Byssomerulius corium (Pers.) Parmasto - Netted Crust

Phylum: Basidiomycota - Class: Agaricomycetes - Order: Polyporales - Family: Phanerochaetaceae

Byssomerulius corium, Netted Crust

This corticioid (crust-like) fungus is a real beauty, especially when young and fresh and seen in its bracket form backlit by sunlight.


Byssomerulius corium is fairly common find in Britain and Ireland. This corticioid (crust) fungus has also been recorded throughout mainland Europe as well in Asia, Africa, the Americas and Australia.

Byssomerulius corium, Netted Crust, closeup of fertile surface

Taxonomic history

Netted Crust fungus was described in 1783 by French naturalist Jean Baptiste Francois (Pierre) Bulliard, who gave it the name Auricularia papyrina. The basionym (first valid name) dates from the 1801 publication of Christiaan Hendrik Persoon's Synopsis Methodicae Fungorum (and subsequently sanctioned in 1828 by Elias Magnus Fries) in which Netted Crust is given the name Thelephora corium (effectively - Classifying it with the various earthfan fungi).

The currently-accepted scientific name Byssomerulius corium dates from a 1967 publication by the Estonian mycologist Erast Parmasto (1928-2012), who designated Byssomerulius corium as the type species of its genus.

Synonyms of Byssomerulius corium include Auricularia papyrina Bull., Thelephora corium Pers., Boletus purpurascens DC.Merulius confluens Schwein., Merulius corium (Pers.) Fr.Merulius aurantiacus Klotzsch, and Merulius papyrinus (Bull.) Quél.

Byssomerulius corium, Netted Crust, infertile surface


Byssomerulius, the genus name, comes via Greek from the Latin byssus, meaning fine silk-like cloth and is probably a reference to the many fine maze-like ridges that pattern the surface of these fungi rather like interlocking jigsaw pieces, and -merulius is the name (origin obscure) of the closely-related Merulius crust fungus genus. The specific epithet corium means a skin or hide, as in leather, and is a reference to the resupinate skin-like form that the fruitbodies of this species take (at least when initially forming and in many instances throughout the life of the fruitbodies).

Identification guide

Closeup of Cobalt Crust Teranea caerulea


Irregular but mostly resupinate, sometimes forming brackets. Fruitbodies coalesce to form large patches or tiered brackets with lower (fertile) whitish surface covered in snaking net-like ridges or elongated warts. The pale upper surface, where visible, is faintly zoned and fibrous or finely downy, becoming finely hairy at the margin.

The white flesh is tough and leathery.



Elongated ellipsoidal to cylindrical, smooth, 4.5-7.5 x 2.3-3μm; hyaline or very nearly so; inamyloid.

Spore print



No noticeable odour; very tough when dry, waxy when wet, but tasteless.

Habitat & Ecological role

Saprobic, on fallen hardwood trees, branches and twigs, mostly on the undersides; commonly on Ash, causing white rot.


Seen throughout the year, but shedding spores mainly in autumn.

Similar species

Stereum subtomentosum is sometimes entirely resupinate and then similar in form to Netted Crust, but it is usually various shades of greyish-orange.

Culinary Notes

These tough and tasteless fungi are inedible and of no culinary value.

Reference Sources

Ellis, J. B.; Ellis, Martin B. (1990). Fungi Without Gills (Hymenomycetes and Gasteromycetes): an Identification Handbook. London: Chapman and Hall. (Cobal Crust included as Pulcherricium caeruleum)

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

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.


This page includes pictures kindly contributed by Simon Harding.

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