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  • Under Assessment
  • Preliminary Assessed
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Boletus aurantiosplendens T.J. Baroni

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Scientific name
Boletus aurantiosplendens
T.J. Baroni
Common names
IUCN Specialist Group
Mushroom, Bracket and Puffball
Assessment status
IUCN Red List Category
Proposed by
Noah Siegel
Noah Siegel
Anders Dahlberg

Assessment Notes


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

Described in 1998 from Macon County, North Carolina; since 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. It’s 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.

Why suggested for a Global Red List Assessment?

A very conspicuous ectomycorrhizal fungus associated with hardwoods. Obviously rare and known only from 7 locations. The species is described as late as in 1998. The appearance is distinct with it’s bright, striking colours and in this area with a history of frequent monitoring by mycologists specializing on boletes it would have been noticed more frequently if the species was not rare.

Geographic range

Described in 1998 from Macon County, North Carolina; since found from seven locations within 600 km to the south and west of this site. Known from central and western North Carolina, western South Carolina, northern Georgia and eastern Tennessee.

Population and Trends

Currently known from seven locations suggest that this fungus is rare, and relatively range restricted. Because it was described fairly recently, and so few locations are known, it’s not feasible to assess the population trend.

Known 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 to be 70, bases 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.

We have 7 known sites ; x10 =potential total no of sites 70. Using the suggested proxies of 2 genets/site and 10 ramets/genet results in 1400 mature individuals.

Population Trend: Uncertain

Habitat and Ecology

Very little is known about the preference of this species. Mature southern cove hardwood forest, with American Beech, Oak, Hickory, and Tulip Popular. Likely mycorrhizal with hardwoods.



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 decline in this species.

If this species 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) should be considered a serious threat; Gora, et. al. (1996)

Conservation Actions

Research needed

A better understanding of it’s preferred habitat; very little is known about the preferences of this species. Does it need mature or old growth? Early succession? Identify the mycorrhizal host; if it’s associated with beech, beech bark disease is a serious threat.

Use and Trade


Baroni, T.J. 1998. Boletus aurantiosplendens sp. nov.from the southern Appalachian Mountains with notes on Pulveroboletus auriflammeus, Pulveroboletus melleouluteus and Boletus auripes. Bulletin of the Buffalo Society of Natural Sciences. 36:245-255

Bessette AE, Roody WC, Bessette AR. (2000). North American Boletes. Syracuse, New York: Syracuse University Press.

Gora, V., König, J.,Lunderstädt, J 1996. Population dynamics of beech scale (Cryptococcus fagisuga) (Coccina, Pseudococcidae) related to physiological defence reactions of attacked beech trees (Fagus sylvatica). Chemoecology, 7(2):112-120; 30 ref.

Known distribution - countries

Regional Population and Trends

Country Trend Redlisted