Trial Field Key to COPRINOID SPECIES in the Pacific Northwest
Section Coprinus,  Section Lanatuli and Section Atramentarii of Coprinus sensu lato
by Dr. Fred Van De Bogart 1981
New format, names in segregate genera, footnotes, and additional species 
by Ian Gibson  and Harvey Janszen 2004, revised 2007, 2017, 2023 by Ian Gibson
Copyright  1981, 2004, 2007, 2011, 2017, 2023 Pacific Northwest Key Council

TABLE OF CONTENTS
	
Coprinellus, Coprinopsis, and Parasola	3
Key to the sections of former Coprinus sensu lato	4
Coprinus sensu lato, Section Coprinus	5
Coprinus sensu lato, Section Lanatuli	8
Coprinus sensu lato, Section  Atramentarii	12
Common Coprinoid Species not included in key	13
References	15
Glossary	16
Index of Included Species	17

COPRINELLUS, COPRINOPSIS, AND PARASOLA

In 1994, molecular research by Hopple, Vilgalys, and others suggested that Coprinus comatus (the shaggy mane) and Coprinus sterquilinus were not closely related to the vast majority of Coprinus species.  This striking finding has since been confirmed by other researchers.  Since Coprinus comatus is the species on which the genus is based, the other species needed to be moved to other genera according to the rules of International Code of Botanical Nomenclature (unless a special exception was made).

In 2001, Redhead, Vilgalys, Moncalvo, Johnson, and Hopple published an article in Taxon proposing that the remaining species be disposed among three genera: Coprinellus, Coprinopsis, and Parasola. The last was a proposed new genus, but the other two names had been used previously.  The nomenclatural reasoning that the first two names were the correct ones was intricate. The story is told in less detail in Redhead's McIlvainea article (2000). These names became stabilized when a proposal to change the type of Coprinus from Coprinus comatus to Coprinus atramentarius was defeated in 2007. It should be noted however, that molecular data do not show a clear separation between Coprinellus and Psathyrella, and more changes are thus expected in future. 

Coprinopsis are primarily the shaggy scaly species, where the scales fall off easily, or species with patches, or naked species without "hymeniform" cuticles (Redhead(2000)).  They include the former Coprinus atramentarius, Coprinus cinereus and Coprinus lagopides.  Parasola includes a small group related to the former Coprinus plicatilis.  Coprinellus includes the former Coprinus micaceus and Coprinus disseminatus.  The new names are given in the Index to this key, as outlined in the Taxon article mentioned above.

Should we use these new names?  Redhead, in his 2000 McIlvainea article, answered this question. "Do we suggest that you run out and adopt these names immediately? No! Instead be conservative initially, especially in field guides." More than a decade has passed and the division of Coprinus appears to have withstood the test of time. It would seem in 2011 that it is reasonable to use the new names, but we have another problem. Many of the names used by Fred Van de Bogart have not yet been recombined into the new genera. Furthermore, his key was organized into sections of Coprinus which are no longer current. The original organization of the original key will be retained but the new names will be used where they have been changed.

Key to the sections of former Coprinus sensu lato

1a	Pileal veil elements mostly filamentous in nature (handlens), sometimes adherent, the scales, patches or layer formed seldom with any mealy character, no pileocystidia or caulocystidia present (handlens)	2

1b	Pileal veil elements mealy in nature (handlens) or lacking, never adherent, pileocystidia and caulocystidia may be present (handlens)	5

2a	Veil sometimes of a partly mealy nature but always in part filamentous, usually abundant, often adherent and masking actual surface, a cortina sometimes present when young	Section Picacei

2b	Veil elements either abundant, filamentous in nature, and loose at maturity or scanty and adherent at maturity, no mealy character present	3

3a	Veil elements sparse and adherent to the pileal surface and difficult to remove, some brown veil remnants on stipe base below a flaring annular zone		
		Section Atramentarii  p.12

3b	Veil elements mostly abundant and either loose from the first or becoming loose as pileus matures, any veil remnants on stipe base white in color	4

4a	Species with a conspicuous annulus or volva, rarely with pleurocystidia (handlens)	Section Coprinus  p.5

4b	Species with no annulus or only an annular line or fringe marking the position of the unexpanded pileal margin on the stipe base, large pleurocystidia present	
		Section Lanatuli  p.8

5a	(1b)  Pileocystidia (handlens) present generally on the entire pileal surface or occasionally restricted to a marginal fringe on the edge of the pileus	Section Setulosi

5b	Pileocystidia not present	6

6a 	Universal veil present, species medium‑small to large in size	Section Micacei

6b 	Universal veil not present, species small to medium in size	Section Hemerobi

COPRINUS, Section COPRINUS

1a	Stipe lumen without a weblike or yarnlike mass of loose hyphae inside	
		Coprinus arachnoideus

CAP 1.8-3.0 cm, acorn-shaped; creamy white and becoming pale grey‑tan; veil somewhat scanty, weblike and adherent to pileal surface. STIPE 4.0-6.5 cm x 0.22-0.36 cm, lacks the characteristic yarnlike or weblike stuffing; white, glabrous; no annulus present and the volva reduced to a few bits of fibrillose tomentum at the base. HABITAT terrestrial.

1b	Stipe lumen with a weblike or yarnlike mass of loose hyphae inside	2

2a	Species lignicolous	Coprinus alnivorus

CAP 2.0 cm, white, pale brown at apex, short acorn-shaped; veil thin and weblike with a few minute scales; at maturity only these scales persist on the blackened cap. STIPE 9.0 cm x 0.4-0.6 cm, with some loose hyphal webbing in the hollow center, surface smooth, white, glabrous; loose white membranous annulus present. GILLS large pleurocystidia present (handlens). HABITAT lignicolous.

