Title: Trial field key to the species of HYGROPHORUS in the Pacific Northwest
Author: Ian Gibson

Notes on HEBELOMA in the Pacific Northwest
Prepared for the Pacific Northwest Key Council
By Ian Gibson, South Vancouver Island Mycological Society
Copyright © 2008, 2011, 2019, 2023 Pacific Northwest Key Council

INTRODUCTION

Considerably more field work must be done before a comprehensive key can be written for Hebeloma in the Pacific Northwest. It has been said in jest that there are only four species: veiled Hebeloma, poison pie (Hebeloma crustuliniforme), scaly-stalked Hebeloma (Hebeloma sinapizans group), and sweet-smelling Hebeloma (Hebeloma sacchariolens). That is just to illustrate the difficulty of distinguishing members of the genus which David Arora calls “another faceless and featureless collection of brownish mushrooms”.

By 2019, considerable new research on Hebeloma had been carried out by Henry Beker and his colleagues in Europe and North America including the Pacific Northwest. A European monograph was published in 2016 as the fourteenth volume of the Fungi Europaei series. A North American monograph is planned, which will advance considerably the knowledge of Pacific Northwest species.

A monograph for the veiled Hebelomas was written by A.H. Smith et al. in 1983, The veiled species of Hebeloma in the western United States. The monograph describes more than 90 species of which about a third had collections examined from the Pacific Northwest. Most of the rest were described from Colorado and could occur in the Pacific Northwest. The monograph has now been made available at MykoWeb:
http://www.mykoweb.com/systematics/literature/The%20Veiled%20Species%20of%20Hebeloma%20in%20the%20Western%20United%20States.pdf  and in somewhat less accessible form at the University of Michigan:
http://quod.lib.umich.edu/cgi/t/text/text-idx?c=fung1tc;cc=fung1tc;view=toc;idno=AAW6632.0001.001 .
The keys it contains should be consulted for detailed work. They have been abstracted below to contain only the species that Smith et al. document from the Pacific Northwest, in this case defined as British Columbia, Washington, Oregon, and Idaho. Identification is based on microscopic features.

Eberhardt et al. (2022) synonymized many of the species here, particularly with Hebeloma palustre for which they list almost two dozen synonyms from the A.H. Smith et al. (1983) monograph of veiled Hebeloma in the western United States..

Species such as Hebeloma radicosoides and Hebeloma danicum are among the ammonia fungi, studied by Naohika Sagara and found to fruit through the application of ammonia or ammonia-releasing nitrogenous material (such as rotting carcasses) to soil. Because those particular fungi have root-like extensions they have the potential to fruit in response  to underground human corpses (“corpse finders"). The occurrence of such fungi in the Pacific Northwest is not well proven.

Descriptions of the veiled species are found in the monograph mentioned above. Hebeloma crustuliniforme [group], Hebeloma sacchariolens, and the Hebeloma sinapizans group are described by Arora (1986). A North American monograph is eagerly awaited.

KEY TO SPECIES

1a	Veil present, usually fibrillose to cortinate (Subgenus Hebeloma)	2
1b	Veil absent (Subgenus Denudata)	501

2a	Spores in profile view bean-shaped to elliptic or ovate, the apex +/- rounded (Section Mesophaea)	3
2b	Spores +/- inequilateral in profile and narrowed to a blunt apex or apex +/- snoutlike (Section Hebeloma)	4

3a	Spores 10-15 um long or longer (Subsection Subviscidae)	101
3b	Spores 7-10 (11) um long (Subsection Mesophaeae)	201

4a	(2b)  Pileus white to pallid or cream color (Subsection Pallidae)	
		Hebeloma salmonense (may be a synonym of Hebeloma velutipes)
4b	Pileus more highly colored when young than in above choice	5

5a	When fresh the odor fragrant to pungent-aromatic (Subsection Praeolidae)	
		Hebeloma praeolidum
5b	Not as above (the odor if present +/- pungent to radishlike)	6

6a	Spores 7-10(11) um long (Subsection Mesosporae)	301
6b	Spores (9) 10-15 um or longer (Subsection Magnisporae)	401

101a	(3a)  Odor and taste of radish, lamellae pinkish gray, veil pallid	
		Hebeloma vinaceogriseum (synonym of H. mesophaeum var. obscurum in Eberhardt et al. 2022)
101b	Odor and taste not distinctive	102

