sites each with up to 5 collections resulting in an estimate of number of mature individuals of up to 15,000.
While there is no evidence of decline in this species, the continued advance of invasive ectomycorrhizal species such as Amanita muscaria / Chalciporus piperatus may be impacting its population size.

Population Trend: unknown

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Habitat and Ecology

Chalciporus aurantiacus is only known from beech forests (Nothofagacaeae). Its mode of nutrition is unknown. The majority of boletes are ectomycorrhizal but it is likely the Chalicporoidea are parasites of other fungi. The related introduced C. piperatus is thought to be a parasite on the mycelium of the introduced and invasive ectomycorrhizal Amanita muscaria. If C. aurantiacus is a fungal parasite, its host is unknown but will be an indigenous ectomycorrhizal fungus.

A possible explanation for the limited known distribution and small population size of C. aurantiacus is that its host is restricted.

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Threats

The most significant threat to C. aurantiacus is displacement by the exotic C. piperatus and its exotic host species Amanita muscaria. These latter two species have long been present in New Zealand as exotic introductions associated with introduced trees, especially in plantation forestry. From the 1960s Amanita muscaria and Chalciporus piperatus started spreading in native forests, first in South Island and later in North Island. In some areas they are now the dominant ectomycorrhizal species and their range continues to expand. They are now present in all the recorded locations of C. aurantiacus except one and may be reducing the area of possible habitat.

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Conservation Actions

Research is needed on the impact on native populations of ectomycorrhizal fungi as a consequence of invasion by exotic ectomycorrhizal fungi.

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Use and Trade

This species is not utilised.

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Source and Citation

Cooper, J.A. 2019. Chalciporus aurantiacus. The IUCN Red List of Threatened Species 2019: e.T154237654A154237661. https://dx.doi.org/10.2305/IUCN.UK.2019-3.RLTS.T154237654A154237661.en .Accessed on 4 February 2025

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• Country occurrence