2b		Species coprophilous or terrestrial	3

3a	Species inhabiting dry semidesert areas, not coprophilous	4

3b	Species inhabiting moister climatic areas, sometimes coprophilous	5

4a 	Pileal universal veil remnant a single stellate patch	Coprinus asterophoroides

CAP at first 2.0-3.0 cm, then 4.0-6.0 cm when mature, at first rounded then hemispherical and finally becoming campanulate, then plane; cap veil white even at maturity, very thick and feltlike, torn into a distinctive stellate patch which persists. STIPE 7.0-11.5 cm x 0.3-0.6 cm, hollow and stuffed with a distinct yarnlike strand which persists; smooth, glabrous, white at first, then blackening with maturity; volva reduced to appressed fibrils or occasional small scales on lower part of stipe; no bulbous volvate base present. HABITAT terrestrial in dry or desert areas.

4b 	Pileal universal veil remnant an irregular patch or several small patches	
			Coprinus xerophilus

CAP 1.6-4.0 cm broad, short acorn-shaped to subglobose then becoming rounded, broadly campanulate and eventually revolute, the apex remaining domelike; white at first then blackening under the veil; veil thick and feltlike, white, in one cap-like piece or in several irregular patches or areolae. STIPE 4.0-7.5 cm x 0.25-0.6 cm, hollow with a loose webbing of hyphae stuffing it or occasionally with a slender yarnlike thread in the center; stipe base bulbous with a distinct volvate ridge on its upper surface. HABITAT terrestrial in dry or desert areas.

5a	(3b)  Species coprophilous, sporocarps 1.2‑3.8 cm long prior to expansion	6

5b	Species not coprophilous, sporocarps 3.2‑25.4 cm long prior to expansion	8

6a	Stipe becoming black at apex after expansion of pileus	Coprinus spadiceisporus

CAP 3.0-3.8 cm long when young, 5.0-6.0 cm broad when mature; white when young, apex pale brown, soon entirely dark greyish brown, surface soon deeply plicate striate; pileal veil of small appressed scales, dingy or dirty white in color, loosening in age. STIPE 10.0-12.0 cm x 0.5-0.8 cm, hollow with a loose weblike mass of hyphae in it; white, smooth and glabrous except for a loose tomentum at the base, color soon darkens to light brownish over most of the length and darkens to almost black at the apex; annulus prominent, loose, white, felty in nature. HABITAT coprophilous on deer or rabbit dung.

6b	Stipe not becoming black at apex	7

7a	Stipe white at apex and pale umber at base	Coprinus umbrinus

CAP 2.5‑3.5 cm long when young, acorn-shaped, creamy yellow at margin to umber at apex becoming dark grey; surface at first with many small scales, remaining so only at the apex in maturity. STIPE 6.0-15.0 cm x 0.2-0.8 cm, hollow, stuffed with a web of loose hyphae and a yarnlike hyphal strand; white at apex, umber at base; prominent, loose, flaring, submembranous annulus present which appears to be a volva margin dislodged and carried a short distance up the stipe. HABITAT coprophilous on horse dung in open pastures.

7b	Stipe pink at apex and white at base	Coprinus roseistipitatus

CAP 2.5-3.5 cm long when young, acorn-shaped becoming revolute and somewhat laciniate, pale brown at first then white with brown apex and finally black with whitish striations; surface at first covered with a smooth universal veil which becomes scaly; those scales become evanescent and in large part disappear. STIPE 11.5 cm x 0.4-0.65 cm, hollow, stuffed with a thin webbing of hyphae; silky glabrous surface, white at base, in maturity pale pinkish grey at apex, fading to grey when dried; annulus prominent, loose, becoming black on undersurface when mature; substrate covered with a thin but persistent white feltlike mycelium. HABITAT coprophilous on rabbit or deer dung in moist hardwood forest. 

8a	(5b)  Stipe up to 50.5 cm long, sporocarps very large	Coprinus colosseus

CAP 13.0-25.4 cm long when young, smaller as lysis proceeds, oblong‑oval becoming broadly campanulate and finally laciniate‑revolute; white at first with brownish tipped scales and brown apex, entire cap darkens with maturity. STIPE 35.0-50.5 cm x 1.5-2.5 cm, hollow, with a loose yarnlike thread of hyphae inside; white at first, then darkening as autolysis proceeds; often with rhizomorphs present in the soil at the base; annulus present usually, loose, white. HABITAT and HABIT terrestrial, on loose soil in brushy deciduous forest in clumps, rare.

8b	Stipe up to 32.0 cm long, usually much shorter, sporocarps small to large	9

9a	Individual scales of pileal universal veil very small and numerous, pileus size small, 3.0‑3.2. cm long	Coprinus palmeranus

CAP 3.0-3.2 cm long, acorn-shaped, then becoming revolute; at first white with light brown apex soon becoming grey‑white with small scales of the universal veil, at maturity scales tend to become evanescent and vanish. STIPE 8.5 cm x 0.3-0.7 cm, hollow, stuffed with a loose webbing of hyphae, base bulbous with a slender subtending rhizomorph, white; annulus present, small, membranous, white. HABITAT terrestrial on clay soil in open grassy maple woods. REMARKS very similar to C. comatus but much smaller.

9b	Individual scales of pileal universal veil large and small mixed, not as numerous, pileus size larger, 4.0‑12.0 cm long	Coprinus comatus

CAP 4.0-12.0 cm long, at first ovate‑oblong, becoming campanulate and finally revolute or laciniate or both; at first white with brown tipped scales and apex, soon becoming black with dark brown scales and apex, the scales usually become somewhat evanescent and disappear in part as lysis proceeds. STIPE 7.5-19.0 cm x 0.35-2.1 cm, hollow, stuffed with a loosely interwoven yarnlike hyphal thread; base bulbous to abrupt; annulus membranous, large, loose, white, occasionally adheres to stipe base as volva. HABITAT terrestrial, widespread on lawns, roadsides, trails, compost heaps, etc.

COPRINUS Section LANATULI

1a	Species coprophilous, on compost, or on decayed straw	2

1b	Species terrestrial, lignicolous or carbonicolous	5

2a	Universal veil of cap thin, weblike and adherent at maturity, sporocarps on compost	Coprinopsis undulata

CAP at first 1.0‑3.1 cm long, becoming 1.0‑3.4 cm wide, long acorn-shaped, then campanulate, at first covered with white to pale tan universal veil, surface pale brown to hygrophanous brown at the apex, becoming dark hygrophanous grey with a brownish tint and dark brownish grey at the apex, becoming slightly plicate‑striate. STIPE 2.0‑6.0 cm x 0.15‑0.6 cm, hollow with loose hyphae in upper half of the lumen, white, surface smooth, silky and glabrous, small patches of universal veil at the base in button stages.  SPORE DEPOSIT soot black. HABIT and HABITAT on compost in large clusters. 