102a	Odor and taste farinaceous, interior of stipe bay-red	
		Hebeloma sterlingii (synonymized with Hebeloma excedens in Eberhardt et al.(2022)
102b	Odor and taste not distinctive, stipe not splitting lengthwise, gregarious not caespitose	Hebeloma ollaliense

201a	(3b)  Cuticle of pileus an ixotrichodermium rarely collapsing to an ixolattice (study young pilei) (Stirps Pseudostrophosum)	202
201b	Not as above (cuticle rarely an ixolattice in age)	203

202a	Cheilocystidia 40-70 x 7-12 x 2.3-5 um	Hebeloma pseudostrophosum
202b	Cheilocystidia 28-43 x 5-7 x 7-9 um		
		Hebeloma alpinicola (may be same sp. as H. perigoense and H. nigromaculatum)

203a	(201b)  Pileus and/or gills staining dark brown to blackish on some basidiocarps in situ (Stirps Nigromaculatum)	204
203b	Not staining as above	205

204a	Veil whitish (pallid)	
		Hebeloma nigromaculatum (may be same species as H. alpinicola and H. perigoense)
204b	Veil (or at least outer layer) buff to pale tan		
		Hebeloma angelesiense (H. pseudostrophosum may be the same species)

205a	(203b)  Stipe not darkening at base in age (Stirps Pascuense)		
		Hebeloma perigoense (may be same species as H. alpinicola and H. nigromaculatum)
205b	Stipe soon darkening in basal area at least (Stirps Mesophaeum)	206

206a	Odor and/or taste raphanoid	207
206b	Odor and/or taste not as above	Hebeloma mesophaeum

207a	Spores 7-9 x 4.5-5.5 um, veil copious	Hebeloma strophosum var. strophosum
207b	Spores 8-11 x 5-6 um	208

208a	Veil copious and remains long persistent on margin of pileus and/or stipe	
		Hebeloma strophosum var. occidentale
208b	Veil thin and scarcely leaving a zone of fibrils on the stipe	
		Hebeloma mesophaeum

301a	(6a)  Stipe not darkening in lower part by maturity	302
301b	Stipe darkening (often slowly) from the base upward	304

302a	Taste bitter-farinaceous; pileus orange-brown when moist	Hebeloma aurantiellum
302b	Not as above	303

303a	Cheilocystidia 26-33 x 8-12 um	Hebeloma immutabile
303b	Cheilocystidia 40-67 x 4.5-7 um	see Hebeloma fastibile

304a	(301b)  Spores 7-9 x 4-5 um	Hebeloma olympianum
304b	Spores larger	305

305a	Odor fragrant; cheilocystidia 27-41 x 8-11 um	Hebeloma pinetorum
305b	Not as above	306

306a	Cheilocystidia 18-26 x 3-4 um, many of them tibiiform	Hebeloma subhepaticum
306b	Cheilocystidia not as above (at least wider than 3-4 um)	Hebeloma parcivelum

401a	(6b)  Stipe not staining or discoloring in the lower portion by late maturity (Stirps Coniferarum)	402
401b	Stipe soon darkening at base or lower portion, then upward	404

402a	Cheilocystidia fusoid-ventricose, the apices subcapitate; odor pungent		
		Hebeloma pungens
402b	Not as above	403

403a	Cheilocystidia (some of them) cylindric-subcapitate; pileus slimy viscid		
		Hebeloma kelloggense
403b	Not as above	Hebeloma pseudofastibile

404a	(401b)  Spores dextrinoid (medium to dark reddish brown in Melzer’s (Stirps Kuehneri)	405
404b	Spores not dextrinoid, but in a mount a few may be found which become pale to +/- reddish brown in 30 minutes; (dried specimens are most reliable for this test) (Strips Oregonense)	408

405a	Spores 9-12 um long	406
405b	Spores 10-15 um or more long	Hebeloma marginatulum

406a	Odor and taste mild or odor weakly pungent	407
406b	Odor and taste raphanoid	Hebeloma pseudofastibile

407a	Veil whitish	Hebeloma occidentale (synonymized with H. palustre in Eberhardt et al.2022)
407b	Veil grayish	Hebeloma obscurum (synonymized with H. palustre in Eberhardt et al.(2022)

408a	(404b)  Taste and usually the odor of the crushed context raphanoid	409
408b	Not as above (odor +/- pungent in some and in others the taste farinaceous to bitter or at least not raphanoid)	413

