Delicatula integrella (Pers.) Fayod

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

Delicatula integrella

Looking rather like a tiny Mycena bonnet mushroom, but with gills very widely spaced and often not extending to the rim of the cap, this distinctive little wood-rotting mushroom is beautifully translucent.

Look out for these pretty little fungi on decaying hardwood (they seem to favour Alders particularly) in damp mossy woodlands. These mushrooms can also grow attached to the stems of decaying plants in bogs and marshes.

Delicatula integrella side view

Distribution

In Britain and Ireland Delicatula integrella is an uncommon but far from rare find. This species occurs also in most of mainland Europe.

No doubt this little mushroom would feature more often in foray records were it not so easily overlooked because of its diminutive stature.

Taxonomic history

In the year 1800, famous South-African-bon mycologist Christiaan Hendrik Persoon described this mushroom under the name Agaricus integrellus. (In those early days of fungal taxonomy most gilled fungi were initially placed in a huge Agaricus genus, now redistributed across many other genera.) Swiss mycologist Victor Fayod established the currently-accepted scientific name of this mushroom as Delicatula integrella in an 1889 publication.

Synonyms of Delicatula integrella include Agaricus integrellus Pers., Mycena integrella (Pers.) Gray, Omphalia integrella (Pers.) P. Kumm., Omphalia cuspidata Quél., Delicatula bagnolensis E.-J. Gilbert, and Delicatula cuspidata (Quél.) Cejp.

Delicatula integrella is the type species of the Delicatula. genus, which was erected by Swiss mycologist Victor Fayod in 1899.

Etymology

Delicatula, the genus name, declares the delicate structure of the tiny mushrooms in this taxonomic group, which in Europe is monotypic (containing only one species, Delicatula integrella). The specific epithet integrella comes from the Latin integra, meaning entire; the ending -ella signifies that the thing being described is very small.

Identification guide

Cap and stem of Delicatula integrella

Cap

Pure white when young, becoming yellowish when old; 0.3 to 1cm across; initially ovoid, becoming bell shaped with a flat or depressed central region; smooth but with fine veil fragments when young; translucent and striate except for a central opaque 'eye'; the cap flesh is very delicate.

Gills of Delicatula integrella

Gills

Pure white; vein-like, adnate or slightly decurrent, very widely spaced, irregularly wavy, often forked and with small cross-veins; usually terminating before reaching the cap rim.

Stem

White, smooth, translucent to opaque; cylindrical with a bulbous base, 0.5 to 2.5cm long and 0.5 to 1.5mm in diameter; no stem ring.

 

Spores

Ellipsoidal, ovoid, citriform or amygdaliform; smooth, 7.5-8.5 x 4-5µm; amyloid.

Spore print

White.

Odour/taste

Not distinctive.

Habitat & Ecological role

Saprobic; occurring as singletons or small groups on well-rotted wood or on soil rich in dead leaves and rotten wood fragments, mostly in damp mossy places.

Season

Mostly between mid August and late December in Britain and Ireland.

Similar species

Mycena epipterygia, commonly known as the Yellowleg Bonnet, is also very small and pale and can occur in similar habitats. As the name suggests there is a yellowish tinge to its slightly translucent stem.

Delicatula integrella, seen from underneath the cap

Culinary notes

These fungi are far too small and insubstantial to be of culinary interest. It is unclear whether they are toxic or not.

Reference Sources

Funga Nordica, Henning Knudsen and Jan Vesterholt, 2008.

Fungi of Switzerland, Vol. 3; J. Breitenbach & F. Kranzlin; Mad River Pr (1 Jun 1991).

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.

Acknowledgement

This page includes pictures kindly contributed by David Kelly and Chris Piccini.

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