2b	Universal veil of cap thick, of scales that become very loose at maturity, sporocarps on dung or on wet decayed straw	3

3a	Stipe base terminating abruptly into loose mycelium at the substrate surface	
		Coprinus fimetarius

CAP at first 0.2-3.0 cm long, becoming 0.3‑2.4 cm wide, long acorn-shaped, becoming campanulate and eventually revolute; at first greyish white greyish brown with white universal veil [sic], then darkening with age but remaining brown at the apex; cap veil breaks up into loose, somewhat upturned scales. STIPE 1.5‑15.0 cm x 0.05‑0.4 cm, hollow, base often slightly enlarged and with a faint annular or volvate zone near the base; surface white, mostly smooth and glabrous. SPORE DEPOSIT soot black to deep purplish black or deep brownish black. HABITAT coprophilous or on rotting hay or straw.

3b	Stipe base terminating in a long tapering usually solid radicating process which is often inserted deeply into the substratum	4

4a	Spores 12.5‑15.4 um long	Coprinus macrorhizus var. macrorhizus

CAP at first 1.0‑3.6 cm long, becoming 1.5‑4.0 cm wide at maturity, acorn-shaped, then campanulate and eventually revolute; at first white to grey‑white with pale brown or yellow‑brown apex overlain by white universal veil, eventually dark grey to dark grey‑brown at the apex; veil breaks up into loose small scales; some plicate striation develops; surface of the cap lubricous when fresh. STIPE 6.0-23.5 cm x 0.1‑0.65 cm, up to 8.0 cm or even more of the stipe length may consist of a radicating pseudorhiza penetrating into the substrate, stipe hollow but rooting base solid with little or no lumen, base somewhat enlarged; stipe surface white, glabrous to thinly fibrillose. SPORE DEPOSIT soot black to dark brownish black. HABITAT coprophilous or on rotting hay or straw.

4b	Spores 7.5‑11.2 um long	Coprinus macrorhizus var. microsporus

As described in C. macrorhizus var. macrorhizus except that the spores are smaller (7.5-11.2 x 5.0-6.9 um) and the cap apex is yellowish.

5a	(1b)  Universal veil feltlike or thin and arachnoid (weblike), usually somewhat adherent, breaking into irregular patches	6

5b	Universal veil of parallel filaments, usually breaking up into small loose scales or somewhat adherent shredlike remnants	8

6a	Species lignicolous, universal veil white	Coprinopsis bubalina

CAP at first 1.0-3.5 cm long, becoming eventually 3.0-6.0 cm wide, rounded oblong at first, becoming campanulate then somewhat revolute; at first covered with white universal veil, but soon revealing a honey-colored, yellow‑tan to light ochre surface, apex of similar color, entire cap blackens at maturity, some plicate striation present; cap flesh buff colored. STIPE 1.5‑8.0 cm x 0.4‑1.4 cm, hollow but pithy; whitish buff and bruising tan; surface faintly pruinose, small evanescent remnants of universal veil present near the base. SPORE DEPOSIT black. HABITAT and HABIT lignicolous, on walnut and mulberry slash; solitary to clustered.

6b	Species terrestrial, universal veil pale tan to brown	7

7a	Cap apex dark greyish brown and becoming almost black at maturity, no annular line at base of stipe	Coprinopsis brunneistragulata

CAP at first 2.0-2.5 cm long, becoming 4.0-6.0 cm wide, ovate, becoming campanulate and finally revolute; at first dark gray with lighter grey universal veil patches and dark greyish brown at the apex, becoming darker grey and brownish black at the apex; some plicate striation present. STIPE 10-12 cm x 0.2-0.5 cm, hollow, base nearly abrupt; white or faintly greyish, surface somewhat fibrillose. SPORE DEPOSIT brownish black. HABITAT and HABIT terrestrial, in lawns; solitary. REMARKS Autolysis is usually incomplete.

7b	Cap apex light brown and becoming medium brown at maturity, faint annular ring present at base of stipe	Coprinopsis alutaceivelata

CAP at first 1.0-2.0 cm long, becoming 1.7-2.9 cm wide, acorn-shaped, becoming campanulate; at first tan with universal veil, apex under the veil is medium brown, at maturity cap surface is yellow-brown and apex is brown; surface eventually plicate‑striate. STIPE 1.0‑2.5cm x 0.2‑0.3 cm, hollow; faint annular or volval ring present at the base; white, surface glabrous and silky. SPORE DEPOSIT soot black. HABITAT and HABIT terrestrial, on soil and conifer needle duff; loosely clustered.

8a	(5b)  Universal veil reddish or almost black	9

8b	Universal veil. hyaline or very pallid except at cap apex	10

9a	Universal veil remnants almost black, autodigestion restricted to the gill margin, on decaying sticks	Coprinopsis marcida

CAP at first 0.4-0.5 cm long, becoming 1.0 cm wide, acorn-shaped becoming conic, then plano‑convex and finally revolute; at first pale grey or white under a dark grey to greyish black universal veil, becoming pale grey with white striae and dark grey at the apex; becomes deeply plicate‑striate STIPE 3.5 cm x 0.06‑0.11 cm, hollow but filled with water, pale grey to translucent straw color, upper surface glabrous, lower surface covered with coarse strigose grey fibrils. SPORE DEPOSIT soot black. HABITAT and HABIT lignicolous in conifer woods on moss-covered wood; solitary. REMARKS Autolysis is incomplete: only the gill margins are affected.

