Chroogomphus rutilus (Schaeff.) O.K. Mill. - Copper Spike

Phylum: Basidiomycota - Class: Agaricomycetes - Order: Boletales - Family: Gomphidiaceae

Chroogomphus rutilus - Copper Spike

Chroogomphus rutilus is found beneath pine trees, with which it forms ectomycorrhizas. The copper-brown cap of this attractive fungus is slimy when wet and dries to a bright glossy copper sheen.

Distribution

Fairly frequent in Britain and Ireland, Chroogomphus rutilus is found throughout Europe and was until recently thought to occur also in the USA; that has been shown to be a different species, now called Chroogomphus ochraceus. Growing under pines, the pair of Copper Spike fungi pictured above were seen in western Ireland.

Chroogomphus rutilus, France

Taxonomic history

First described scientifically in 1774 by Jacob Christian Schaeffer, who gave it the binomial scientific name Agaricus rutilus (at a time when most gilled fungi were initially placed in the genus Agaricus - since redistributed), this species was transferred to the genus Chroogomphus in 1964 by American mycologist Orson K. Miller, Jr., (1930 - 2006).

Synonyms of Chroogomphus rutilus are many and varied. They include Agaricus rutilus Schaeff., Agaricus gomphus Pers., Cortinarius rutilus (Schaeff.) Gray, Gomphidius rutilus (Schaeff.) S. Lundell & Nannf., Gomphidius viscidus f. giganteus J. E. Lange, Chroogomphus rutilus var. rutilus (Schaeff. O.K. Mill., Chroogomphus corallinus O.K. Mill. & Watling, Chroogomphus britannicus A.Z.M. Khan & Hora, and Chroogomphus rutilus var. corallinus (O.K. Mill. & Watling) Watling.

Chroogomphus rutilus is the type species of the genus Chroogomphus and the only member of that genus known to occur in Britain and Ireland. Other so-called Spikes are found in Britain, but they belong to the related genus Gomphidius - Gomphidius roseus and Gomphidius glutinosus are two such examples. Although they have gills rather than pores, fungi in the family Gomphidiaceae are more closely related to the boletes than to the agaricales - inkcaps, webcaps, waxcaps, true mushrooms (Agaricus species) etc. Within the Boletales, the 'spikes' are more closely related to Suillus than to Boletus, which may partly explain their mycorrhizal preference for pine trees.

Etymology

Chroogomphus comes from the Greek 'gomphos', a large conical (wedge-like) nail or bolt with a large head, made of either metal or wood and used mainly in ship-building. The prefix "chroo-" means colour(ed). The conical shape of the fruitbodies means that they look very much like those ancient bolts.

The specific epithet rutilus means shining red or golden - quite appropriate for these brilliantly polished caps.

Identification guide

Cap of Chroogomphus rutilus, Copper Spike

Cap

5 to 12cm in diameter (exceptionally 15cm) the coppery caps of Chroogomphus rutilus take on a metallic sheen on sunny days. Occasional specimens flatten fully, sometimes with a sharp umbo, but more often the caps remain convex when mature. The pale cap flesh is vinaceous (tinted like red wine). In wet weather the caps of this species are viscid, drying with a smooth shiny surface.

Gills of Chroogomphus rutilus, the Copper Spike

Gills

Although from its spore characteristics this species is seen to be more closely related to the boletes than to the agaric fungi, it produces its spores via gills rather than pores.

The close, thick gills are initially grey-white or dull olive-buff, but they soon take on a dirty purple hue. They are deeply decurrent.

Stem of Chroogomphus rutilus, Copper Spike

Stem

5 to 12mm in diameter and usually 6 to 12cm tall, the stems are reddish or vinaceous towards the top and yellow towards the base. There is a ring at the apex, where the stem narrows abruptly to the region where the gills are attached.

Inside, the stem flesh is firm and solid; like the cap flesh, its colour is vinaceous or pale reddish-brown except near the base, where it becomes chrome yellow.

Spores of Chroogomphus rutilus, Copper Spike mushroom

Spores

The large bolete-like spores are subfusiform, 15-22 x 5.5-7µm.

Show larger image

Spore print

Very dark smoky-olive to black.

Odour/taste

Not distinctive.

Habitat & Ecological role

Ectomycorrhizal, in grass beneath pines and, much less frequently, spruce.

Season

August to November in Britain and Ireland; later in southern Europe.

Similar species

Chroogomphus fulmineus is a southern European species with bright orange tones, a very fibrous stem surface, and a cap that rarely has a central pip.

Gomphidius glutinosus is a much rarer find and occurs under spruce trees; its cap is grey-violet and its stem is white near the cap and lemon grey towards the base. A glutinous zone at the apex of the stem gradually blackens with age.

Culinary Notes

This largish fleshy mushroom is generally reported to be edible, but it lacks flavour and is not highly regarded. We know of no recipes devised for this particular species, and its relative scarcity in most areas is further justification for not treating the Copper Spike mushroom as one for the pot.

Chroogomphus rutilus, central Scotland

Reference Sources

Fascinated by Fungi, Pat O'Reilly 2016.

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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