Kerrigan Flipbook REVIEW

AGARICUS
of NORTH AMERICA
RIC HA RD W. KE RRIGA N



Agaricus of North America

Richard W. Kerrigan

Memoirs of The NewYork Botanical Garden,Volume 114
Bronx, New York, USA

Table of Contents xiii
xvii
Acknowledgments
1
Why This Book? Why Now? The author’s foreword 3
5
Agaricus in the World 11
17
Agaricus in Commerce 17
21
The Genus Agaricus: History and Nomenclature 21
32
The Literature of Agaricus: The State of Knowledge 41
41
To Study and Identify Agaricus 47
What Is the Objective? 49
Study and Identification 49
Macroscopic Features 50
Microscopic Features
Ecological and Geographical Attributes 51
Biochemical Characters 53
Other Modern Characters
Cultural Characters 55
Summary 57

Further Notes on Formats and Conventions Used in This Book 61

“To eat wild mushrooms . . .” 62
Special Note on Edibility and Responsibility
65
Note on Phylogenetic Analysis
69
Sequences Representing Sections (Also Subsections and Unnamed 70
Major Lineages) of Agaricus in the Phylogenetic Trees 74
76
Typification of Published Taxa 78
Agaricus abruptibulbus, A. agrinferus, A. amicosus, A. andrewii, 80
A. campestris, A. crocodilinus, A. cuniculicola, A. haemorrhoidarius 82
var. fumosus, A. variabilis, Polyplocium californicum

Keys to Agaricus of North America
I. Dichotomous Key for the Placement of Agaricoid and Secotioid
Specimens of Agaricus Subgenus Agaricus in North America to
Sections or Groups
II. Quasi-Synoptic Key for the Placement of Specimens of
Agaricus Subgenus Agaricus in North America to Sections or Groups

Agaricus [Subgenus Agaricus]
Agaricus Section Bivelares
Agaricus Subsection Hortenses
A. bisporus var. bisporus
A. bisporus var. burnettii
A. sipapuensis sp. nov.
A. agrinferus
A. subfloccosus

A. devoniensis subsp. devoniensis T able of C onte nt s vii
A. devoniensis subsp. bridghamii
A. bitorquis 84
A. subsubensis 86
A. sp. ‘RWK 1789’ 88
A. subperonatus 90
Agaricus Subsection Cupressorum 92
A. cupressophilus 94
A. tlaxcalensis 96
Other Entities in Section Bivelares 98
A. villaticus Brondeau sensu Isaacs 100
A. ‘brevistipus’ (Isaacs nom. prov.)
A. sterlingii 102
A. brunnescens 102
102
Agaricus Section Chitonioides 102
A. bernardi
A. pilosporus 105
A. vinaceovirens 108
A. gennadii 110
A. bernardiformis 112
A. pequinii 114
A. sp. ‘the Palmer collection’ 116
A. sp. ‘GQ-3’ 118
120
Agaricus Section Xanthodermatei 122
Agaricus Subsection Xanthodermatei
A. xanthodermus 123
A. malangelus sp. nov. 127
A. californicus 132
A. arizonicus sp. nov. 134
A. placomyces 136
A. approximans 138
A. cf. approximans 140
A. hybrid ‘RWK 2023’ 144
A. berryessae sp. nov. 146
A. deardorffensis sp. nov. 150
A. leptocaulis sp. nov. 152
A. iodosmus 154
A. endoxanthus 156
A. pocillator 158
A. tollocanensis 160
A. sp. ‘RWK 1007’ 162
[Group linked to A. pseudopratensis] 164
A. buckmacadooi sp. nov. 166
A. kriegeri sp. nov.
Agaricus Subsection Hondenses subsect. nov. 168
A. hondensis 170
A. subrufescentoides 172
174
176

viii T able of C onte nt s 178
178
Other Entities in Section Xanthodermatei 180
A. glaber 181
A. cervinifolius 181
A. “praeclaresquamosus”: Concepts from Western North America 182
A. sp. ‘RWK 741’ 183
A. sp. ‘RWK 2125’ 183
A. ‘crassistipus’ (Isaacs nom. prov.) 183