9b	Universal veil remnants sparse, reddish brown in color, autodigestion lyses most of the pileus, on soil mixed with brown cubical rotted wood	Coprinopsis sylvicola

CAP at first 1.5-2.0 cm long, becoming 1.8‑2.3 cm wide, long and almost cylindrical at first, becoming conic, then campanulate and finally revolute; at first medium grey and medium grey‑brown at the apex, becoming generally dark grey and dark grey‑brown at the apex; universal veil sparse, composed of minute reddish brown scales or filaments; some plicate striation present. STIPE 7.0‑9.0 cm x 0.15-0.25 cm, hollow, greyish to dirty white, surface mostly smooth, some appressed scale‑like patches on the lower one‑third. SPORE DEPOSIT soot black. HABITAT and HABIT terrestrial or sublignicolous, on leaves and debris among chunks of rotten conifer wood in a mixed forest; small loosely clustered groups.

10a	(8b)  Cap surface either with no plicate striation or with very little, on sawdust and wood chips	Coprinopsis pachyderma

CAP at first 0.8-1.1 cm long, becoming 1.8‑2.2 cm wide, acorn-shaped, becoming conic, then campanulate and finally revolute and laciniate; at first pale grey‑white and medium brown at the apex, becoming generally darker with maturity; surface faintly striate but with little development of plicate striation; universal veil loose and composed of hyaline to pale brown fibrous scaly remnants; if fresh, small glistening drops present. STIPE 6.0‑8.5 cm x 0.2‑0.3 cm, hollow, white, surface silky to slightly wooly at the apex, becoming increasingly wooly towards the base. SPORE DEPOSIT soot black. HABITAT and HABIT lignicolous on wood chips and sawdust; loose groups.

10b	Cap surface with noticeable plicate striation and often deeply so, terrestrial or lignicolous	11

11a	Autodigestion consumes only about half of each gill, the remainder either drying or petrifying, on greenhouse soil mixtures	Coprinopsis tectispora

CAP at first 1.0-1.4 cm long, becoming 1.0 as wide, long acorn-shaped, becoming conic, then campanulate and finally revolute; at first white, then grey with white veil scales and apex becoming dark grey; finely plicate‑striate; scales of the universal veil become recurved and loose at maturity. STIPE 4.0‑5.0 cm x 0.15‑0.3 cm, hollow, white, enlarged at the base and somewhat inserted into the substrate, base with annular zone of fibrils, surface minutely fibrillose. SPORE DEPOSIT deep purplish black. HABITAT and HABIT terrestrial on greenhouse soil; solitary or in loose clusters.

11b	Autodigestion of cap complete or nearly so, on soil, litter, wood or	 woody debris or on charcoal
		12

12a	Cap short acorn-shaped when young	13

12b	Cap long acorn-shaped when young	14

13a	Basidia four-spored, on soil or wood	Coprinopsis lagopides var. lagopides

CAP at first 1.5‑3.0 cm long, becoming 3.0‑5.5 cm wide, short acorn-shaped at first, becoming conic, then campanulate and finally revolute; at first pale greyish white to pale brown with concolorous apex, becoming grey to dark brownish grey and dark brownish grey to almost black at the apex; cap surface becomes plicate‑striate very early; veil soon breaks up into small loose hyaline to white scales. STIPE 8-15 cm x 0.25‑0.5 cm, hollow, white, surface glabrous or with small fragments of hyphae scattered along it or with small white to pale brown patches on or near the base. SPORE DEPOSIT dark brown to soot black. HABITAT and HABIT terrestrial to seemingly lignicolous on soil, woody debris or on rotting maple stumps; solitary or in small groups.

13b	Basidia three-spored, on burnt soil of charcoal	Coprinopsis lagopides var. trispora

As described in C. lagopides var. lagopides except that the basidia are mostly three-spored and the habitat is recently burned soil and charred debris.

14a	(12b)  Spores with normal. rounded wall in suprahilar area, no suprahilar depression present	Coprinopsis cinerea var. cinerea

CAP at first 1.5-3.5 cm long, becoming 2.0-6.0 cm wide, long acorn-shaped at first, becoming conic, then campanulate and finally campanulate and laciniate; at first white to pale brown and darker brown at apex under a white universal veil layer, becoming dark grey to grey-brown, the veil becoming very small loose scales; striate from the first and becoming deeply plicate-striate. STIPE 5.0-18.0 cm x 0.17-0.7 cm, hollow, often enlarged at the base; white; surface glabrous, sometimes with strigose wooly fibrils at the base. SPORE DEPOSIT deep brownish black to soot black. HABITAT and HABIT lignicolous to seemingly terrestrial (from buried wood ?), on soil, forest litter, wood chips, hardwood sticks, twigs, and stumps; solitary or loose clusters.

14b	Spores with a pronounced suprahilar depression	Coprinopsis cinerea var. depressa
As described for C. cinereus var. cinereus except that the spores have a conspicuous suprahilar depression.

COPRINUS Section  ATRAMENTARII

1a	Cap with prominent brownish striations, but no plicate-striations	Coprinopsis striata

CAP at first 2.0-2.8 cm long becoming 3.0-4.0 cm wide, at first ovate, then conic, then campanulate, and finally revolute, always umbonate; creamy pale tan with prominent radially oriented brown striations from apex to margin, apex brown; no plicate‑striation; no superficial evidence of a veil. STIPE 8.0‑10.0 cm x 0.24-0.55 cm, hollow, narrow at base, enlarging to maximum diameter about 1/3 of the way up, white with a few small brown scales on the lower 1/3. SPORE DEPOSIT deep brownish black. HABITAT and HABIT terrestrial, on duff in coniferous forest; solitary or in small groups.

1b	Cap with no prominent brownish striations, but sometimes with small plicate-striations	2

2a	Cap apex prominently depressed	Coprinopsis depressiceps

CAP at first 2.5.3.5 cm becoming 3.0‑4.5 cm wide, at first subglobose, then rounded conic, center of cap depressed at apex; grey‑brown to dark grey‑brown at the apex, with a few small bits of brown fibrils; no plicate‑striation. STIPE 8.0‑10.0 cm x 0.4‑0.9 cm, hollow, long and slender, tapering towards base and apex from the enlarged middle, base rooted deeply into substratum; white above the middle and white with small brown appressed scales below the middle; a small ring‑like flange present on the enlarged middle portion. SPORE DEPOSIT dark brownish black. HABITAT and HABIT terrestrial or sublignicolous, on soil around willow trees; solitary or in small clusters.

