Assessment Notes

Justification

Cantharellus sphaerosporus is a species of northeastern North America. It is associated with conifers, including Eastern Hemlock, Tsuga canadensis, which is undergoing a relatively rapid decline due to an invasive pest the Hemlock Woolly Adelgid (Adelges tsugae). With a shorter generation length than its hemlock host, and the potential to be associated with other species it is not expected to be declining at a similar rate over three generations (50 years in the case of the fungus), and so wouldn't approach the thresholds for consideration as threatened under criterion A. However, it is suspected to be undergoing a slow decline. With a wide potential range the species is not expected to warrant listing as threatened under any other criteria and so C. sphaerosporus is assessed as Least Concern. However, further research and monitoring is recommended.

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Taxonomic notes

Although the species has very similar characters to Craterellus tubaeformis, it is retained as a distinct taxon (Petersen 1976, Kuo 2015, I. Olariaga Ibarguren in litt. 2022).

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Geographic range

This is a species of northern North America (Kuo 2015). The type was collected from Newfoundland, Canada (Peck 1898) and further collections have been made in eastern Canada and northeastern USA (e.g. Ontario, Michigan, New York and Vermont; Kuo 2015, MyCoPortal 2023). With this range of records, it is presumed to be relatively widespread in northeastern North America.

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Population and Trends

This is a gregarious species, and while current records are scattered (see MyCoPortal 2023), with wide areas of suitable habitat it is presumed to have a wide extent of distribution and consequently a large population size. This species is associated with conifers including the Eastern Hemlock, Tsuga canadensis (Kuo 2015), and T. canadensis in particular is thought to be undergoing a relatively rapid decline as a result of the invasive Hemlock Woolly Adelgid (Adelges tsugae) (Farjon 2013). The rate of decline of T. canadensis is currently placed in the range 20-25% over three generations (150 years for T. canadensis) (Farjon 2013). The three generation decline for the fungus would not be so high as its three generation period is only 50 years (per Dahlberg and Mueller 2011), and T. canadensis may be only one of many potential hosts (see Kuo 2015), but it is precautionarily suspected to be slowly declining.

Population Trend: Decreasing

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Habitat and Ecology

This is a species of coniferous bog land, where it is mycorrhizal with conifers including Eastern Hemlock, Tsuga canadensis (Kuo 2015). The type was collected from the ground (Peck 1898), but it is also noted as fruiting amongst moss, or on heavily decayed wood, covered in moss (Kuo 2015). Fruiting occurs in the summer and fall (Kuo 2015).

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Threats

The Hemlock Woolly Adelgid (Adelges tsugae) is thought to be causing a relatively rapid decline in Eastern Hemlock (Tsuda canadensis), a potential host for Cantharellus sphaerosporus. This is then likely to be causing a subsequent decline in the fungus.

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Conservation Actions

It has been collected from protected areas such as Algonquin Provincial Park and Lake Superior Provincial Park (MyCoPortal 2023). Work to control the invasive pest that is impacting its host would be beneficial for this species.

Further research is required to get a clearer indication of the full distribution of the species, as well as investigating its ecological requirements. This should study its mycorrhizal relationships, and to what extent it is dependent of Tsuga canadensis, and therefore, the potential impact of Hemlock Woolly Adelgid (Adelges tsugae). Monitoring of T. canadensis will also be important.

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Use and Trade

The taste has been described as "not distinctive", but how widely it is consumed is uncertain.

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Source and Citation

Westrip, J.R.S. 2025. Cantharellus sphaerosporus. The IUCN Red List of Threatened Species 2025: e.T269708166A269708168. Accessed on 27 November 2025.

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• Country occurrence