Excluded Taxa 185
A. placomyces var. microsporus 188
A. placomyces var. flavescens 192
194
Agaricus Section Sanguinolenti 196
Agaricus Subsection Sylvatici 198
A. rubronanus 200
A. sp. ‘RWK 2013’ 202
A. sp. ‘RWK 1335’ 204
A. bivelatoides; A. collection RWK 1171 206
A. benesii sensu lato 208
A. cf. benesii 210
A. sylvaticus subsp. occidentalis subsp. nov. 212
A. sylvaticus subsp. cf. occidentalis: California Variant
A. cordillerensis sp. nov. 214
A. hupohanae sp. nov. 216
A. thujae sp. nov.
[Possibly affiliated species] 218
A. arorae 219
A. sp. ‘RWK 1208’ 219
Other Entities in Subsection Sylvatici 221
A. albosanguineus 223
A. haemorrhoidarius sensu Peck 223
A. haemorrhoidarius var. fumosus 223
A. collection Pg 317 #20 224
A. haemorrhoidarius sensu Murrill 224
A. haemorrhoidarius sensu Smith 226
A. sylvaticus sensu Hesler 228
A. sylvaticus sensu Atkinson 230
A. sp.: West Virginia collections
Agaricus Subsection Bohusia 233
A. brunneofibrillosus sp. nov. 234
A. amicosus 236
238
Agaricus Section Nigrobrunnescentes 242
Agaricus Subsection Nigrobrunnescentes stat. nov. 244
A. eludens (provisional placement) 246
Agaricus Subsection Pattersonia subsect. nov. 248
A. pattersoniae
A. fuscovelatus
A. sp. ‘RWK 1583’
A. lilaceps

T able of C onte nt s ix

A. laparrae sp. nov. 250
A. sp. ‘A.G.’ 252

Other ‘sanguinolent’ Lineages: The ‘tennesseensis’ and ‘TRc’ Lineages 253
A. tennesseensis sp. nov. 256
A. sp. ‘ASM 13217’ 258
A. sp. ‘NY 49276’ 260

Agaricus Section Agaricus 263
[Main lineage]
A. cf. campestris 270
A. gastronevadensis sp. nov. 272
A. andrewii 274
A. argenteus subsp. argenteus 278
A. argenteus subsp. annetteae subsp. nov. 280
A. pampeanus (A. solidipes Peck 1904, nom. illeg.) 282
A. aristocratus 284
A. incultorum sp. nov. 286
A. sp. ‘RWK 807’ 288
A. porphyrocephalus var. porphyrocephalus 290
A. porphyrocephalus var. pallidus var. nov. 292
A. moellerianus 294
A. cf. altipes 296
A. griseicephalus sp. nov. 298
A. cf. cappellii 300
A. cf. chionodermus 302
A. sequoiae 304
[Basal lineage(s)]
A. rubribrunnescens 306
A. erindalensis sp. nov. 308
A. depauperatus 310
A. argyropotamicus 312
Other Entities in Section Agaricus
A. projectellus 314
A. praerimosus 314
A. spp. ‘RWK 1923’ and ‘PBM 2580’ 318
A. ‘pinyonensis’ (Isaacs nom. prov.) 319

Agaricus Section Spissicaules 321
A. cf. litoralis 326
A. bellanniae sp. nov. 328

Other Entities Possibly in Section Spissicaules 330
A. sp. ‘Isaacs 1298’ (as A. annae) 331
A. placomyces var. microsporus
333
Agaricus Section Subrutilescentes sect. nov. 336
A. subrutilescens 338
A. vinosobrunneofumidus sp. nov. 340
A. thiersii sp. nov.

x Table of Contents 342

Other Entities in Section Subrutilescentes 343
A. collection RWK 1320 346

Agaricus Section Rarolentes sect. nov. 349
A. butyreburneus sp. nov. 354
356
Agaricus Section Minores 358
A. comtulus 360
A. micromegethus 362
A. kerriganii (A. semotus sensu auct.) 364
A. diminutivus 366
A. comptuloides 368
A. auricolor Krieger (nom. illeg.)
A. sp. ‘RWK 2014’ 370
A. stevensii sp. nov. 370
371
Other Entities in Section Minores 372
A. collection RWK 916 372
A. collection RWK 652 373
A. citrinidiscus 373
A. collection RWK 1322 374
A. comtuliformis 374
A. cylindriceps var. aureus 375
A. sulphureiceps 375
A. collection WRWV05-440 375
A. collection RWK 2022 376
A. sp. ‘RWK 2282’ 377
A. sp. ‘CA636’
A. sp. ‘RWK 2118’ 378
A. placomyces var. flavescens
A. friesianus 379

Taxon of Uncertain Placement 390
A. placomyces var. microsporus 392
394
Agaricus Section Arvenses 396
[The pigmented sylvan group] 398
A. augustus 400
A. nanaugustus sp. nov. 402
A. julius sp. nov. 404
A. perobscurus 406
A. subrufescens
A. flavitingens 408
A. smithii 412
A. cuniculicola 416
A. rhoadsii
[The pale, primarily pastoral (sometimes sylvan) group]
A. crocodilinus
A. arvensis
A. fissuratus