2b	Cap apex plane or umbonate	3

3a	Spores broadly ovate-ellipsoidal to subglobose	Coprinopsis pinguispora

CAP at first 3.5-4.0 cm long, becoming 3.0-4.0 cm wide, at first broadly conic-ovate, then spreading conic, never revolute; grey-brown to brown at the apex and eventually becoming entirely dark sordid brown; no plicate-striation and only a few small brown adherent fibrillose scales. STIPE 7.0-11.0 cm x 0.4-0.8 cm, hollow, broadest at a point 1/3 of the way up; white except for a few brownish adherent scales on the lower third; a narrow ring-like flange present on the enlarged portion of the stipe. SPORE DEPOSIT dark brown. HABITAT sublignicolous on clay soil at the base of alder trees.

3b	Spores ellipsoidal or narrowly ellipsoidal, never subglobose	4

4a	Cap apex rounded, flattened, or truncate, never umbonate, veil scanty	
		Coprinopsis atramentaria var. atramentaria

CAP at first 2.0-6.5 cm long, becoming 3.0-8.0 cm wide, shape variable at first, globose, subglobose, short acorn‑shaped, ovate, later becoming subconic, then broadly rounded conic and often finally revolute or laciniate, never umbonate; light grey‑tan and medium brown at apex at first, becoming darker and then blackening prior to lysis; poorly developed plicate‑striation sometimes present, surface varies from smooth and glabrous to partially covered with small brown appressed scales. STIPE 3.0-17.5 cm x  0.25‑1.0 cm, hollow, slightly enlarged about 1/3 of the way up, a ring‑like flange present on this enlarged area; white above the enlarged area and white with small brown appressed scales below it. SPORE DEPOSIT deep brownish black. HABITAT and HABIT terrestrial or sublignicolous or even lignicolous and most often found near or on well rotted wood. Solitary to densely caespitose.  REMARKS Large pleurocystidia are visible (with a handlens) between the gills.

4b	Cap apex either umbonate or veil abundant and forming areolate patches	5

5a	Cap apex umbonate, veil scanty	Coprinopsis atramentaria var. acuminata

As described in C. atramentaria var. atramentaria except that there is a prominent umbo on cap..

5b	Cap apex not umbonate, veil thick and often forming areolate patches	
		Coprinopsis atramentaria var. crassivelata

As described in C. atramentaria var. atramentaria except that the universal veil is much more abundant and breaks up into areolate patches on the cap surface

COMMON COPRINOID SPECIES NOT INCLUDED IN KEY

Dr. Van De Bogart treated only the Sections Coprinus, Lanatuli, and Atramentarii of the former Coprinus sensu lato in his key.  There are numerous other species, but the following are commonly encountered and recognizable.  Descriptions are derived from Smith(1949), Moser(1983), Arora (1986), Phillips(1991), Hansen et al.(1992), and Breitenbach & Kränzlin(1995).

Incidentally, microscopic details of the species Dr. Van De Bogart treated in his key are available in his articles from Mycotaxon given in the References, or from the CD "MatchMaker: Mushrooms of the Pacific Northwest."  The latter also contains descriptions of some other less commonly identified species of Coprinus (in the wide sense) that are not included in this key.

Coprinellus disseminatus  (Pers.: Fr.) J.E. Lange
This species has been called little helmet, fairy bonnet, or crumble cap. It is included in Section Setulosi. Features include small size, delicate consistency, pale colors when young, translucent pleated cap, failure to deliquesce, growth in crowded troops, and black spore deposit. Microscopically there are elliptic spores, cheilocystidia are rare to scattered, and the cap surface has large pileocystidia. CAP 0.5-1.0(1.5) cm across, bluntly conic becoming bell-shaped, then sometimes convex; whitish or buff with honey-brown center, becoming more grayish toward margin when old; deeply striate or pleated to center and translucent when mature, pruinose to minutely scurfy when young; flesh very thin and fragile. GILLS adnate to adnexed, readily seceding, 16-20 reaching stipe; broad; at first white but soon ash-gray, finally black or slightly paler; not deliquescing. STIPE 1.5-4 cm x 0.05-0.2 cm, thin, equal, hollow, very fragile, often curved; white or buff; with minute hairs at first, becoming smooth. HABIT and HABITAT in large dense groups (sometimes hundreds), on or near stumps or decayed wood or debris, or on buried wood, usually in woods or grassy areas. SPORE DEPOSIT dark brown to blackish. MICROSTRUCTURES spores 7-10 x 4-5 um, elliptic; basidia 4-spored, trimorphic; pleurocystidia none, cheilocystidia rare to scattered, clavate to saccate, 60-80 x 10-20 um, occasionally fusoid-ventricose and similar to pileocystidia, paraphyses 10-12 x 8-11 um; large pileocystidia 100-215 x 10-20 um with rounded apices and cylindric above a slightly ventricose base; caulocystidia more or less similar to pileocystidia and readily collapsing; clamp connections not seen. REMARKS Other species in Section Setulosi (with pileocystidia best seen at the youngest stages) occur in the Pacific Northwest. One of them, Coprinellus impatiens (now Tulosesus impatiens), is described below. According to Arora, Coprinellus impatiens differs in being slightly larger with crowded, at least somewhat deliquescent gills, and in occurring usually in smaller groups of up to twelve. 

