What You Should Know
Geopora arenosa is part of the genus Geopora in the family Pyronemataceae. It is a small dark partially buried cup. Margin may split. Inside surface pale, outer surface dark, hairy.
Poisonous if eaten raw, Geopora arenosa may be toxic even if cooked. In any case, the flesh is insubstantial and, given the relative rarity of these cup fungi in many areas, it would seem irresponsible to gather them.
Geopora arenosa Mushroom Identification
Fertile (inner) surface
Pale cream to grayish beige on the smooth inner (hymenial or spore-bearing) surface, fruitbodies of Geopora arenosa develop over several months as underground spheres before breaking through the surface of the soil and splitting open in the form of typically 5 to 7 fairly regular rays. Up to 2cm tall, the cups are typically 1 to 2cm across when fully open.
Infertile (outer) surface and stem
Varying in color from pale-brown to mid-brown, the scurfy outer surface is infertile and is covered in microscopic light-brown hairs. (The spores are produced on the shiny inner surface of the cup.)
Is Typically 300µm x 22 µm, with eight spores per ascus.
Ellipsoidal-fusiform, smooth, typically 28 x 17µm; each usually containing one or more often two large oil drops and some small ones.
On sandy soil, often in coastal dune systems. Geopora species are thought to be mycorrhizal with various shrubs, but it is reportedly very difficult to determine with certainty the species involved.
September to November.
Geopora arenosa Look-Alikes
Is similar but rather paler; it also appears in dry sandy places, most particularly on dune systems.
Has a more hairy outer surface and grows exclusively (or almost so) under cedar trees (Cedrus spp.).
The bright red mushroom that grows on dead twigs and branches, in mossy woods, and sometimes under damp hedgerows.
Geopora arenosa Taxonomy& Etymology
Originally described in 1881 by Karl Wilhelm Gottlieb Leopold Fuckel (1821 - 1876) and named Peziza arenosa, this cup fungus was for many years known as Sepultaria arenosa, a name given to it in 1907 by Jean Louis Emile Boudier (1828 - 1920). Its present accepted name, Geopora arenosa, dates from a monograph by S Ahmad (1910 - 1983) published by the Biological Society of Pakistan in 1978.
The generic name Geopora means earth cup, appropriate for cup fungi that grow on/in the earth, while the specific epithet arenosa means 'of sand'. The synonymous generic name Sepultaria means underground tomb, and as the cup fungi in this group develop underground and are usually more than half buried even when the cups have opened, the reference seems entirely appropriate.
Geopora arenosa Synonyms
Humaria arenosa Fuckel, Jb. nassau. Ver. Naturk. 23-24: 321 (1870) [1869-70]
Lachnea arenosa (Fuckel) Sacc., Syll. fung. (Abellini) 8: 167 (1889)
Lachnea arenosa (Fuckel) Sacc., Syll. fung. (Abellini) 8: 167 (1889) var. arenosa
Peziza arenosa (Fuckel) Cooke, Mycogr., Vol. 1. Discom. (London)(no. 2): 66, fig. 117 (1876)
Peziza arenosa (Fuckel) Cooke, Mycogr., Vol. 1. Discom. (London)(no. 2): 66, fig. 117 (1876) var. arenosa
Peziza arenosa var. bloxamii Cooke, Mycogr., Vol. 1. Discom. (London)(no. 2): 68 (1876)
Sarcosphaera arenosa (Fuckel) Lindau, Nat. Pflanzenfam., Teil. I (Leipzig) 1(1): 182 (1897)
Scutellinia arenosa (Fuckel) Kuntze, Revis. gen. pl. (Leipzig) 2: 869 (1891)
Sepultaria arenosa (Fuckel) Boud., Hist. Class. Discom. Eur. (Paris): 59 (1907)
Sepultaria arenosa (Fuckel) Boud., Hist. Class. Discom. Eur. (Paris): 59 (1907) var. arenosa
Sepultaria arenosa var. dodgei Rehm, in Dodge, Trans. Wis. Acad. Sci. Arts Lett. 17(2): 1050 (1914)
Photo 1 - Author: csyampae (Attribution-NonCommercial 4.0 International)
Photo 2 - Author: huafang (Attribution-NonCommercial 4.0 International)
Photo 3 - Author: merav (Attribution-NonCommercial 4.0 International)
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