T able of C onte nt s xi

[The pale sylvan group] 420
A. sylvicola 422
A. cretacellus 426
A. cruciquercorum sp. nov. 428
A. abruptibulbus 434
A. reducibulbus sp. nov. 436
A. moronii sp. nov. 438
A. sandianus sp. nov. 440
A. sp. ‘RWK 2283’ 442
A. summensis 446
A. albolutescens 448
A. didymus sp. nov. 452
A. gemellatus sp. nov. 454
A. inapertus 456
A. mesocarpus sp. nov. 458
A. diospyros sp. nov. 460
A. hybrid ‘RWK 2021’
462
Other Entities in Section Arvenses 463
A. fabaceus 463
A. magniceps 465
A. variabilis 467
A. amygdalinus 469
A. arvensis var. palustris 469
A. sp. ‘RWK 2049’ 470
A. cf. tenuivolvatus 471
A. sp. ‘RWK 1978’ 472
A. cf. macrocarpus
A. sp. ‘RWK 2214’ 477
478
Other Lineages Not Yet Named, Possibly Not Originating Within 480
the Accepted Monophyletic Sections 482
484
The ‘floridanus’ Lineage 486
A. floridanus 488
A. sp. ‘RMC 1256’ 490
492
The ‘longuloid’ and ‘gyrophragmioid’ Lineages 493
A. deserticola 494
A. sp. ‘RWK 1048’
A. evertens sp. nov. 497
A. zelleri nom. nov. 498
Araneosa columellata 508
511
The ‘martineziensis’ Lineage 513
A. martineziensis

Other Species in the Literature
The Agaricus (sensu strictu) Contributions of C. H. Peck
The Agaricus Contributions of W. A. Murrill
The Agaricus Contributions of A. H. Smith
The Agaricus Contributions of B. F. Isaacs
The Agaricus Contributions of A. E. Freeman

xii T able of C onte nt s 517
524
Literature Cited 525
Types Critically Examined 536
Vouchers Studied and/or Sequenced, and Accepted
Nomenclatural Citations: Species and Infraspecific Taxa Presented in This Work 568
Index to Scientific Names Now (or Formerly) Assigned to Agaricaceae,
With Prior Homonyms

Why This Book? Why Now?

The author’s foreword

There is no single guide, technical reference, or monograph to Agaricus in North America, nor
to any of our three countries here, nor, with few exceptions, to any region of the continent.
This regrettable oversight by modern civilization is clearly an impediment to preparing an ade-
quate inventory of biodiversity here, to say nothing of dining out with a measure of confidence.

During the 45 years I’ve been working on this genus, very few papers have appeared on
Agaricus in North America, and most of those, at least for the United States and Canada, have
been mine. Though available, this literature has not been commonly or easily obtainable by the
generalist mycophile. An authoritative and accessible sourcebook is, I think, highly desirable.

I have not written a field guide, although I think this book might serve in that role (if
one skims over the most technical information). Nor have I written a classic monograph, which
is to say a compendium of examinations of the vast number of herbarium specimens, includ-
ing type specimens, strewn across North America, for various reasons. I have attempted to write
accessibly about real and documented biodiversity, primarily for an imagined audience pos-
sessing interest and aptitude, if not always knowledge and experience, by providing consider-
able “how” and “why” explanations in addition to the technical details required by expert
taxonomists.

A complete inventory of Agaricus collections recorded in North American (and other)
herbaria would be as impractical as it would be unhelpful (for reasons that will become clear).
To try to usefully examine all that material would be to court madness. While I have evalu-
ated numerous type specimens, as needed, and have examined considerable additional herbar-
ium material when useful, I have also often accepted the competent reports on types prepared
by those who came before. Freeman (1979a, 1979b), Smith (1940, 1944a), and to some extent
Isaacs (1963, 1967) and predecessors have already done a great deal of the work. Some further
critical studies suggested in this text I have chosen, at least for the moment, to flag and to leave
to those who will follow, when more new collections and expanding toolkits will be available.

My own approach has been to evaluate Agaricus diversity in terms of living members of
natural ecosystems, and as elements of a complex pattern of phylogenetic relationships, supported
by modern collections and also by historical collections when practical. Here you will find that
perspective, combined with complete technical descriptions (when available) and my own notes
and pointers to particular herbarium collections, observations, sequences, speculations, future
inquiries, and the like. What I have attempted to produce is a monographic technical resource that is
authoritative, while remaining generally accessible, and is comprehensive to the extent that our
existing knowledge allows. In particular, much of the information I present in this work is pro-
vided to allow the nonspecialist and interested amateur to understand not only how, but why,
various taxonomic, nomenclatural, and phylogenetic practices are employed. I believe that this
presentation uniquely bridges a gap between the typical specialist literature and the typical field
guide, in a way that will interest many readers.