Tulosesus impatiens  (Fr.) D. Wächt. & A. Melzer 
Features include a small orange-brown to grayish beige pleated cap which dries whitish, gills which deliquesce slowly, a whitish stipe, growth in leaf litter, and black spore deposit. Microscopically there are elliptic spores and abundant cheilocystidia and the cap surface has pileocystidia. CAP 1-4 cm across, ovoid to bluntly conic when young, becoming broadly bell-shaped or convex or remaining bluntly conic, occasionally with small obtuse umbo; hygrophanous, yellowish to dark honey-color, fading as it dries to gray-beige or whitish, becoming gray-brown to sooty in moist condition but fading to whitish; moist, pleated-striate to the disc, disc a translucent zone when fresh and moist; flesh thin, fragile. GILLS deliquescing slowly if at all, ascending adnate but readily seceding, broad, 25-31 reaching stipe; light yellowish at first, becoming blackish brown; edges whitish-fringed. STIPE 2-10 cm x 0.1-0.4 cm, equal or nearly so, hollow, fragile to moderately pliant; pallid dingy yellowish to grayish, becoming whitish when old; surface very slightly pruinose or downy or fibrillose and appearing dull to satiny. HABITAT on foliage or leaf litter, often in small groups of up to twelve. SPORE DEPOSIT black. MICROSTRUCTURES spores 8.5-11 x 5-7 um, elliptic, smooth, distinct apical pore; basidia 4-spored, trimorphic; paraphyses, 18-20 x 10-15 um, inflated, colorless, pleurocystidia none, cheilocystidia abundant, 43-68 x 10-15 um (according to Smith(1949), but Moser (1983) says between 70 and 90 um), colorless, thin-walled, fusoid-ventricose, apices acute; pileocystidia scattered, 40-100 x 9-15 um, fusoid-ventricose, colorless above ventricose part, below with the wall thickened and pale tawny in some, colorless in others; caulocystidia abundant, similar to pileocystidia except that their walls are thin and colorless throughout; clamp connections not seen.  REMARKS Coprinellus impatiens (Fr.) J.E. Lange was moved along with other species in Section Setulosi to Tulosesus as a result of molecular research. ‘Tulosesus’ is an anagram of ‘Setulosus’.

Coprinellus micaceus  (Bull.: Fr.) Vilgalys, Hopple & Jacq. Johnson
This species is sometimes called the glistening inky-cap or the mica-cap, in reference to the fine shiny mica-like particles that are appear to be sprinkled on the fresh cap. It is included in the Section Micacei. Other features include a tan to rusty-yellow striate cap, pallid gills which soon become gray or brownish, then black, slender white stipe, gregarious growth on dead wood, and dark brown to black spore deposit. Microscopically there are elliptic to miter-shaped spores, cheilocystidia and pleurocystidia. CAP 1-4cm high, 1.5-5 cm across when expanded, ovoid becoming bell-shaped, then expanding to convex; tan to yellow-brown, orange-brown, or cinnamon-brown (margin often paler), becoming grayer when old; surface sprinkled at first with minute glistening whitish particles which often disappear when old, striate at least halfway to center, margin usually split when mature; flesh thin, soft, whitish to olive-brown. GILLS adnate to adnexed or free; broad; 52-80 reaching stipe; whitish soon becoming gray or brownish, finally black, deliquescing partly or completely; edges whitish-fringed. STIPE 3-8(12) cm x 0.2-0.6 cm, equal or nearly so, fragile, hollow, white or discoloring buff; pruinose; sometimes a slight basal ring present. HABITAT in clusters on stumps, roots, rotting woody debris, or buried wood. SPORE DEPOSIT dark brown to black. MICROSTRUCTURES spores 6.5-11 x 4-6.3 um, elliptic to miter-shaped, smooth, often flattened somewhat, truncate from a central germ pore; basidia 4-spored, 22-31 x 6-10 um; pleurocystidia 70-100 x 50-70 um, vesicular to elliptic, cheilocystidia 20-90 x 20-75 um, vesicular to clavate; veil on the cap surface of spherical cells, in part brownish, encrusted or thick-walled, only occasional septa with clamps; setae on stipe apex. REMARKS The smaller Coprinellus disseminatus is somewhat similar in appearance but is translucent. Coprinopsis atramentaria is fleshier with thicker stipe, grayish cap, and gills that turn lavender-gray then black.

Coprinopsis nivea  (Pers.) Redhead, Vilgalys & Moncalvo
CAP 1.5-4cm across, 2-3.5cm high, somewhat cylindric then conic-bellshaped, later flattened with margin curved up or down; completely covered at first with snow-white, powdery to hairy-floccose veil, cap center often cream to pale ochraceous, toward margin becoming grayish and striate; flesh thin thin and membranous. GILLS free or adnexed, broad, white becoming black, edge white-fringed. STEM 5-12 cm x 0.2-0.8 cm, widening slightly downwards with base somewhat thickened, hollow, fragile, white-mealy on a whitish background. HABITAT  single or a few together; on dung of horses and cattle. SPORE DEPOSIT very dark brown to black. MICROSTRUCTURES spores 12-19.0 x 10-15 x 7.5-11 microns, lemon-shaped in face view, elliptic in side view; basidia 4-spored. basidia 4-spored, 25-40 x 12-16 microns, surrounded by 5-7(8) pseudoparaphyses; pleurocystidia abundant, 50-150 x 25-65 microns, ovoid to ellipsoid or vesiculose, cheilocystidia 30-80 x 15-50 microns, similar to pleurocystidia; veil made up of nearly spherical elements 28 to 100 microns wide; clamp connections sparse, probably just pseudoclamps REMARKS Coprinopsis nivea is characterized by the very large spores which are lemon-shaped in face view and elliptic in side view. Other features include its snow-white color due to a mealy-powdery veil (composed of spherocysts) that can be wiped off, white gills that turn black, slender white stem, and growth on cow patties and horse manure. 

