Imperator torosus

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Imperator torosus
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Fungi
Division: Basidiomycota
Class: Agaricomycetes
Order: Boletales
Family: Boletaceae
Genus: Imperator
Species:
I. torosus
Binomial name
Imperator torosus
(Fr.) Assyov, Bellanger, Bertéa, Courtec., Koller, Loizides, G.Marques, J.A.Muñoz, N.Oppicelli, D.Puddu, F.Rich. & P.-A.Moreau (2015)
Synonyms[1][2]
  • Boletus torosus Fr. (1835)
  • Dictyopus torosus (Fr.) Quél. (1886)
  • Boletus purpureus var. xanthocyaneus
    Romagn.
    (1948)
  • Boletus xanthocyaneus (Ramain) Romagn. (1976)
Imperator torosus
View the Mycomorphbox template that generates the following list
Pores on hymenium
Cap is convex or flat
mycorrhizal
Edibility is poisonous

Imperator torosus, commonly known as the brawny bolete, is a species of

deciduous trees such as hornbeam, oak and beech in warm, dry locales. Although generally rare in Europe, it appears to be relatively common in Hungary. Appearing in summer and autumn on chalky soils, the stocky fruit bodies have an ochre cap up to 20 cm (8 in) across, yellow pores on the cap underside, and a wine-red to brown or blackish stipe up to 6–15 cm (2.4–5.9 in) long by 3–6 cm (1.2–2.4 in) wide. The pale yellow flesh
changes to different colours when broken or bruised depending on age; younger mushrooms become reddish, and older ones additionally take on bluish tones.

Elias Magnus Fries and Christopher Theodor Hök first described this species as Boletus torosus in 1835, a name by which it came to be known for many years. Modern molecular phylogenetics shows that it is only distantly related to Boletus edulis—the type species of Boletus—and it was duly placed in the new genus Imperator in 2015. Eating raw mushrooms of this species leads to vomiting and diarrhea. Gastrointestinal symptoms have also occurred after eating cooked specimens, though this does not always happen.

Taxonomy

Swiss mycologist

species concept, dividing many taxa into multiple species that were not supported by other authorities, and his works did not use binomial nomenclature consistently.[4][5] Swedish mycologists Elias Magnus Fries and Christopher Theodor Hök described Boletus torosus in 1835 based on Secretan's B. pachypus—distinct from the B. pachypus described by Fries himself.[6][a] Fries reported in his 1838 book Epicrisis Systematis Mycologici seu Synopsis Hymenomycetum that he had not actually observed the species,[7] and he did not designate a type specimen or illustration.[b][8] The specific epithet torosus, which derives from Latin, means "muscular".[9] In the United Kingdom, it is known commonly as the "brawny bolete".[10] The German name Ochsen-Röhrling means "oxen bolete"[11] and the French bolet vigoureux is "strong bolete".[12]

French naturalist

neotype specimen from this region.[8]

Within the large genus Boletus, the brawny bolete was

classified in the section Luridi,[18] which included species producing medium to large fruit bodies with thick, swollen stipes, and minute pores.[19] In 1996, Czech mycologist Jiří Hlaváček further subdivided the section Luridi, defining and naming the subsection Torosi—for B. torosus—to contain boletes that strongly bruised blue-black with handling.[20]

In a

phylogeny, the brawny bolete was most closely related to Boletus luteocupreus; these two species formed a clade that was sister to B. luridus.[21] Genetic analysis published in 2013 showed that B. torosus and many (but not all) red-pored boletes were part of a dupainii clade (named for B. dupainii), well-removed from the core group of Boletus edulis (the type species of genus Boletus) and relatives within the Boletineae. This indicated that the brawny bolete and its relatives needed to be placed in a new genus.[22] It was made the type species of the new genus Imperator,[c] becoming Imperator torosus, in 2015.[23]

Description

The base of the thick stipe is wine-red coloured.

