Leucocortinarius bulbiger (Alb. & Schwein.) Singer

Phylum: Basidiomycota - Class: Agaricomycetes - Order: Agaricales - Family: Tricholomataceae

Leucocortinarius bulbiger, Wales UK

Despite the term 'cortinarius' appearing in its scientific name, this rare mushroom is not closely related to the webcaps (Cortinarius species); its spore print is pure white, which places it in the family Tricholomataceae. In fact apart from the Hebeloma-like cap and the Cortinarius-like bulbous stem base, everything about this mushroom suggests that it is a relative of those Tricholoma species that produce chunky fruitbodies with membranous stem rings - as for example does Tricholoma focale.

Leucocortinarius bulbiger, Wales UK

Distribution

It is always difficult to provide meaningful distribution information for fungi with very few recent records, and in Britain and Ireland there are virtually no authenticated records in recent years for Leucocortinarius bulbiger.

It was during a British Mycological Society foray in eastern Wales that Richard Shotbolt and I came across a group of fruitbodies which, to my amazement, Richard immediately identified as Leucocortinarius bulbiger - even before seeing the bulous stem base. A white spore print supported this suggestion, but only after examining the spores and basidia and finding an absence of cheilocystidia was it confirmed, with Geoffrey Kibby's endorsement, that this was indeed the rare and very elusive Leucocortinarius bulbiger. A voucher specimen was dried and sent off to the mycology department at Kew.

Taxonomic history

When in 1805 German-born mycologists Johannes Baptista von Albertini (1769 - 1831) and Lewis David von Schweinitz (1780 -1834) described this chunky mushroom they gave it the scientific name Agaricus bulbiger. In 1945 Rolf Singer transferred this species to the new genus Leucocortinarius, whereupon its name became Leucocortinarius bulbiger.

Synonyms of Leucocortinarius bulbiger include Agaricus bulbiger Alb. & Schwein., Armillaria bulbigera (Alb. & Schwein.) P. Kumm., and Cortinarius bulbiger (Alb. & Schwein.) J.E. Lange.

Etymology

The generic name comes from Leuco- meaning white, and -cortinarius which is a genus of fungi with rusty-brown spores. In this monotypic genus the species of interest looks rather like a bulbous-based Cortinarius mushroom but with white spores and a membranous partial veil. (Most Cortinarius species have web-like partial veils or cortinas - hence their common name webcaps.)

The specific epithet bulbiger is a reference to the swollen bulbous base of the stem.

Identification guide

Cap of Leucocortinarius bulbiger, Wales UK

Cap

Orange-brown to reddish-brown, cracking as it ages; convex, developing a flat top, margin inrolled; 7 to 12cm across.

Gills of Leucocortinarius bulbiger, Wales UK

Gills

White, becoming creamwith age; adnexed to free; moderately crowded, adnate-emarginate.

 

Stem base of Leucocortinarius bulbiger

Stem

White and fibrous above a fragile superior (pendent) ring, tapering towards the apex; 4 to 8cm long, 2 to 4cm diameter.

The stem base (left) is swollen and in most instances quite abruptly bulbous.

Spores of Leucocortinarius bulbiger

Spores

Ellipsoidal, smooth, 7-8 x 4-5µm, with a hilar appendage; inamyloid.

Show larger image

Spore print

Pale creamy white.

Odour/taste

Taste mild but not significant. Some reports refer to a cherry-like odour, but I couldn't detect it.

Habitat & Ecological role

Mostly reported from under conifers, but also found in acid grassland.

Season

Late summer and autumn.

Similar species

This mushroom bears a superficial resemblance to some bulbous-based webcaps (Cortinarius species) but its spore print is pure white rather than rusty brown.

Culinary Notes

Because of the rarity of this mushroom, it should be treated as just for looking, not for cooking.

Reference Sources

BMS List of English Names for Fungi

Dictionary of the Fungi; Paul M. Kirk, Paul F. Cannon, David W. Minter and J. A. Stalpers; CABI, 2008

Taxonomic history and synonym information on these pages is drawn from many sources but in particular from the British Mycological Society's GB Checklist of Fungi and (for basidiomycetes) on Kew's Checklist of the British & Irish Basidiomycota.

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