Cystoderma carcharias

Cystoderma carcharias
Scientific classification
Kingdom:	Fungi
Phylum:	Basidiomycota
Class:	Agaricomycetes
Order:	Agaricales
Family:	Agaricaceae
Genus:	Cystoderma
Species:	C. carcharias
Binomial name
Cystoderma carcharias (Pers.) Fayod
Synonyms
Agaricus carcharias Agaricus granulosus var. carcharias Lepiota carcharias[1]

Cystoderma carcharias
Mycological characteristics
	gills on hymenium
	cap is convex or flat
	or adnate
	stipe has a ring
	spore print is white
	ecology is saprotrophic
	edibility: inedible

Cystoderma carcharias, is a species of basidiomycete fungus of the genus Cystoderma. A rare fungus, it has a widespread distribution, and has been collected in coniferous forests in Asia, Australia, Europe, and North America. In the field, it can be characterized by a pink cap up to 6 cm (2.4 in) broad, a well-developed ring on the stem, and an unpleasant odour.

Taxonomy

The species was first described scientifically by Christian Hendrik Persoon, who named it Agaricus carcharias in 1794.^[2] Swiss mycologist Victor Fayod assigned it its current name in 1889.^[3] The specific epithet carcharias is probably derived from the Greek καρχαρός (karcharos) which means sharp, pointed or jagged. Interestingly, καρχαρίας (karcharias) is literally translated as shark.

Description

The fruiting body of Cystoderma carcharias is a relatively small agaric. The fruiting body is characterised by an off-white and pale pink-tinged cap with a distinct darker central spot, and a powdery cuticle. The cap is at first convex, but with maturity becomes flat and slightly umbonate. The cap is up to 6 cm (2.4 in) in diameter and may bear a margin fringed with remnants of a partial veil. The gills are white, adnate and crowded. The stem is white and smooth above, and granular below a white, upturned, flared and persistent ring. The stem is cylindrical and up to 7 cm (2.8 in) tall. The flesh is white, firm and full throughout.^[4][5] Additionally, C. carcharias forma album is a form recognised as having a snow-white cap.^[6]

Under a microscope, the spores are seen ellipsoid in shape, with dimensions 4–5.5 by 3–4 µm. The spores are white and amyloid. The basidia are 4-spored,^[4][5][7] club-shaped, and measure 20–25 by 4–6 µm.^[8]

The fruiting body of C. carcharias bears a characteristic strong, unpleasant odour. The odour has been described as earthy, muddy and mouldy by various authors. This has been attributed to the presence of the compound geosmin.^[9] The taste is not distinctive.

Cystoderma carcharias is a rare fungus distributed in Europe, North America and temperate Asia,^[8] occurring only in coniferous forests. It has also been found in Australia.^[10] Fruiting bodies are found singly or in groups on soil among grass or moss during late summer and autumn. The fungus is an acidophilic litter saprotroph.

This fungus has been deemed inedible by various authors.^[4][11] The unpleasant odour, relatively small fruiting body and sporadic occurrence are probable reasons why this mushroom is regarded as inedible.

References

1. ^ "Cystoderma carcharias taxon record details at Index Fungorum". CAB International. http://www.indexfungorum.org/Names/SynSpecies.asp?RecordID=357219. Retrieved January 11, 2010. 
2. ^ Persoon CH. (1794). "Dispositio methodica fungorum" (in Latin). Neues Magazin für die Botanik, Römer 1: 81–128. 
3. ^ Fayod MV. (1889). "Prodrome d'une histoire naturelle des Agaricinés" (in French). Annales des Sciences Naturelles, Botanique. VII 9: 351. 
4. ^ ^{a b c} Jordan M. (1995). The Encyclopedia of Fungi of Britain and Europe. London: David & Charles. p. 214. ISBN 0-7153-0129-2. 
5. ^ ^{a b} Gerault, Alain (October 2005). Florule Evolutive des Basidiomycotina du Finistere – Heterobasidiomycetes – Tricholomatales (in French). 2.1. http://projet.aulnaies.free.fr/Florules/TRICHOLOMATALES.pdf. 
6. ^ "Trial field key to the species of Cystoderma in the Pacific Northwest". Pacific Northwest Key Council. http://www.svims.ca/council/Cystod.htm. Retrieved January 30, 2010. 
7. ^ Saar I, Põldmaa K, Kõljalg U. (2009). "The phylogeny and taxonomy of genera Cystoderma and Cystodermella (Agaricales) based on nuclear ITS and LSU sequences". Mycological Progress 8: 59–73. 
8. ^ ^{a b} Saar I. (2003). "The genera Cystoderma and Cystodermella (Tricholomataceae) in temperate Eurasia". Mycotaxon 86: 455–73. http://www.cybertruffle.org.uk/cyberliber/59575/0086/0455.htm. Retrieved 2010-01-29. 
9. ^ Tkacz J. S., Lange L. (2004). Advances in fungal biotechnology for industry, agriculture, and medicine. Springer. p. 342. ISBN 0306478668. 
10. ^ Dennis RWG. (1980). "Micro fungi of St. Kilda Australia". Kew Bulletin 34 (3): 742–44. 
11. ^ Polèse J., Deconchat C. (2002). Champignons. L'encyclopédie. Losange: Editions Artemis. p. 245. ISBN 2-84416-145-6. 

External links

• Cystoderma carcharias in MycoBank.
• Cystoderma carcharias in Index Fungorum.
• Scientific images at BioImages (UK)