This volume is in no sense a monument to anything, but rather a testament to the con-
tinuing process of comprehending the unknown. It is a tool, not logos. It is far from perfect or
complete, I well know. Some limitations in this treatment exist for reasons that are exciting:
there surely remain large numbers of unknown, unnamed, undescribed species of Agaricus in
North America. We may have been as much as a century behind Europe in taking inventory,
though the gap is rapidly closing. We need feet on the ground, and you may own the feet that
will discover some portion of the unplumbed reservoir of diversity that these shores harbor.
Some reasons are challenging: Agaricus is a difficult, subtle, phenotypically plastic genus with

xvii

xviii W hy T h i s B ook ? W hy N ow ?

many, many rare and seemingly cryptic species, and North America is a big and diverse conti-
nent. For some subgroups, the nomenclature itself may not approach stability for several more
years. And some reasons are mundane, of the dog-ate-my-homework variety: certain of my
specimens have incomplete notes, poor photos, were collected under difficult circumstances,
were described on the fly without critical characters, were destroyed by fire, were very unfor-
tunately discarded while stored at an institution pending critical study and herbarium acces-
sion, were photographed on film lost or mutilated during processing or on memory cards that
failed, and so on (all true).

The present volume is comprehensive in the sense that it attempts to encompass all that
is known about Agaricus in North America (at least, north of the 30th parallel). However, it is
just a start, a down payment on what we as stewards of the commons deserve: an exhaustively
comprehensive, absolutely authoritative summary of Agaricus in North America. It is a part of
the complex ongoing process of discovering, naming, and communicating information about
these mushroom species. The process is far from completed.

And that’s the good news. This subject is not a done deal; rather it presents an opportu-
nity for interested parties to make a contribution to a difficult, neglected area of research on
fungal biodiversity. That is exactly why I was attracted to the problem of Agaricus in 1971, and
why I hope that it will intrigue and inspire many of you who read this, that it may foster
future contributions that collectively will surpass this one. By acknowledging the unknown
while presenting the known as accessibly as possible, I am inviting you to help make future
editions of this work, or subsequent works, better than what is possible now. You should an-
ticipate Agaricus frustrations, goads to inquiry and discovery, which I long ago made uneasy
friends with. I hope that you will enjoy this book, and that the surprises neither of us can now
anticipate will delight you all the more when you encounter them. If, instead, your tempera-
ment is such that you prefer checklists, I suggest that you either give up mushrooms for the
life-listing of birds, or else look into cryopreservation—you can instruct that you should be
thawed when the Agaricus list is completed.

At times it seems that our ignorance is continually increasing, to “apocryphize” some-
thing that my friend and mentor Ian Ross never actually said, but might have. Our horizons
are definitely expanding as more Agaricus biodiversity emerges, and our awareness of what we
don’t know episodically becomes more acute. Knowledge, including knowledge of gaps, ac-
cumulates. I believe I’ve gathered enough information to make a useful contribution to our gen-
eral understanding of Agaricus on this continent. Ultimately, the rationale for preparing this
edition of Agaricus of North America at this time is basic: anything can happen. I’d be mortified
if I winked out of existence without trying to put this incomplete collection of observations
in your hands, where it might just be of some use.

See if you can discover what I’ve missed.

Rick Kerrigan
Kittanning, Pennsylvania

Winter, 2015

Agaricus sipapuensis Kerrigan sp. nov.

HOLOTYPE: Specimen RMC 1272. Near Sipapu Ski Resort, Taos Co., New Mexico, USA,
26 August 2010. Leg. R. M. Chapman, deposited in SFSU herbarium.