Parasola plicatilis  (Curtis: Fr.) Redhead, Vilgalys & Hopple
This species is sometimes called the pleated inky-cap or Japanese parasol. It is included in the Section Hemerobi. Features include delicate pleated cap, narrow gills attached to a collar at the stipe and tending to wither rather than deliquesce, and growth on ground. Microscopically, there are elliptic to miter-shaped or lens-shaped spores, cheilocystidia and pleurocystidia. CAP 0.5-1.5 cm high, 1-3 cm across when expanded, oval or cylindric to conical when young, broadly convex or flat when old or with uplifted margin; buff to yellow-brown, usually with darker disc-shaped center, when old becoming grayish except for center; deeply grooved (pleated) nearly to center, no veil remnants; flesh very thin, fragile. GILLS free but attached to a collar around stipe top, 30-44 reaching stipe, narrow to broad; soon gray and eventually black, but tending to wither rather than liquefy. STIPE 3-7.5 cm x 0.1-0.3 cm, equal or nearly so, small bulb at base, hollow, very fragile, smooth, white or buff. HABITAT solitary, scattered or in small groups in grass, in woods, along paths etc. SPORE DEPOSIT black. MICROSTRUCTURES spores 10-13 x 6-10 um, elliptic to miter-shaped or lentiform (lens-shaped), smooth, with eccentric germ pore; basidia 4-spored, 25-40 x 11-16 um; pleurocystidia 70-125 x 20-35 um, cylindric to ventricose, cheilocystidia 35-60 x 16-25 um, lageniform to clavate or vesicular; cap cuticle of vesicular cells 25-40 x 14-25 um, some septa with clamps. REMARKS Coprinellus disseminatus is smaller, occurs in larger numbers, and is easy to distinguish microscopically. Many other Coprinoid species have cap patches or hairs.

REFERENCES

Arora, David.  1986.   Mushrooms Demystified   Second Edition.  Ten Speed Press, Berkeley.  
Breitenbach, J., Kränzlin, F.  1995.   Fungi of Switzerland  Volume 4 Agarics  Second Part. Edition Mykologia Lucerne.
Hansen, Lise, Henning Knudsen editors.  1992.  Nordic Macromycetes.  Volume 2.   Nordsvamp, Copenhagen. 
Moser, M.  1983.  Keys to Agarics and Boleti.  Translated by S. Plant.  Publisher Roger Phillips, London.
Phillips, Roger.  1991.  Mushrooms of North America.  Little, Brown, & Co., Boston.
Redhead, Scott. A., Rytas Vilgalys, Jean-Marc Moncalvo, Jacqui Johnson & John S. Hopple, Jr.  2001.  "Coprinus Pers. and the disposition of Coprinus species sensu lato".  Taxon 50: 203-241.
Redhead, Scott A. 2000. Bully for Coprinus - A story of Manure, Minutiae, and Molecules.  McIlvainea 14(2): 5-14.
Smith, A.H. 1949.  Mushrooms in Their Natural Habitats.  University of Michigan Press, Ann Arbor.
Trudell, Steve, Joe Ammirati. 2009. Mushrooms of the Pacific Northwest. Timber Press.
Uljé, C.B., C. Bas. 1991. “Studies in Coprinus II. Subsection Setulosi of section Pseudocoprinus.” Persoonia 14(3): 275-339. 
Uljé, C.B., M.E. Noordeloos. 1993. “Studies in Coprinus III. Coprinus Section Veliformes. Subdivision and revision of subsection Nivei emend.” Persoonia 15(3): 257-301. 
Van De Bogart, Fred.  1976.  "The Genus Coprinus in Western North America, Part I: Section Coprinus".  Mycotaxon 4(1): 233-275.
Van De Bogart, Fred.  1979.  "The Genus Coprinus in Western North America, Part II: Section Lanatuli".  Mycotaxon 8(1): 243-291.
Van De Bogart, Fred.  1979.  "The Genus Coprinus in Western North America, Part III: Section Atramentarii".  Mycotaxon 10(1): 155-174.
Wächter, Dieter, Andreas Melzer. 2020. Proposal for a subdivision of the family Psathyrellaceae based on a taxon-rich phylogenetic analysis with iterative multigene guide tree. Mycological Progress (2020) 19:1151–1265.

GLOSSARY

annular - resembling a ring or referring to a ring, as in an annular zone on stem
annulus - ring on stem
areola (plural areolae) - small area bounded by cracks
areolate - with a pattern like dried cracked mud
autodigestion - self-digestion
autolysis - self-digestion
caespitose - growing in close groups or close clusters or tufts (may be from a common base, but stems not joined together)
carbonicolous - growing on burned ground
clavate - like a caveman's club; when used of cystidia, implies that the part that extends outward beyond the hymenium is thicker
coprophilous - growing on dung
cuticle - the cap skin or surface layer of cells
deliquesce - melt into liquid
deliquescent - melting into a liquid
equal - of a stem, the same diameter throughout its length
evanescent - soon disappearing, fleeting
glabrous - bald, without hairs or raised fibers or scales or raised patches
globose - spherical, like a globe
hyaline - colorless
hygrophanous - surface changing color markedly as it dries, usually having a water-soaked appearance when wet and turning a lighter opaque color on drying
hymeniform - resembling a hymenium (spore-bearing surface) in form
inflated - enlarged in some part
laciniate - of cap, cut into radial bands at the margin
lageniform - of cystidia, swollen at the base with the middle and top part tapered into a long beak, like a gourd, therefore gourd-like
lignicolous - living in, on, or out of wood
lubricous - greasy or slippery or oily but not viscid (sticky) or slimy
obtuse - blunt, not pointed; greater than a right angle
paraphysis (plural paraphyses) - in Coprinus, flattened broad sterile cells between the basidia, to be distinguished from cheilocystidia and pleurocystidia which are longer in relation to their width
pileal - pertaining to the cap (pileus)
pileocystidium (plural pileocystidia) - sterile cell on the surface of the cap
pileus - cap of a mushroom
plane - having a flat surface
pleurocystidium (plural pleurocystidia) - a sterile cell located on the face (side) of a gill
pruinose - looking finely powdered or finely granular
pseudorhiza - a long rootlike extension of the lower stem
radicating - forming a root
recurved - curved back: when used of cap margin or scales means curved back upward
revolute - rolled back: when used of cap, means rolled back upward
rhizomorph - cordlike strand of twisted hyphae present around base of stem
saccate - shaped like a sac
scurfy - surface covered with branlike particles resembling scales
seceding - refers to gills that have separated in their attachment to the stem and have the appearance of being free
seta (plural setae) - pointed, elongated, thick-walled sterile cells
sordid - dingy-looking
sporocarps - fruiting bodies
stellate - star-shaped
strigose - having long stiff hairs
sub- - prefix meaning nearly, more or less, somewhat, slightly
terrestrial - appearing to grow from the ground, or on the ground, as opposed to growing on wood
tomentum - a covering of densely matted woolly hairs
trimorphic - of three forms
um - one thousandth of a millimeter, same as micron
ventricose - wider in the middle
vesicular - of cystidia, with entire cell swollen or appearing inflated like a large sac or bladder (vesicle), with only the base abruptly tapered