Quite heavy compared with other mushrooms of similar size, the stocky

cap cuticle is bruised, or even touched, there are sudden changes in the colour that depend on the age of the mushroom: young, yellow caps become cherry-red, while ochre-brown cap tissue bruises to reddish-purple. These colour changes soon give way to bluish or greyish tones, which, when combined, give the cap a variegated appearance.[1]

The pores on the cap underside are round and small,[25] the sulfur-yellow colour of the pore surface becoming less intense with age. The squat stipe measures 6–15 cm (2.4–5.9 in) long by 3–6 cm (1.2–2.4 in) thick. Egg-shaped when young, it lengthens somewhat as the mushroom grows, but is still bulbous in maturity; a mature stipe is typically a little shorter than the diameter of the cap. It is initially roughly the same colour as the cap, but as it matures, develops a wine-red colouration near the base and a dirty brown to bluish-black colouration elsewhere. The surface has a mesh-like pattern (reticulation) that has a colour development similar to that of the cap: initially yellow, then purplish, and finally dark brown. The flesh is thick and hard. It is yellow, except for the stipe base where it is deep red or dark brownish in older mushrooms. The pores, stipe and flesh turn greenish-blue with bruising or cutting.[1] The smell is unpleasant, but the taste is mild.[25]

The

hyphae emerge roughly parallel, like hairs, perpendicular to the cap surface. These cylindrical, interwoven hyphae contain septa.[25]

Similar species

The Mediterranean species Boletus poikilochromus somewhat resembles I. torosus, but can usually be distinguished by a smaller fruit body, a cylindrical stipe, and the lighter colours of younger mushrooms. Also, B. poikilochromus does not feature the colour change of the stipe base in mature fruit bodies that is seen in I. torosus.[26] Imperator luteocupreus and Caloboletus radicans are also similar but the pores of the former are red, and the flesh of the latter has a bitter taste.[25]

Several

formalin–mid blue (slow).[16]

Toxicity

Like many boletes, Imperator torosus causes gastrointestinal symptoms such as abdominal pain, diarrhoea, and vomiting when eaten raw. These reactions can also happen to some people when the mushroom is eaten cooked, though others have consumed it with no ill effects.[24] In a 1994 study, researchers Ulrich Kiwitt and Hartmut Laatsch looked for the antabuse-like compound coprine in Suillellus luridus and similar species that had been suspected of inducing Antabuse-like reactions with alcohol.[27] Coprine ingestion results in heat and flushing in the face, tingling in arms and legs, nausea and vomiting, and increased heart rate within five to ten minutes of consuming alcohol.[28] They found none in the suspect species, but did find indications for it in Imperator torosus. They concluded that the most likely explanation for historical poisoning incidents was a misidentification of I. torosus with Suillellus luridus, though they could not rule out the latter species containing a hitherto unidentified compound causing alcohol-related reactions.[27] No clinical cases of alcohol-related sensitivity have been recorded for I. torosus.[24]

Distribution and habitat

Imperator torosus is native to southern Europe east to the

Quercus calliprinos) in the Bar'am forest in Upper Galilee.[18] Fruitings typically occur from July to September in calcareous (chalky) soil, with fruit bodies appearing either singly or in small groups.[1]

Notes

  1. ^ Fries' Boletus pachypus is a synonym of Caloboletus radicans.
  2. ^ Type specimens were not necessary for a valid species description at this time.
  3. ^ Boletus luteocupreus and B. rhodopurpureus were also placed in this new genus.[23]