409a	Spores 9-12 um long	410
409b	Spores (10) 12-15 um long	412

410a	Spores 9-12 x 5-6.5 um	Hebeloma fastibile (may be nomen dubium et confusum)
410b	Spores 6.5-8.5 um wide	411

411a	Veil remnants on stem white	Hebeloma latisporum
411b	Veil remnants pale ochraceous	
		Hebeloma idahoense (synonymized with H. palustre in Eberhardt et al.(2022)

412a	(412b)  Spores distinctly rough under a high-dry objective		
		Hebeloma stanleyense (synonymized with H. palustre in Eberhardt et al.(2022)
412b	Spores appearing smooth under a high-dry objective or a 1.25 NA objective	
		Hebeloma oregonense

413a	(408b)  Stipe staining yellow where injured		
		Hebeloma lutescentipes (synonymized with H. palustre in Eberhardt et al.(2022)
413b	Stipe not staining yellow where handled	Hebeloma oregonense

501a	(1b)  Strong odor sweet and aromatic, like burnt sugar, caramel, fruit candy, or orange blossom	Hebeloma sacchariolens
501b	Not as above, odor often radish-like	502

502a	Stipe 1-3 cm thick, with distinct pallid to brownish flakes or protruding scales; cap 4-13(20) cm across, typically brown to cinnamon, dark reddish brown, ocher-brown, or pinkish tan, often shaded with gray or overlaid with a pallid sheen toward margin, which is at first minutely cottony, (Arora) 		
		Hebeloma sinapizans group
502b	Not as above		
Other groups including Section Denudata (H. velutipes, H. crustuliniforme group, H. cavipes, H. hiemale, etc.) 

REFERENCES

Arora, David.  1986. Mushrooms Demystified.  Ten Speed Press.
Beker, Henry J., Ursula Eberhardt, and Jan Vesterholt. 2016. Fungi Europaei Vol. 14, Hebeloma (Fr.) P. Kumm., Edizioni Technografica.
Burdsall Jr., H.H., J.S. MacFall, M.A. Albers.  1986.  “Hebeloma arenosa (Agaricales, Cortinariaceae), a new species from lake state nurseries”  Mycologia 78(5): 861-865.
Cripps, Cathy L., Ursula Eberhardt, Nicole Schütz, Henry J. Beker, Vera S. Evenson, Egon Horak. 2019. The genus Hebeloma in the Rocky Mountain Alpine Zone. MycoKeys 46: 1-54.
Eberhardt, U., Nicole Schütz, Peter Bartlett, & Henry J. Beker. 2022. 96 North American taxa sorted – Peck’s Hebeloma revisited. Mycologia 114(2):337-387.
Kauffman, C.H., A.H. Smith.  1933.  “Agarics collected in the vicinity of Rock River, Michigan in 1929” Pap. Mich. Acad. Sci. Arts Lett. 17. 1933
Sagara, Naohiko.  1984.  ‘On "Corpse Finder"’  McIlvainea 6:(2) 7-9.
Sagara, Naohiko, Takashi Yamanaka, Mark Tibbett. 2008. Chapter 4 Soil Fungi Associated with Graves and Latrines: Toward a Forensic Mycology, in ed. Mark Tibbett, David O. Carter, Soil Analysis in Forensic Taphonomy - Chemical and Biological Effects of Buried Human Remains. CRC Press. 364 pages.
Smith, Alexander H.  1938.  “New and Unusual Agarics from North America I.”  Mycologia 30: 20-41.
Smith, Alexander H.  1949 Mushrooms in Their Natural Habitats. University of Michigan Press, Ann Arbor.
Smith, Alexander H., Smith Helen V., Weber, Nancy S.  1979.  How to Know the Gilled Mushrooms.  Wm. C. Brown Company, Dubuque, Iowa.
Smith, Alexander H., V.S. Evenson, D.H. Mitchel.  1983.  The Veiled Species of Hebeloma in the Western United States.  University of Michigan Press, Ann Arbor.
Smith, Alexander H.  1984.  “Studies of Species of Hebeloma (Fr.) Kummer from the Great Lakes Region of North America I.”  Sydowia 37:271-283. 
Trudell, Steve, Joe Ammirati. 2009. Mushrooms of the Pacific Northwest. Timber Press.

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