INDEX OF INCLUDED SPECIES
(alphabetically by species epithet)

	Coprinus alnivorus  Bogart	Sec. Coprinus - 2a	5

	Coprinopsis alutaceivelata  (Bogart) Redhead, Vilgalys & Moncalvo	
			Sec. Lanatuli - 7b	9
		synonym - Coprinus alutaceivelatus  Bogart

	Coprinus arachnoideus  Bogart	Sec. Coprinus - 1a	5

	Coprinus asterophoroides  Bogart	Sec. Coprinus - 4a	5

	Coprinopsis atramentaria  (Bull.: Fr.) Redhead, Vilgalys & Moncalvo		
			Sec. Atramentarii - 4a	12, 14
		synonym - Coprinus atramentarius  (Fr.) Fr.

	Coprinopsis atramentaria var. acuminata	Sec. Atramentarii - 5a	13

	Coprinopsis atramentaria var. crassivelata	Sec. Atramentarii - 5b	13

	Coprinopsis brunneistragulata  (Bogart) Redhead, Vilgalys & Moncalvo		
			Sec. Lanatuli - 7a	9
		synonym - Coprinus brunneistragulatus  Bogart

	Coprinopsis bubalina  (Bogart) Redhead, Vilgalys & Moncalvo		
			Sec. Lanatuli - 6a	9
		synonym - Coprinus bubalinus  Bogart

	Coprinopsis cinerea  (Schaeff.: Fr.) Redhead, Vilgalys & Moncalvo		
			Sec. Lanatuli - 14a	3, 11
		synonym - Coprinus cinereus  (Schaeff.: Fr.)  S.F.Gray

	Coprinopsis cinerea var. depressa	Sec. Lanatuli - 14b	11

	Coprinus colosseus  Bogart	Sec. Coprinus - 8a	6

	Coprinus comatus  (O.F. Müll.: Fr.) Pers.	Sec. Coprinus - 9b	3, 6

	Coprinopsis depressiceps  (Bogart) Redhead, Vilgalys & Moncalvo	
			Sec. Atramentarii - 2a	12
		synonym - Coprinus depressiceps  Bogart

	Coprinellus disseminatus  (Pers.: Fr.) J.E. Lange		3, 13, 15
		synonyms - 	Coprinus disseminatus  (Pers. ex Fr.) S.F. Gray
			Pseudocoprinus disseminatus  (Fr.) Kühner

	Coprinus fimetarius  Linn. per Fr. 	Sec. Lanatuli - 3a	8

	Tulosesus impatiens  (Fr.) D. Wächt. & A. Melzer		13
		synonyms - 	Coprinus impatiens  (Fr.) J.E. Lange
			Coprinellus impatiens  (Fr.) J.E. Lange
			Pseudocoprinus impatiens  (Fr.) Kühner

	Coprinopsis lagopides  (P. Karst.) Redhead, Vilgalys & Moncalvo	
		.	Sec. Lanatuli - 13a	3, 11
		synonym - Coprinus lagopides  P. Karst.

	Coprinopsis lagopides var. trispora  Bogart	Sec. Lanatuli - 13b	11

	Coprinopsis lagopus  (Fr.: Fr.) Redhead, Vilgalys & Moncalvo		3
		synonym - Coprinus lagopus  (Fr.) Fr.

	Coprinus macrorhizus  Pers. per Rea	Sec. Lanatuli - 4a	3, 8

	Coprinus macrorhizus var. microsporus  (Hongo) Bogart	Sec. Lanatuli - 4b	9

	Coprinopsis marcida  (Bogart) Redhead, Vilgalys & Moncalvo	
			Sec. Lanatuli - 9a	10
		synonym - Coprinus marcidus  Bogart

	Coprinellus micaceus  (Bull.: Fr.) Vilgalys, Hopple & Johnson		3, 14
		synonym - Coprinus micaceus  (Fr.) Fr.

	Coprinopsis nivea  (Pers.)		14
		synonym - 	Coprinus niveus  (Pers.) Fr.

	Coprinopsis pachyderma  (Bogart) Redhead, Vilgalys & Moncalvo		
			Sec. Lanatuli - 10a	10
		synonym - Coprinus pachydermus  Bogart

	Coprinus palmeranus  Bogart	Sec. Coprinus - 9a	6

	Coprinopsis pinguispora  (Bogart) Redhead, Vilgalys & Moncalvo 		
			Sec. Atramentarii - 3a	12
		synonym - Coprinus pinguisporus  Bogart

	Parasola plicatilis  (Curtis: Fr.) Redhead, Vilgalys & Hopple 		3, 14
		synonym - Coprinus plicatilis  (Fr.) Fr

	Coprinus roseistipitatus  Bogart	Sec. Coprinus - 7b	6

	Coprinus spadiceisporus  Bogart	Sec. Coprinus - 6a	5

	Coprinopsis striata  (Bogart) Redhead, Vilgalys & Moncalvo 	
			Sec. Atramentarii - 1a	12
		synonym - Coprinus striatus  Bogart

	Coprinopsis sylvicola  (Bogart) Redhead, Vilgalys & Moncalvo						Sec. Lanatuli - 9b	10
		synonym - Coprinus sylvicola  Bogart

	Coprinopsis tectispora  (Bogart) Redhead, Vilgalys & Moncalvo	
			Sec. Lanatuli - 11a	10
		synonym - Coprinus tectisporus  Bogart

	Coprinus umbrinus  Cke. & Massee sensu Rea	Sec. Coprinus - 7a	6

	Coprinopsis undulata  (Bogart) Redhead, Vilgalys & Moncalvo						Sec. Lanatuli - 2a	8
		synonym - Coprinus undulatus  Bogart

	Coprinus xerophilus  Bogart	Sec. Coprinus - 4b	5

- END -