Agaricus deserticola
Mycotaxon 112: 292. 2010.
Common Name: none
Synonyms: Secotium texensis Berkeley & Curtis; Longula texensis (Berkeley & Curtis) Zeller; Longia texensis (Berkeley & Curtis) Zeller; Agaricus texensis (Berkeley & Curtis) Geml, Geiser & Royse
Cap 4-10 cm tall, 4-7 cm broad, subglobose, ovoid or convex; margin fused to the stipe for most of development, at maturity sometimes pulling partially away; surface dry, at first nearly glabrous, soon breaking up into appressed to raised, tan or brown scales, revealing an underlying whitish context, the latter firm, fleshy, bruising yellowish; in age the cap and context drying becoming tough, brittle, tending to split longitudinally, exposing contorted gill tissue.
Gills consisting of tightly packed, contorted, fused plates with intervening cavities, at first pallid, becoming brownish, finally blackish-brown; free from the stipe.
Stipe 4.0-7.0 cm tall, 2.0-3.0 cm thick, variably shaped: equal, tapered to a narrowed or an enlarged base; surface glabrous to fibrillose-striate, sometimes conspicuously striate, pallid to cream, bruising or discoloring tawny-brown in age; veil two-layered, at first sheathing, rupturing with elongation of the fruiting body leaving an inconspicuous scar low to central on the stipe, or forming a scaly ring high on the stipe or alternatively the veil remaining partially attached to the pileus margin.
Spores 5.5-7.0 x 5.0-6.0 µm, globose to broadly ellipsoid, smooth, thick-walled, germ pore not evident, hilar appendage inconspicuous; spores blackish-brown.
Solitary to gregarious on disturbed ground, dry waste areas, e.g. roadsides, edges of agricultural fields, etc.; uncommon in the San Francisco Bay Area, occasional in the Central Valley; fruiting in the spring.
Unknown.
Agaricus deserticola is a mushroom of dry, open habitats, believed to have evolved from a moisture-loving Agaricus ancestor. Agaricus features are still apparent though modified, presumably to aid survival in an arid environment. These include a cap that no longer expands, blackish-brown, crumpled, gills that don't forcibly discharge spores, and a partial veil that remains intact even at maturity. This type of development is called secotioid or sequestrate, with examples known from a number of genera of gilled and boletaceous mushrooms. Two such fungi that resemble Agaricus deserticola are Podaxis pistillaris and Montagnea arenaria. Both are found primarily in the desert regions of California. Podaxis pistillaris has an elongated, scaly cap, much like a shaggy mane, Coprinus comatus, but is not deliquescent and despite the similarities, probably is not closely related. Montagnea arenaria is a stalked puffball distantly allied to Coprinus. It has a woody stipe which emanates from a volva cup, and is crowned by thin umbrella of crumpled, blackish gill-like tissue.
Arora, D. (1986). Mushrooms Demystified. Ten Speed Press: Berkeley, CA. 959 p.
Berkeley, M.J. (1873). Notices of North American Fungi. Grevillea 2(14): 33-35. (Protologue)
Desjardin, D.E., Wood, M.G. & Stevens, F.A. (2015). California Mushrooms: The Comprehensive Identification Guide. Timber Press: Portland, OR. 560 p.
Geml, J., Geiser, D.M. & Royse, D.J. (2004). Molecular evolution of Agaricus species based on ITS and LSU rDNA sequences. Mycological Progress 3(2): 157-176.
Kerrigan, R.W. (2016). Agaricus of North America. New York Botanical Garden: Bronx, NY. 574 p.
Moreno, G, Esqueda, M., Pérez-Silva, E., Herrera, T. & Altés, A. (2007). Some interesting gastroid and secotioid fungi from Sonona, Mexico. Persoonia 19(2): 265-280.
Moreno, G., Lizárraga, M., Esqueda, M. & Coronado, M.L. (2010). Contribution to the study of gasteroid and secotioid fungi of Chihuahua, Mexico. Mycotaxon 112(1): 291-315.
Zeller, S.M. (1941). Further notes on fungi. Mycologia 33: 196-214.
Zeller, S.M. (1943). North American species of Galeropsis, Gyrophagmium, Longia, and Montagnea. Mycologia 35: 409-421.