MB 802525

Affinities
Section Bivelares subsection Hortenses; closest to A. bisporus.
Notable Features
Blunt-lapped to acute fibrillose brown scales on cap; narrow ochraceous bands may be present
below top of stem; many white fibrillose zones below ring on lower stem.
Description
PILEUS 8–11 cm diam., becoming broadly umbonate to subplane, the disc sometimes de-
pressed, margin even at maturity; pileipellis medium-dark brown, about 9E5–6E6, formed of
radially oriented hyphae, forming blunt-subimbricate to pointed appressed-fibrillose squa-
mae, except disc subentire, background whitish, not obviously discoloring; context 10–15 mm
thick, whitish to dingy, without distinct color changes when exposed, odor mild, unremark-
able. Lamellae free, close (12/cm at 1 cm from stipe), to 6 mm broad, medium pinkish-brown
after pileus expansion, later dark blackish-brown. STIPE semi-equal 5.5–7.5 cm long × 15–20
mm; surface white, generally glabrous above, or with a few narrow ochraceous bands, covered
below the annulus with many ranks of short white semierect fibrils, no color changes re-
corded; interior stuffed-hollow, the pith white, context possibly whitish but dingy toward
maturity, slightly orangish below after exposure; base unremarkable. VEILS forming a thick-
margined, supramedian, intermediate whitish annulus, flaring 5–10 mm, puffy and striate

A. sipapuensis: collection RMC 1272 [Type]. Leg. R. Chapman, above Sipapu Ski Resort, Taos Co., New
Mexico. × ~0.6. Photo courtesy of and © Robert M. Chapman.

78

A gari c u s S e c ti on B ive lare s 79

above, margin grooved to two- RWK 2263. Taos Co., New Mexico. × ~0.65.
layered, the PV smooth, pale, and
semi-entire underneath, the UV
with some indistinct brown flaps
near the stipe.

SPORES dark brown at matu-
rity, broadly ellipsoid, (6.1–) 6.6–6.8
(–7.8) × (5.1–) 5.5–5.8 (–6.5) μm,
mean = 6.7 × 5.6 μm, L/W = 1.20
(N = 60, C = 2); hilar appendix prom-
inent; apical pore not evident. BA-
SIDIA predominantly tetrasporic,
cylindro-clavate, 25–34 × 7–10.5 μm;
sterigmata 3–4 μm long. CHEILO-
CYSTIDIA about cylindrical to
broadly clavate, clumped, semicon-
tinuous, 19–25 × 6–13 μm.

Chemistry
KOH unchanging; A+A unchanging.

Habit, Habitat, Distribution
Solitary or in pairs, under Picea, very close (1–2 m) to bank of stream, ca. 2400–2500 m elev.,
Sangre de Cristo Range, New Mexico. August.

Etymology
This species was found both at and near the Sipapu Ski Resort in New Mexico, site of the
2010 NMMS Foray.

Discussion
Agaricus sipapuensis, a rare species that is not yet well known, might be taken for a member of
section Subrutilescentes; however, KOH placed on the pileipellis produces no color change.
Odor of the fresh mushrooms was mild and unremarkable. The best clue to its relationships
(in section Bivelares) comes from the annulus, which sheathes the stipe upward for only a short
distance, and terminates in a sharp boundary, thus is technically of the “intermediate” type.
The narrow ochraceous bands sometimes seen near the stipe apex (see photograph at left) are
very unusual in Agaricus.

Based on ITS DNA sequence analysis, A. sipapuensis is most closely related to A. bisporus.
Section Bivelares was thought to be reasonably well known prior to the discovery of this spe-
cies in 2010. Both of the known New Mexico collections were made within 0–2 km of the
Sipapu Lodge.

Edibility
Unknown

Agaricus cordillerensis Kerrigan sp. nov.

Holotype: Specimen RWK 1616. Banff Township, Alberta, Canada, 31  July 1990. Leg.  R.  W.
Kerrigan, deposited in SFSU herbarium.

MB 802541

Affinities
Section Sanguinolenti, subsection Sylvatici; close to A. hupohanae.
Notable Features
Somewhat slender, erect stature; brown, appressed fibrillose-squamulose cap; mildly red-staining
flesh.
Description
PILEUS ca. 5–13 cm diam., convex or broadly conic-truncate; pileipellis medium brown (ca.
6C6–6D8), often darkening in maturity (to 7F6–8F7), formed of semiradially oriented hy-
phae, forming small, appressed-pointed squamules (or these obscure, the surface approaching
innately fibrillose), except disc more entire, background whitish; context ca. 6–10 mm thick,
whitish, becoming slightly pinkish-red when exposed, odor mild to fruity-spicy. Lamellae free,
close, 4–7 mm broad, possibly obscurely marginate (paler). STIPE subequal or slightly tapered
upward, with a very slight bulb, 7–12 cm long × 12 (–20) mm above, 25 (–35) mm below; sur-
face glabrous above, with some fibrillose to scurfy velar remnants below, white, becoming
pinkish-red when incised, or (RWK 2054) the surface becoming yellowish-buff, lustrous and

A. cordillerensis: collection RWK 1616 [Type, SFSU]. Banff, Alberta. × ~0.9.

208

A gari c u s se c ti on S ang ui nole nti 209

fibrous in age); interior stuffed-hollow, con-
text whitish, slightly to moderately rufescent,
particularly at and near the apex, or (RWK
2054) pale salmon-colored throughout); base
fairly shallowly rooted. VEILS initially form-
ing a flaring, subapical to supramedian pen-
dent white annulus (no longer present in
RWK 2054), with a blunt, 1 mm thick mar-
gin fringed below with small brown UV
points, undersurface with many innate fibrils
adhering to the stipe, also with a few scurfy
to many fibrillose white velar remnants on
the lower stipe.

