Agaricus coccineus Kuo sp. nov.

[ Basidiomycetes > Agaricales > Agaricaceae > Agaricus . . . ]

by Michael Kuo

One of the truly rewarding experiences involved with running a popular mushroom identification Web site is the opportunity to discover new species among the many mushrooms and photographs sent in by collectors who want help identifying their finds. While stinkhorns and flower-pot parasols constitute the bulk of my "What's this mushroom?" e-mails, I occasionally receive truly fascinating, never-before-seen species. On April 1 of this year, for example, Dorothy in Visalia, California, found the illustrated mushrooms under conifers in her yard, and sent photos after searching fruitlessly in field guides and on the Internet for anything similar.

I was floored. The mushroom is obviously an Agaricus, given its stature, its chocolate brown gills, and its ring. But brightly colored Agaricus species are rare; almost all of them are whitish or brownish, with the exception of a few yellow and orange species described from the southeast. Dorothy had discovered something truly new to mycology!

So, while this Web site is not a peer-reviewed publication accepted by the mycological community for the naming of new species, I have no problem naming this new species Agaricus coccineus (the scarlet Agaricus). And since the description below follows the protocol for authoring new species, I hope the mycological community will accept this name as a "sp. nov." (new species), rather than a "nom. prov." (provisional name).

I have also included, below the description, my e-mail correspondence with Dorothy; these communications are integral to understanding the species.

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Agaricus coccineus Kuo sp. nov.

Statura campestroidia; pileus 10 cm latus, coccineus, convexus; stipito aequo, 3.5 cm longo; annulo superiore vel medio; sporae 5.5-8.5 x 4-6.5 µ. Specimen typicum in Herbarium MushroomExpertum conservatum; legit prope Visalia, Tula County, California, 1 April 2004.

Stature campestroid; known only from the type locality, under Pinus, in Tula County, California; pileus 10 cm wide, convex, smooth, scarlet; lamellae at maturity chocolate brown, close, free; stipe 3.5 cm long by 1.5 cm wide, equal overall but tapering to base, white, not bruising; partial veil leaving a superior to median, collapsing annulus; context white unchanging; odor none; taste mild; basidia 2-spored; basidiospores 5.5-8.5 x 4-6.5 µ.

Observations: The scarlet cap color is previously undocumented in any Agaricus and easily serves to separate the species.

Correspondence with Collector:

April 1, 2004:

"Dear Mushroom Expert, This mushroom was found by one of our Pine trees in The Central San Joaquin Valley of California in Visalia, CA, 93277. I have spent several hours trying to ID it. I have a small field guide that proved useless and spent a great deal of time searching the Internet. I looked at great length on your web site, to no avail. Please let me know what this is & if it is edible. Thanks so much, Dorothy."

April 3, 2004:

"Dorothy, Thanks for your e-mail. Your mushroom isn't one I recognize at sight--but I am not very familiar with California mushrooms. I would need more information about the mushroom to be able to hazard much of a guess: its spore print color, what its gills look like... and possibly other things. Best wishes, Michael."

April 14, 2004:

"Hello Michael, I regret that I wasted your time on this. The mushroom was placed in my front yard as an April Fool's prank. It was a Portabella painted red. Little did my friend know that I compulsively try to identify the unfamiliar. Sorry, I feel very silly. Dorothy."

April 14, 2004:

"Dorothy: LOL!!!! Don't feel silly. I quite enjoyed this exchange. What I didn't write before was that, not only did I not recognize it, but it looked VERY interesting. "That looks like an Agaricus with a bright red cap," I thought to myself. "Not possible." I had visions of your having accidentally discovered a new and rare Agaricus, and thought about writing that I wanted you to dry the thing and send it to me. Then I decided that I must be wrong about Agaricus, that it must be some western 'shroom I didn't know. So your friend got me, too. Michael."

Cite this page as:

Kuo, M. (2004, April). Agaricus coccineus. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/agaricus_coccineus.html