Arachnion

The genus was circumscribed by Lewis David von Schweinitz in 1822 with Arachnion album as the type, and only species.[3] The genus name is Greek for "cobweb".

William Chambers Coker and John Nathaniel Couch circumscribed the family Arachniaceae in 1928 to contain Arachnion.[4] The genus was later placed in the now-defunct family Lycoperdaceae.[5] Modern molecular analysis has shown that Arachnion, as well as other puffball genera, are part of the family Agaricaceae.[6]

Arachnion species have a characteristic gleba, resembling a mass of grainy, sand-like particles. At a microscopic scale, the granules are peridioles, or tiny sacs made of hyphae that contain spores. Inside each sac is a minuscule chamber that contains inward-facing basidia (spore-bearing cells), an arrangement similar to that seen in Lycoperdon. The fruitbodies have a smooth, thin, and fragile peridium that readily disintegrates into small pieces in maturity to expose the granular contents.[4]

The genus is widely distributed, with species found in Australia, North and South America, South Africa, and Europe, and Japan.[7]

As of January 2016, Index Fungorum accepts 11 species in Arachnion:[8]

• Arachnion alborosellum Verwoerd 1926 – South Africa[9]
• Arachnion album Schwein. 1822[3]
• Arachnion bovista (Mont.) Mont. 1849[10]
• Arachnion firmoderma Verwoerd 1926 – South Africa[9]
• Arachnion foetens Speg. 1906 – South America[11]
• Arachnion iriemae Rick 1961
• Arachnion iulii Quadr. 1996 – Italy[12]
• Arachnion lazoi Demoulin 1972[13]
• Arachnion lloydianum Demoulin 1972[13]
• Arachnion rufum Lloyd 1906[14]
• Arachnion scleroderma Lloyd 1915[15]

• List of Agaricaceae genera
• List of Agaricales genera