SPORES dark brown at maturity, ellip-
soid, (4.3–4.9–) 5.6–6.4 (–7.2–7.7) × (3.7–3.8–)
4.1–4.5 (–4.9–5.1) μm, mean = 5.9 × 4.3 μm,
L/W = 1.37 (N=120, C=4); hilar appendix
generally prominent; apical pore not evident.
BASIDIA predominantly tetrasporic, clavate,
19.5–28.5 × 6–7.5 μm; sterigmata ca. 2–2.5 μm
long. CHEILOCYSTIDIA semicylindrical
to slightly or occasionally clavate, frequently
slightly and irregularly narrower centrally,
(10–) 13.5–21 × 5–8 (–9) μm, continuous.

Chemistry
Unavailable

Habit, Habitat, Distribution
Solitary, paired, or gregarious under spruce, at high elevations in mountains of the Laramide
Belt of the Western North American Cordillera, in Colorado, New Mexico, Utah, and Al-
berta. July–August. Fairly common under mature spruce in Grand Co., Colorado.

Etymology
A species of the interior western cordillera of North America.

Discussion
Agaricus cordillerensis appears to be the most common slender brown-capped Agaricus of the Rocky
Mountains. In appearance it is something of a chameleon, as both the degree and nature of
ornamentation on the pileus surface, and the color and uniformity of surface pigmentation,
vary depending on circumstances. Older pilei can be quite dark, and specimens can be more
slender than RWK 1616, especially in deep needle litter under spruce, for example above Fraser,
Colorado, where several collections were made. The distinct ITS sequence places it in subsec-
tion Sylvatici, with several other species, close to A. hupohanae from New Mexico. Agaricus
sylvaticus (all subspecies) has a considerably different ITS sequence.

Edibility
Unknown

Agaricus sp. ‘NY 49276’

Unpublished

Affinities
‘TRc’ lineage (Zhao et al., 2011), close to A. sp. ‘ASM 13217.’
Notable Features
Moderate size and stature; brown appressed-squamulose cap; stipe surface lustrous, becoming
yellowish-reddish-brown when handled; known from New York.
B r i e f D e sc r i p t ion (provided by R. E. Halling)

“[Pileus] 3–8  cm broad, dark brown over disc, finely appressed squamulose
toward margin. Stipe bruising reddish to orangish brown, equal, 7–8 cm long,
10–12  mm broad, with ample partial veil, appearing with a slight band on
underside when still intact. Odor not phenolic, not almond. . . . KOH (- [no
reaction]). Growing on lawn near Styrax, Prunus and pine. New York Botanical
Garden, Bronx, New York. October.”
My microscopic observations: SPORES dark brown, ellipsoid (5.1–) 5.3–5.4 (–5.7–6.3) × (3.2–)
3.5–3.6 (–4.0) μm, mean size 5.4 × 3.6 μm, L/W = 1.51 (N=30, C=1); hilar appendix promi-
nent; apical pore not evident. BASIDIA clavate to broadly so, ca. 18.5–24 × 7.0–8.5 μm, ste-
rigmata ca. 2.5–3 μm long. CHEILOCYSTIDIA abundant, continuous in a deep layer, most
often broadly clavate, appearing subglobose, and potentially even catenulate, if not well sepa-
rated and seen in profile, 25–34 × 12–15.5 μm.

260

O th e r ‘ sang ui nole nt ’ L i neag e s 261

A. sp. ‘NY 49276’: collection NY 49276. Leg. (and photos courtesy of and ©) R. E. Halling. Bronx, New
York. × ~1.05.

Agaricus sp. ‘NY 49276’ has an ITS sequence that is almost identical to that of ASM 13217;
however, the microfeatures are very different, and they are separate species. They are both
related to the ‘TRc’ lineage of Zhao et al. (2011) and to at least one Australian species (‘A’ of
Lebel & Syme, 2012). NY 49276 has a fairly strong resemblance to A. rubribrunnescens as de-
scribed, and was in fact collected at the type locality. However, based on the dimensions of the
stipe, and the “slightly fibrillose” stipe character of A. rubribrunnescens, the species exemplified
by collection RWK 2005 is a closer fit to Murrill’s description. All of these species appear to
be rare and incompletely known. Edibility is unknown.

