Assessment Notes

Justification

Stereopsis humphreyi is a peculiar saprotrophic very rare fungal species, occurring in coastal old-growth conifer forests from Southeast Alaska southwards to central Oregon. The known sites are scattered along the coast from central Oregon northwards to Sitka in Alaska. The species is conspicuous, but has only been reported from 25 locations and from a narrow strip bordering the ocean. Its habitat, wet mucky places near creeks and ponds of coastal old-growth forests, is declining due ongoing to clear cutting. It is assessed as Near Threatened based on having a small, largely unrecorded population along the coast with a total of fewer than 300 localities and an estimated number of less than 15000 mature individuals, with under 50 in the largest subpopulation, with a continuing decline in population size due to habitat decline arising from ongoing forest management.

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Taxonomic notes

Stereopsis humphreyi is a member of the Agaricales, whereas the type species of the genus is unrelated, and placed (with other species in Stereopsis) in its own order, Stereopsidales (Sjøkvist et al. 2012; 2014), close to the Phallomycetidae. This implies that Stereopsis humphreyi has to be moved into its own genus.

Stereopsis humphreyi takes an isolated position within the Agaricales, and is surrounded by gilled mushrooms (Moncalvo et al. 2002). It does not have close relatives that share the simple, non-gilled hymenophore. The records of Stereopsis humphreyi from interior China are not considered to belong to the same species as the western American species.

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Geographic range

Stereopsis humphreyi is distributed from central coastal Oregon in the U.S.A. northwards via Haida Gwaii [formerly known as Queen Charlotte Islands] in Canada to southeast Alaska. All localities are at sea level and coastal.

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Population and Trends

The species is known to occur or to have occurred in around 25 localities that are scattered along the coast from central Oregon to Southeast Alaska. The species has repeatedly been found over the span of 70 years on some of these locations (e.g. at the type locality). In the southern part of its area, available habitat is spotty and does not form a continuous belt. Habitat on Haida Gwaii (in the northern part of its occurrence) is available and forms a more continuous zone along the coast. Data on occurrence on the coast of mainland British Columbia are not available. The extent of occurrence is over 20,000 sq km.

The number of localities is estimated not to exceed 300 considering unrecorded localities along the coast. There are typically only a few fungal mycelia of S. humphreyi at each location, hence the estimated total number of mature individuals is estimated to not exceed 15,000 (c.f. Dahlberg and Mueller 2011). Its habitat of coastal old-growth forests has declined significantly and is experiencing ongoing decline due to clear cutting.

Population Trend: decreasing

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Habitat and Ecology

Stereopsis humphreyi is presumed to be a saprotrophic fungus growing on needle debris in coastal lowland old-growth coniferous forests with Sitka Spruce (Picea sitchensis), Western Red Cedar (Thuja plicata) and Western Hemlock (Tsuga heterophylla), in wet, muddy, mossy places (Redhead and Reid 1984, Kroeger et al. 2012, Siegel pers. comm). It stands out in the dark forest because of its white fruitbodies that resemble angel wings on a stem. Like other litter- and ectomycorrhizal fungi, individual mycelia are perennial and persist for many years (Dahlberg and Mueller 2011).

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Threats

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), and coastal forest in particular has been heavily logged. Lumber operations in British Columbia started in the 1850s, whilst those in the USA started in the late 1800s, but clear cutting started in earnest early in the 20th century, and has been ongoing since. The existing sites where this species occurs are scattered, some are in protected areas such as National Parks in the U.S.A. or National Park Reserve or Provincial parks in Canada.

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Conservation Actions

Protection of known sites is the key conservation action required for this species. Research is also needed: The taxonomy of this species has to be settled, and the identity of the Chinese collections to be established. The nutritional mode is not known, but judging from the phylogenetic position, it is expected to be saprotrophic (see Moncalvo et al. 2002).

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Use and Trade

The species is not known to be used.

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Source and Citation

Vellinga, E.C. 2019. Stereopsis humphreyi. The IUCN Red List of Threatened Species 2019: e.T125433334A125435435. https://dx.doi.org/10.2305/IUCN.UK.2019-3.RLTS.T125433334A125435435.en .Accessed on 6 February 2024

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• Country occurrence