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Amanita westii (Murrill) Murrill

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Scientific name
Amanita westii
(Murrill) Murrill
Common names
IUCN Specialist Group
Mushroom, Bracket and Puffball
Assessment status
Assessment date
IUCN Red List Category
Lewis, D.P.
Dahlberg, A.

Assessment Notes

The content on this page is fetched from The IUCN Red List of Threatened Species: https://www.iucnredlist.org/species/95383225/95385374


Amanita westii is a rare ectomycorrhizal fungus with conspicuous and large sporocarps that appears to be endemic to the United States Gulf Coast. It is only recorded from seven sites in Florida, Mississippi and Texas after 80 years of collecting by mycologists and mushroom clubs.

The estimated total number of subpopulations is estimated not to exceed 75 with the number of mature individuals estimated to be less than 1500. The habitat of A. westii is not considered to be in decline. Hence, A. westii is assessed to meet the category Near Threatened (NT) under the criteria D1 based on small number of estimated mature individuals.

Taxonomic notes

Described by W. A. Murrill as Venenarius westii then transferred to Amanita in the same paper. Amanita westii, in section Lepidella, is characterized by a medium-sized fruiting body that bruises reddish and has chocolate-coloured gills. It is an easily identified species due to its reddish stains and medium size. It may be confused with Amanita rubescens, however that species has whitish gills (Murill 1945). Tulloss and Lewis (1994) have published a modern description with detailed microscopic data.

Geographic range

Amanita westii is endemic to the Gulf Coast of the United States. The holotype was collected near Newman’s Lake near Gainesville (Alachua Co.), Florida. A second Florida site is known from Apalachicola National Forest (Wakulla Co.) south of Tallahassee. It has been reported from southern Mississippi (Jackson Co. and Perry Co.) and East Texas (Newton and Hardin Co.).

Population and Trends

Murrill described Amanita westii in 1945 from a 1938 specimen found in Florida and did not report any other collections (1935 to 1955). The species was not seen again until found by Lewis in East Texas in 1987. The Gulf States Mycological Society annual summer and winter forays (1979 to 2015) found two single specimens in Mississippi (Jackson Co. 1981 and Perry Co.1991), and a single fruiting body in Florida (Wakulla Co. 1994). The largest specimen, composed of five fruiting bodies, was found by Buyck in Texas in 2007. The most recent specimen, a single fruiting body, was made by Lewis in Big Thicket National Preserve, Texas, in 2008. 
Other mycologists active along the Gulf Coast did not find or report the species: Singer for Florida (1942 to 1945); Thiers for Alabama, Florida, Mississippi and Texas (1950 to 1963); Cibula for Mississippi (1975-2005); Alan and Arleen Bessette for Florida and southern Georgia (2000 - 2105). Although most fungi are overlooked, it is obviously a very rare fungus.

Population Trend: unknown

Habitat and Ecology

Amanita westii is a mycorrhizal fungus species reported under Quercus in a dry hammock (Alachua Co., Murrill 1945) and in a mixed pine and hardwood forest (Wakulla Co.) in Florida. In Mississippi it is found in a mesic forest of Pinus, Quercus and Fagus. In Texas it is associated with a variety of habitats including: Quercus and Carya; with Quercus stellata in a xeric sandy land; and a slope forest with Fagus grandifolia and Quercus alba. The species fruits in summer months from June to September.


The habitat of A. westii is not considered to decline. However, severe drought and hurricane damage may impact populations due to tree mortality and forest destruction. The influx of invasive species such as Chinese Tallow (Sapium sebiferum) and Chinese Privet (Ligustrum sinense) has influenced the overall ecology of the region by replacing native hardwoods. Another problem is the destruction of plants and soil by feral hogs. In Florida, urban sprawl may influence their population. Some sites may be converted to pine plantations.

Conservation Actions

In Florida, the Newman’s Lake population status is unknown; the other Florida site south of Tallahassee is in Apalachicola National Forest. The Mississippi site is within DeSoto National Forest. The first Texas site (1987) is located on a private preserve whose ownership has changed and its fate unknown. The large collection of five fruiting bodies is located in a cemetery site and should remain unaltered. The last collection is within Big Thicket National Preserve, a federal preserve under the National Park Service.
In the Gulf Coast of North America, where A. westii is found, there are numerous groups of amateur mycologists. Members of these groups can be recruited and instructed where to find and how to identify A. westii so they can target this species during forays. Data from amateur mycologists can be critical to define A. westii population size, distribution and trends, as well as its ectomycorrhizal associations. Annual forays by the Gulf States Mycological Society continue to search for other populations. Lewis continues to monitor one Newton Co. site and areas within Big Thicket National Preserve.

Source and Citation

Lewis, D.P. 2019. Amanita westii. The IUCN Red List of Threatened Species 2019: e.T95383225A95385374. https://dx.doi.org/10.2305/IUCN.UK.2019-1.RLTS.T95383225A95385374.en .Downloaded on 31 January 2021

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