Agaricus moellerianus Bon

Psalliota campestris var. floccipes F. H. Møller, Friesia 4(1–2): 57. 1950; Agaricus. floccipes (F. H. Møller)
Bohus, Ann. Hist.-Nat. Mus. Nat. Hung. 70: 107. 1978, nom. illeg. [non A.(Hydropus) floccipes Fr., Epicr.
Syst. Mycol.: 87. 1838.]; A. moellerianus Bon, Doc. Mycol. 15(60): 6. 1985 [as nom. nov. based on A.
floccipes (F. H. Møller) Bohus].

Affinities
Section Agaricus; close to A. porphyrocephalus.

Notable Features
Moderate size, sturdy stature; broad pallid cap, becoming yellow in age or when dried; equal
stem; scant ring; short, broad spores; growing in lawns, or possibly under cypresses.

D e sc r i p t ion (from Møller 1950)
“Pileus 3–6 cm, white, turning yellow (“Straw Yellow”) when touched, of-
ten very silky and naked, when dry breaking up into thick diamond-shaped
scales. Gills rather narrow, bright red (“Vinaceous Pink”) in the expanding
stage. Stem 3–4  cm × 10–20  mm, above the weak ring densely floccose-
squamulose as in a Hebaloma species. Flesh thick, smelling of almonds. Spore
powder dark brown (“Mars Brown”) . . . Spores 6–7 × 4–5 (–6) μ. Basidia 22–
36 × 6–9 (–12) μ. In old pastures and meadows, often in quantity. September–
October.”

This species is known in North America from two collections, with good photos, made by
Gwyn Quillen at a site in Malibu, California, where it occurs regularly. Because detailed

notes on these collections are not available, I
have presented Møller’s original description
of Psalliota campestris var. floccipes. The Malibu
mushrooms are larger than what Møller knew.
Gwyn provided the following information:
Pileus diameter (3–) 8–9 (–11) cm, surface
spontaneously beginning to turn yellow within
hours of harvest; lamellae deep rosy pink when
young; stipes 3–6 cm × 20–25 mm; fruiting for
about two months after the first winter rains
(December–January). The velar remnants on
the stipe above the scant annulus were ex-
tremely obscure. The lamellae as photographed
had a pronounced “flesh” (dull pink) tone
without the “bright red” color reported by
Møller. Other descriptions will be found in
Bon (1985) and Parra (2008).

My microscopic data on GQ-1:
SPORES dark brown, broadly ellipsoid,
ranging (5.5–) 6.1–6.2 (–6.8) × (4.5–) 4.9–5.2
(–5.5) μm, mean size 6.2 × 5.1 μm, L/W = 1.22
(N = 30, C = 1); hilar appendix moderate to
An unnumbered Malibu collection. Height=72 mm. prominent; spore apex occasionally thin-
Leg. (and photo courtesy of and ©) G. Quillen. × ~1.05. walled. BASIDIA cylindro-clavate, predom-

294

A gari c u s S e c ti on A gari c u s 295

Agaricus moellerianus: specimens GQ-1. Leg. (and photo courtesy of and © ) G. Quillen, Malibu, Los Angeles
Co., California. Shown where collected. Per the collector, the mushrooms in the photo appear somewhat
tan in color, whereas to the eye they appeared white.

inantly (?) tetrasporic, 18.5–21.5 x 6–7.5 μm, sterigmata ca. 2 μm long. Cells of the lamellar
margin clavate, basidiole-like.
Chemistry
Per Parra (2008), KOH faint yellow; A+A orange, but only on the yellowed parts of the pileus
surface, while negative on the white parts.
Discussion
This mushroom grew in rings in a lawn in Malibu, on the California coast, where it occurs
with regularity. It resembles A. campestris; however, the caps become a rich yellow color in age.
The ITS DNA sequence matches those of A. moellerianus collections from France and eastern
Europe. The dimensions observed by Gwyn are similar to those Parra (2008) reported for the
species in Europe. It is a cousin of A. porphyrocephalus and a few other species on a branch at
some distance from A. campestris.

While clear photos are available, I have no comprehensive notes on any of the fresh
specimens, so a full description based on North American material is not presently possible.
The relatively small spores are distinctively broader than most others of section Agaricus (ex-
cluding the secotioid A. gastronevadensis).
Edibility
According to Gwyn Quillen, it is regularly consumed by her and her dinner guests.

