• Proposed
  • Under Assessment
  • Preliminary Assessed
  • VUAssessed
  • 5Published

Boletinellus merulioides (Schwein.) Murrill

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Scientific name
Boletinellus merulioides
Author
(Schwein.) Murrill
Common names
 
IUCN Specialist Group
Mushroom, Bracket and Puffball
Kingdom
Fungi
Phylum
Basidiomycota
Class
Agaricomycetes
Order
Boletales
Family
Boletinellaceae
Assessment status
Assessed
Preliminary Category
VU A3e+4ce
Proposed by
Noah Siegel
Assessors
Noah Siegel
Comments etc.
Else Vellinga
Reviewers
Anders Dahlberg

Assessment Status Notes

Is the projected decline for B merulioides ok?

Justification

Boletinellus merulioides is a common, well-known and widespread terrestrial fungus restricted to ash in eastern North America, west into the plains states, and with planted ash in Colorado and Oregon. It has a fascinating symbiosis with the leaf-curl aphid associated with ash. Ash (Fraxinus spp.) is rapidly declining from the invasion of the Emerald Ash Borer, (Agrilus planipennis) from Asia starting in the early 2000’s. The Emerald Ash Borer has rapidly spread across much of the native range of ash, shows no sign of stopping and is devastating for all North American ash species. It cause near 100% mortality in mature ash trees. Since 2017, White Ash (Fraxinus americana) the most common native ash of the USA, is Red-listed as Critically Endangered with an estimated decline of 80% in 100 years. Boletinellus merulioides will decline in concert with the decline of ashes. The decline is estimated to exceed 30% in 30 years (corresponding to 3 generations of B. merulioides). It is listed as Vulnerable.


Taxonomic notes

First described by Schweinitz in 1832 as Daedalea merulioides, based on a collection from Massachusetts, USA, Murrill transferred the species to the genus Boletinellus in 1909. Singer transferred it into Gyrodon (1938). genetic studies showed it wasn’t closely related to Gyrodon, and belonged in the genus Boletinellus.


Why suggested for a Global Red List Assessment?


Geographic range

Common and widespread in eastern North America, west into the plains states, and with planted ash in Colorado and Oregon. Also reported from Mexico and Asia; these collections should be compared with the eastern North American species.


Population and Trends

Common and widespread in eastern North America, west into the plains states, and with planted ash in Colorado and Oregon. Also reported from Mexico and Asia; these collections should be compared with the eastern North American species. Disappearing at a rapid pace with the invasion of the Emerald Ash Borer, (Agrilus planipennis) killing the host trees in large swaths of the current range. Jerome et.al put population decline of at least 80% over the next 100 years for F. americana. Boletinellus merulioides will decline in concert with the decline of ashes. The decline is estimated to exceed 30% in 30 years (corresponding to 3 generations of B merulioides, cf. Dahlberg & Mueller, 2011).

Population Trend: Deteriorating


Habitat and Ecology

This fungus is found growing alone or scattered under ash trees and has a complex symbiotic relationship with the leafcurl ash aphidan (Meliarhizophagus fraxinifolii) occurring on the roots of ash (Fraxinus) species. The fungus forms small sclerotia encapsulating the aphids, getting nutrients from the aphid’s ‘honeydew’ (a mix of sugars, amino acids and minerals)

Temperate Forest

Threats

Ash is rapidly declined in North America from the invasion of the Emerald Ash Borer, (Agrilus planipennis) from Asia starting in the early 2000.The Emerald Ash Borer has rapidly spread across much of the native range of White Ash,shows no sign of stopping and is devastating for all North American ash species. It cause near 100% mortality in mature ash trees. Since 2017, White Ash (Fraxinus americana) the most common native ash of the US red-listed as Critically Endangered with an estimated decline of 80% in 100 years.


Conservation Actions


Research needed


Use and Trade


Bibliography

Brundrett M.C. & B. Kendryck, 1987. The relationship between the ash bolete (Boletinellus merulioides) and an aphid parasitic on ash tree roots. Symbiosis 3: 315–319.

Jerome, D., Westwood, M., Oldfield, S. & Romero-Severson, J. 2017. Fraxinus americana. The IUCN Red List of Threatened Species 2017: e.T61918430A61918432. http://dx.doi.org/10.2305/IUCN.UK.2017-2.RLTS.T61918430A61918432.en.

Murrill WA (1909). “The Boletaceae of North America – 1”. Mycologia. 1 (1): 4–18.

Singer R. (1938). “Sur les genres Ixocomus, Boletinus, Phylloporus, Gyrodon et Gomphidius. 2. Les Boletinus”. Revue de Mycologie (in French). 3 (4–5): 157–77.


Known distribution - countries

Regional Population and Trends

Country Trend Redlisted