Neoboletus luridiformis (Rostk.) Gelardi, Simonini & Vizzini - Scarletina Bolete

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

Neoboletus luridiformis - Scarletina Bolete, picture copyright David Kelly

Neoboletus luridiformis is reported to be edible, but this bolete is could easily be confused with poisonous species such as Suillelus satanas, the Lurid Bolete.

Distribution

Fairly common in deciduous woodland and pine forests in Britain and Ireland, this attractive red-stemmed bolete is often found among bilberries. This bolete occurs also in many parts of North America, where it associates mainly with spruce.

When damaged the flesh of this chunky-stemmed mushroom turns blue very quickly, as can be seen in the Flash movie shown below:

Neoboletus luridiformis var. discolor

Taxonomic history

Neoboletus luridiformis was described in 1796 by Christiaan Hendrik Persoon, who gave it the name Boletus erythropus; however, the basionym dates from an 1844 publication by German mycologist Friedrich Wilhelm Gottlieb Theophil Rostkovius (1770 - 1848), who gave it the scientific name Boletus luridiformis.

Synonyms of Neoboletus luridiformis include Boletus luridiformis (Rostk.) and Boletus discolor (Quél.) Boud.

The autonomous form, var. luridiformis, has a darkish cap and a densely dotted ruddy stem. Another similar bolete previously known as Boletus luriformis var. discolor (Quel.) Krieglst., was described in 1991 by Lothar Gundolf Krieglsteiner (born 1965); it has a paler cap and a less ruddy yellowish stem that is only very lightly patterned with very fine red dots. This latter mushroom is mycorrhizal with oaks, and many authoroties now consider it to be just a colour form of Neoboletus luridiformis. (An example is shown above.)

Etymology

The generic name Boletus comes ​​from the Greek bolos, meaning 'lump of clay', while the prefix neo- means new or young, and in taxonomy it is used to indicate a recent cladistic branch.

The specific epithet luridiformis suggests that this species is similar in form to Suillelus luridus.

Identification guide

A large Scarletina Bolete, Neoboletus luridiformis

Cap

The cap colour of this often massive bolete is very variable. It can be dark chocolate brown, pale brown or even, as in this fine specimen, coppery bronze. The cap flesh is yellow, rapidly bluing when cut or bruised.

Caps of Neoboletus luridiformis are initially downy and convex, becoming flatter, smooth and shiny as the fruitbody matures. The diameter at maturity varies between 8 and 20cm.

 

Pores of Neoboletus luridiformis

Tubes and Pores

Orange at first, the round, crowded pores soon become bright red and then rusty brown with age.

The spore tubes are lemon yellow, but they very quickly turn blue-green when cut or bruised.

Stem of Neoboletus luridiformis

Stem

Apart from a pale area near the apex, a pattern of tiny red dots covers most of the stem of Neoboletus luridiformis. (A hand lens may be necessary to distinguish the separate dots on some specimens.)

Typically 2 to 4cm in diameter and more or less parallel sided, stems of the Scarletina Bolete range between 7 and 15cm tall and have yellow flesh that instantly turns blue-green when cut or bruised.

Spores of Neoboletus luridiformis

Spores

Sub-fusiform (broadly spindle-shaped) to broadly ellipsoidal, 12-16 x 4.5-6µm.

Show larger image

Spore print

Olive-brown.

Odour/taste

Not distinctive.

Habitat & Ecological role

On acid soils under conifers, particularly spruces, and under beeches; and (var. discolor) occasionally oaks, most often at the edge of a wood or a clearing. The Scarletina Bolete is known to form ectomycorrhizal associations with both spruce (Picea spp.) and beech (Fagus spp.) and (for var. discolor) with oaks.

Season

August to October in Britain and Ireland.

Similar species

Suillelus luridus is similar but has a red net pattern on its stem.

Suillelus satanas has a chalky white cap and a bulbous stem covered in a bright red net pattern on a yellow background; it is poisonous.

Neoboletus luridiformis, Scarletina Bolete, picture by Dave Kelly

Culinary Notes

Neoboletus luridiformis, the Scarletina Bolete, is reported to be edible, but this mushroom is easily confused with poisonous species such as Suillelus satanas, the Devil's Bolete. (These are mushrooms that turn black when they are cooked, and the appearance of such a meal may be off putting to some people.)

Reference Sources

Fascinated by Fungi, Pat O'Reilly 2016.

BMS English Names for Fungi

Roy Watling & Hills, A.E. 2005. Boletes and their allies (revised and enlarged edition), - in: Henderson, D.M., Orton, P.D. & Watling, R. [eds]. British Fungus Flora. Agarics and boleti. Vol. 1. Royal Botanic Garden, Edinburgh.

Neoboletus luridiformis - Scarletina Bolete

British Boletes, with keys to species, Geoffrey Kibby (self published) 3rd Edition 2012

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.

Watling, R. 2004. New combinations in Boletaceae and Gomphidiaceae (Boletales). – Edinburgh Journal of Botany 61: 41–47.

Knudsen, H. & Vesterholt, J. [eds.]. 2008. Funga Nordica. Nordsvamp, Kopenhagen.

BMS English Names for Fungi

Other web pages about this species

Boris Assyov (Bulgaria)

Leif Goodwin (UK)

Acknowledgements

This page includes pictures kindly contributed by David Kelly.

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