Agaricus martineziensis Heinem.

Agaricus volvatus A. T. Martínez, Rev. Invest. Agr. Buenos Aires 11: 299. 1957, nom. illeg. [non A.
(Amanita) volvatus Peck, Ann. Rep. New York State Mus. 24: 59. 1872]; A. martineziensis Heinem., Bull.
Bot. Jard. Belg. 60: 339. 1990. [as nom. nov.].

Affinities
Undetermined; ITS sequence suggests a possibly basally rooted lineage, or else a sequence with
an unusual evolutionary history.
Notable Features
Young cap semispherical, brown fibrils developing into concentric zones, white margin ulti-
mately projecting; thick, elongate saccate volva surrounding much of lower stipe, cheilocys-
tidia multiseptate-filamentous.
D e sc r i p t ion (paraphrasing Martí nez [1957], Capelari et al. [2006], and
Heinemann [1990, for microdata])
PILEUS 11–20 cm diam., semispherical, becoming broadly convex and finally plane, or slightly
depressed centrally; pileipellis warm reddish-brown, “Cinnamon Brown” (of Ridgway, per
Martínez), formed of radially oriented hyphae, disaggregating into uneven concentric zones
of appressed fibrils, except disc remaining entire, background whitish, unchanging; white margin
projecting; context white, unchanging, odor weakly fungal, flavor weakly of almonds. Lamellae
free, relatively narrow, long remaining white, then chestnut color with paler margin. STIPE

A. martineziensis: collection U.C. Peixoto (SP307818). São Paulo, Brazil. × ~0.45.
Photographs courtesy of and © Marina Capelari.

494

O th e r L i neag e s N ot Y et N am e d 495

equal or slightly tapered upward, 13–15  cm
long × 15–30  mm; surface white, unchang-
ing, smooth above and fibrous-squam[ul]ose
below the annulus; interior narrowly
stuffed-hollow, context white, with light yel-
lowish grayish-brown stains mostly in the
base when sectioned; base deeply rooted,
sometimes with a grayish rhizomorph. VEILS
forming (1) a fairly stiff, flaring subapical
pendent white annulus, slightly obscurely
striate above, unadorned, margin thick, and
(2) a thick appressed to free cup-like to elon-
gate saccate volva, 4–7 cm long.

SPORES very dark brown at maturity,
“short ellipsoid,” (5.3–) 5.94 (–6.7) × (4.3–)
4.76 (–5.3) μm, mean = 5.9 × 4.8 μm; apical
pore not evident. BASIDIA tetrasporic.
CHEILOCYSTIDIA few, multiseptate,
filamentous-cylindrical, the terminal element
sometimes broader, clavate to balloon-shaped,
15–33 × 8–13 μm. Data from type.

Chemistry
KOH negative; aniline + acid on dried mate-
rial negative; H2SO4 rosy on pileus.

Habit, Habitat, Distribution
Solitary or paired on bare soil in forest or with buried wood in an enclosure for raising chick-
ens. Described from Argentina, known from Brazil, reported from Jalisco State, Mexico. Feb-
ruary, June, November, December in South America.

Discussion
Agaricus martineziensis is a very distinctive species. The volva makes this obvious, while the
multiseptate-filamentous cheilocystidia, with the terminal elements sometimes enlarged, are
also noteworthy. The chemical reactions and the ITS sequence support the idea that this south-
ern species belongs to an ancient lineage for which a sectional name has not yet been pro-
posed. Tree-building algorithms put the ITS sequence of this species on very long branches
(see also Zhao et al., 2011); either we have found no close relatives of it, or else the ITS se-
quence has evolved in an unusual way, for example, hypothetically, by saltation.

Heinemann’s paraphrase of Martínez is too abbreviated. The description of Capelari et al.
notes only the terminal elements of the cheilocystidia, but apparently refers to the same species.

I include the species in this work because Guzmán (1977) reported it from a xeric habitat
in Mexico. Per Bandala-Muñoz et al. (1988), Guzmán and García Saucedo (1973) recorded it
from Jalisco, in western central Mexico. More confirmatory information about the species in
North America should be developed.

I thank Luis Parra for providing me with several papers on this species. I would also like
to thank Marina Capelari and collaborators for their paper, photographs, and a DNA sample
from which I obtained the ITS sequence of the specimen in the previous photograph.

Edibility
Edible, but hardly delicious, per Martínez (1957).

AGARICUS
of NORTH AMERICA

Agaricus of North America is the result of 45 years of work by Richard W. Kerrigan.
This volume will serve as an authoritative yet accessible sourcebook for the specialist
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