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Boletus aurantiosplendens T.J. Baroni

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Scientific name
Boletus aurantiosplendens
Author
T.J. Baroni
Common names
 
IUCN Specialist Group
Mushroom, Bracket and Puffball
Kingdom
Fungi
Phylum
Basidiomycota
Class
Agaricomycetes
Order
Boletales
Family
Boletaceae
Assessment status
Published
Assessment date
2017-03-28
IUCN Red List Category
NT
Assessors
Siegel, N.
Reviewers
Dahlberg, A.

Assessment Notes

The content on this page is fetched from The IUCN Red List of Threatened Species: https://www.iucnredlist.org/species/95383424/95385404

Justification

Boletus aurantiosplendens is an ectomycorrhizal fungus forming very conspicuous yellow sporocarps associated with hardwoods. It is  obviously rare, being known from only seven locations. The combination of the bright, striking colors, distinctive appearance, and not being described until 1998, even though it occurs in an area with a history with mycologist specializing on boletes, makes this a rare species.

The few records does not enable a population trend to be worked out. Therefore, the species is assessed as Near Threatened (NT) based on criterion D1. The assessment is based on the rareness of B. aurantiosplendens: there are limited number of collections of this distinctive and striking mushroom, despite its distribution being within an area that has a long history of mycological collecting. There are seven known sites and the total number of sites is not expected to exceed 70. Using the suggested estimates of two genets per site and ten ramets per genet (Dahlberg and Mueller 2011) results in an estimation that the total population size may not exceed 1,400 mature individuals. 



Taxonomic notes

Boletus aurantiosplendens was described in 1998 from Macon County, North Carolina; it has since been found from seven locations within 600 km to the south and west of this site. It is easily distinguished by the bright golden yellow color of the entire fruitbody, lack of staining reaction, and medium to large size.

Most similar is Boletus auriflammeus, a smaller species with a bright yellow to golden yellow cap and stipe, and typically paler pores. Besides the smaller size, it can be distinguished from B. aurantiosplendens by the whitish flesh, very finely powdery cap and stipe when young, and matted fibrillose cap in age. Boletus auriflammeus is a widespread, but uncommon species in hardwood forest across the southeast and mid Atlantic.

Buchwaldoboletus species have plush, often velvety cap, blue staining pores and often grow on, or near decaying pine stumps. Tylopilus balloui has an orange cap, buff to pinkish buff pores and stipe that darken with age and whitish flesh.

Geographic range

Boletus aurantiosplendens appears to be endemic to the southern part of the Appalacian mountains in eastern US. It was described in 1998 from Macon County, North Carolina, US, and since then only found from seven locations within 600 km to the south and west of this site; located in central and western North Carolina, western South Carolina, northern Georgia and eastern Tennessee.

Population and Trends

Boletus aurantiosplendens is currently (2017) known from seven locations suggesting that this fungus is rare and relatively restricted in range. Because it was described fairly recently (Baroni 1998), and so few locations are known, it is not feasible to assess the population trend.

Known records are from three collections (from two locations) on MycoPortal and four observations (one of which is questionable) on Mushroom Observer (2016), and a single location from a social media posting (2015). We estimate the total number of sites not to exceed 70 (seven known sites x 10 potential), based on the relatively small geographical range, number of mycologist who have collected and worked on boletes in this area, and the relative ease to see and identify this species. Using the suggested proxies of two genets per site and ten ramets per genet results in 1,400 mature individuals (Dahlberg and Mueller 2011).

Population Trend: unknown


Habitat and Ecology

Boletus aurantiosplendens is an ectomycorrhizal fungus probably associated with hardwoods. Very little is known about the habitat and host preferences. It is found in mature southern cove hardwood forest, with American Beech, Oak, Hickory, and Tulip Popular. As for most ectomycorrhizal fungi, the individual mycelia, the unique genotype, is long-lived, many decades or more and can potentially live as long as the there is a continuous presence of its host trees.

Threats

Although there are many small threats to southeastern cove hardwood forest, (localized logging, urban development, increase in nitrogen, moonshine stills) there is no single threat that one can pinpoint for a potential decline in Boletus aurantiosplendens populations.

If B. aurantiosplendens is found to be associated with American Beech (Fagus grandifolia), then the spread of beech bark disease (the combination of a scale insect Cryptococcus fagisuga, and a couple of species of the fungus Nectria) may be a serious threat (Gora et al. 1996).

Conservation Actions

Research is needed on Boletus aurantiosplendens to better understand it’s preferred habitat. Very little is known about the preferences of this species, whether it requires mature or old growth forest, or early succession stages. We also need to identify the mycorrhizal host partner, the required woody plant species. If it is associated with beech then beech bark disease is a serious threat.

Source and Citation

Siegel, N. 2017. Boletus aurantiosplendens. The IUCN Red List of Threatened Species 2017: e.T95383424A95385404. https://dx.doi.org/10.2305/IUCN.UK.2017-3.RLTS.T95383424A95385404.en .Accessed on 31 January 2022

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