Fungi Key – Agaricus

This is a trial key for Queensland Agaricus.
QMS would greatly appreciate your feedback: info [at] qldfungi.org.au
1. Stipe yellowing distinctly when scratched 2
1.* Stipe reddening, browning or not changing colour when scratched 4
2. Cap white, cream, or occasionally pale greyish-brown, cap yellowing when scratched, at least at margin Agaricus xanthodermus
2.* Cap covered in dark brown to grey brown small squamules or fibrils, only lower half of stipe strongly yellowing when scratched 3
3. Fruiting bodies almost black when young, radially splitting at maturity Agaricus rotalis*
3.* Young fruiting bodies grey brown, only occasionally splitting at maturity Agaricus moelleri
4. Stipe with a broad ring, >35 mms diameter with floccules or warts below 5
4.* Ring < 35mms, or if larger then without floccules or warts on its lower side 6
5. Cap covered with yellow brown to brown squamules on paler background Agaricus augustus
5.* Cap white discolouring yellowish brown with age or on handling, glabrous or covered with minute concolourous fibrils Agaricus arvensis*
6. Cap with purple, vinaceous or brown-vinaceous fibrils or squamules 7
6.* Cap white, cream or brownish, fibrillose, squamulose or glabrous 10
7. Cap fibrillose at centre, but elsewhere covered in broad, adpressed red brown to brown-vinaceous squamules, spores 7-9 µm long Agaricus langei
7.* Cap uniform fibrillose or covered in narrow squamules, spores < 7 µm long 8
8. Cap large, 50 – 100 mms diameter, plano convex, later applanate, flesh reddening or browning on cutting Agaricus austrovinaceus
8.* Cap smaller, 30 – 60 mms diameter, convex, flesh yellowing slightly or unchanging on cutting 9
9. Spores 5.3 × 3.5 on average Agaricus dulcidulus
9.* Spores 7 × 4.4 on average Agaricus sp. 1
10. Stipe with bulbous base and height generally = or > cap diameter Agaricus impudicus
10.* Stipe without bulbous base 11
11. Cap brownish, ring triangular, lamellar edge sterile, basidia 2-spored Agaricus bisporus
11.* Cap white to cream, ring thin, lamellar edge fertile, basidia 2 or 4-spored 12
12. Stipe height < cap diameter, ring thin, lamellar edge fertile, basidia 4-spored Agaricus campestris
12.* Stipe height > cap diameter, ring ephemeral, basidia 2 and 3 spored Agaricus sp. 5

Notes

1. * no Queensland material but probably present.
2. Agaricus dulcidulus also recorded in Queensland under its synonym A. semotus
3. Agaricus moelleri recorded in Australia under its synonym A. praeclarosquamosus

Pat Leonard
21 September, 2013