References

  1. ^ a b c d e f Alessio CL (1985). Boletus Dill. ex. L. Fungi Europaei (in Italian). Vol. 2. Saronno, Italy: Biella Giovanna. pp. 226–27.
  2. ^ "Boletus torosus Fr. & Hök: 10, 1835". MycoBank. International Mycological Association. Retrieved 22 March 2013.
  3. ^ Secretan L. (1833). P.A. Bonnant (ed.). Mycographie suisse, ou, Description des champignons qui croissent en Suisse, particulièrement dans le canton de Vaud, aux environs de Lausanne [Swiss Mycographie, or description of fungi growing in Switzerland, particularly in the canton of Vaud, near Lausanne] (in French). Vol. 3. Geneva, Switzerland. p. 24.
  4. JSTOR 1216724
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  5. JSTOR 1218449
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  6. ^ Fries EM, Hök CT (1835). Boleti, Fungorum Generis Illustratio [Boletes, Mushroom genera illustrated] (PDF) (in Latin). Uppsala, Sweden: Regiae Academiae Typographia. p. 10.
  7. ^ Fries EM (1838). Epicrisis Systematis Mycologici: Seu Synopsis Hymenomycetum [A Critical Study of Mycology: A Synopsis of the Hymenomycetes] (in Latin). Vol. 1–2. Uppsala, Sweden: Regiae Academiae Typographia. p. 417.
  8. ^ a b Bertolini V, Simonini G (2013). "Problemi nomenclaturali inerenti alla famiglia delle Boletaceae: I. Tipificazioni: Boletus torosus, Boletus rhodopurpureus e B. emilei" [Nomenclatural problems inherent to the family Boletaceae: I. Typification: Boletus torosus, Boletus rhodopurpureus and B. emilei]. Rivista di Micologia (in Italian). 2: 117–34.
  9. ISBN 978-0-521-86645-3
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  10. ^ "Recommended English Names for Fungi in the UK" (PDF). British Mycological Society. Archived from the original (PDF) on 16 July 2011. Retrieved 27 July 2015.
  11. ISBN 978-3-437-30436-1
    .
  12. ^ Tholl M-T (1985). "Notes mycologiques. Champignons intéressants récoltés au Grand-Duché de Luxembourg de 1980 à 1983" [Mycological Notes. Interesting mushrooms harvested in the Grand Duchy of Luxembourg from 1980 to 1983] (PDF). Bulletin de la Société des Naturalistes Luxembourgeois (in French). 85: 61–75.
  13. ^ Quélet L. (1886). Enchiridion Fungorum in Europa media et praesertim in Gallia Vigentium [Handbook of Mushrooms in central Europe, especially France] (in French). Lutetia: Octave Dion. p. 160.
  14. ^ Romagnesi H. (1976). "Nomenclature des bolets du groupe Purpureus Pers. ex Mich. ss. Fries" [Nomenclature of boletes in the group Purpureus Pers. ex Mich. ss. Fries]. Bulletin de la Société Mycologique de France (in French). 92 (3): 305–10.
  15. ^ Brillouet J-M, Brillouet T (1993). "Descrizione comparativa di raccolte di Boletus xanthocyaneus Ramain ex Romagnesi e di Boletus torosus Fries" [Comparative descriptions of collections of Boletus xanthocyaneus Ramain ex Romagnesi and of Boletus torosus Fries]. Rivista di Micologia (in Italian). 36 (1): 65–72.
  16. ^
    doi:10.1016/S0269-915X(97)80092-4
    .
  17. ^ Estadès A, Deïana JC (2004). "Boletus xanthocyaneus et Boletus torosus. Deux espèces distinctes" [Boletus xanthocyaneus and Boletus torosus. Two distinct species]. Bulletin Mycologique et Botanique Dauphiné-Savoie (in French). 127: 15–30.
  18. ^
    doi:10.1016/s0007-1536(72)80037-8
    .
  19. ISBN 978-0-85486-016-6
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  20. ^ Hlaváček J. (1996). "Přehled našich hub hřibotvarých (Boletales)" [Overview of our bolete mushrooms (Boletales)]. Mykologický Sborník (in Czech). 73 (3): 71–79.
  21. PMID 17682784
    .
  22. PMID 23931115
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  23. ^ a b Assyov B, Bellanger J-M, Bertéa P, Courtecuisse R, Koller G, Loizides M, Marques G, Muñoz JA, Oppicelli N, Puddu D, Richard F, Moreau P-A (21 May 2015). "Nomenclatural novelties". Index Fungorum (243).
  24. ^ a b c Flammer R. (2008). "Boletus torosus – Coprin und Alkohol" [Boletus torosus – Coprine and alcohol] (PDF). Schweizerische Zeitschrift für Pilzkunde (in German). 2008 (4): 146–47.
  25. ^ a b c d e Assyov B. (2013). "Boletus torosus". Boletales.com. Retrieved 25 July 2015.
  26. S2CID 84004250. Open access icon
  27. ^ a b Kiwitt U, Laatsch H (1994). "Coprin in Boletus torosus: Beruht die angebliche Alkoholunverträglichkeit durch den Verzehr des Netzstieligen Hexenröhrlings (Boletus luridus) auf einer Verwechslung?" [Coprine in Boletus torosus: Is the alleged alcohol hypersensitivity by ingestion of B. luridus caused by a mistake?] (PDF). Zeitschrift für Mykologie (in German). 60 (2): 423–30.
  28. ISBN 978-0-7167-2600-5
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  29. ^ Kiyashko A. "Boletus torosus var. torosus". The Global Fungal Red List Initiative. IUCN. Retrieved 15 February 2022.
  30. ^ Joint Nature Conservation Committee (15 December 2010). UK priority species pages – Version 2. Boletus torosus Fr. & Hök (PDF) (Report).
  31. ^ Kasom G, Miličković N (2010). "Protected species of macrofungi in Montenegro" (PDF). Natura Montenegrina, Podgorica. 9 (2): 195–203. Archived from the original (PDF) on 2016-03-04.
  32. S2CID 234834743
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  33. hdl:2437/314359
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