A Trial Key to GYMNOPILUS in the Pacific Northwest
Prepared for the Pacific Northwest Key Council
by Harley Barnhart, 1994, minor revision 2005, update by Ian Gibson 2019
Copyright © Pacific Northwest Key Council 1994, 2005, 2019

TABLE OF CONTENTS
	
Introduction	1
Key to Gymnopilus	1
Systematic Arrangement of Species Included	11
Some Literature	11

INTRODUCTION

     Macroscopically, the genus Gymnopilus is characterized by usually lignicolous (saprophytic) fruiting bodies that are some shade of orange, tawny, red-brown, or yellow.  Caps are dry or, less often, moist;  never viscid.  They may or may not have a veil;  if they do, it may be fugacious, or it may leave an indistinct, or fibrillous, or membranous ring.  Spores are bright ferruginous, orange, to yellow-brown in mass.  Taste is usually bitter (terrestris and arenicola among exceptions).  Microscopically, spores are rough surfaced, from very finely to distinctly warty, sometimes with warts connected by ridges, sometimes punctate, thick walled, lacking a germ pore or a plage.  Gill edges are sterile, usually with prominent lageniform or fusiform and capitate cheilocystidia. Separated from Pholiota and other members of the Strophariaceae by the distinct spore ornamentation.  Separated from Cortinarius by having brighter spore colors, and by the sterile gill edges.  Separated from Galerina "by having the cap rarely striate, not hygrophanous and usually fleshier, and the thicker-walled spores, rather more strongly ornamented and usually lacking a hilar depression" (Orton).  Galerina spores uniformly have a plage.

     This key is an effort to sort out the Pacific Northwest species of Gymnopilus by means principally of macroscopic characters.  Descriptions are derived (and abbreviated) mainly from Hesler's 1969 monograph and from Orton's contribution to the 1993 British Fungus Flora, Vol 7.  For microscopic details (e.g. cystidia size & shape) you will have to use one of those (Hesler for most).  Incidence of species in the PNW is derived (so far) from the Hesler work, from specimens as labeled in the Univ. of Washington herbarium (WA), and from very limited collecting.  Several descriptions in Hesler, taken from Murrill or others, are incomplete.  (WA) has more collections labeled "UNIDENT" than labeled with names.

Update (2019). The taxonomy of Gymnopilus in the Pacific Northwest has so far been spared the major changes affecting other genera from molecular research. 

KEY TO GYMNOPILUS

1a	Average diameter of mature caps less than 3 cm	22
1b	Average diameter of mature caps 3 cm or more	2

2a	Cap colors yellow, buff, orange, red, brown, or some mixture thereof, without greenish or bluish tinges	6
2b	Cap essentially some color or mixture of colors as above but with tinges of bluish or greenish color, either innately or from bruising	3

3a	Cap with innate blue-green tinges (not as bruises)	4
3b	Cap without innate blue-green, but may stain or appear to stain so on bruising	5

4a	Veil lacking; stem long and slender (length up to 4x cap diam); gills adnate-sinuate or deeply emarginate; cap context when young reddish to light purplish		
		G. punctifolius

CAP 2.5-10 cm broad, convex to nearly plane, buttons lilac-vinaceous, then dull green with a bluish green bloom, or variable, green, blue, and yellow mixed (dried caps yellowish buff tinged with faded vinaceous or pale olivaceous buff). Often fibrillose and squamulose around the disc, becoming glabrous with age, dry, margin involute. Context greenish yellow, thin on margin. ODOR agreeable or not distinctive. TASTE very bitter. GILLS adnate or sinuate to deeply emarginate, yellowish olive when young, becoming more drab, dotted with yellow or ferruginous stains, finally cinnamon, broad, inserted, close to subdistant, edges often stained yellowish tawny or ferruginous. STIPE (2.5-) 10-15 cm long, 5-10 (14) mm thick,  concolorous with cap, staining brownish yellow or olive-ochre within, striate, stuffed then hollow. MICROSTRUCTURES Spores 4-4.5 (-6.5) x 3.5-4 (-5) , mostly ovoid or subovoid, -inequilateral, verruculose to somewhat asperulate, dextrinoid. Pleurocystidia and cheilocystidia. Pileus trama radial. Cuticle a repent zone of brown hyphae, bearing a turf of slender, erect, filamentous to subventricose, capitate pileocystidia. Gill trama reddish brown and hymenium dark red in KOH. Caulocystidia, flask shaped and or ventricose, commonly non-capitate, forming a turf. HABITAT gregarious to cespitose on coniferous wood, debris & rich humus, Michigan to West Coast. NOTE (WA) has many collections.

4b	Veil present (when young); stem less slender (length up to 2x cap diam); gills adnexed-adnate, at first slightly decurrent, then seceding; cap context pallid, tinged greenish or bluish green	G. aeruginosus

CAP 2-5 (rarely to 23!) cm broad, convex, dry; at first dull bluish gray green , or aeruginous to variegated green and yellow, at times with patches of salmon or livid red, becoming warm buff, pinkish buff, or at times brown or drab; fibrillose scaly, becoming rimose-areolate, each areola with 2-8 cushion-like to fibrillose scales, or sometimes squamulose without areolae, the scales tawny or blackish, margin even. Context pallid or whitish, tinged greenish, or dull bluish green, when dry becoming yellowish to vinaceous. GILLS "cream buff" to "pale ochraceous orange", lamellulae numerous, edges even to slightly rough. STIPE (3-) 5-12 cm long, (4) 10-15 (-40) mm thick, concolorous, appressed fibrillose or glabrous, dry, sometimes striate, solid becoming ± hollow, at times 3-8 connate at base, equal. VEIL arachnoid, yellowish, slight, fugacious, leaving apical evanescent zone. MICROSTRUCTURES spores 6-8.5(-9) x (3.5-)4-4.5 µ, no germ pore. Pleuro-, cheilo-, and caulocystidia. Pileus trama interwoven. HABITAT cespitose on deciduous and coniferous wood (sawdust, timber, logs, stumps). NOTES (WA) has several collections. May have oily, farinaceous odor.

5a	(3b)  Fruiting body uniformly ochraceous except for light reddish brown scales on cap (dense on disc); cap with large umbo, staining green where bruised, veil absent	G. viridans

CAP to 8 cm broad, convex, with umbo, ochraceous, becoming green spotted where bruised, dry, with conspicuous light reddish brown scales that are close together at disc and sparse otherwise. GILLS adnate, dingy brown to rust colored, broad, crowded, with undulate edges. STIPE thick (to 6 cm long x 2 cm diam), wider at base, concolorous. MICROSTRUCTURES spores (6-)7-8.5 x (4-)4.5-5 µ, not dextrinoid; cheilo- and caulocystidia; pileus trama interwoven. HABITAT cespitose on coniferous (burnt) log. NOTE A Murrill collection near Seattle, 1912; no recent record. Part of type collection in (WA)

5b	Fruiting body not uniformly colored: at first dark red to reddish brown from dense fasciculate scales, then pinkish red, yellowish red, to yellow; cap without umbo, may stain or appear to stain light grayish green where bruised	G. luteofolius

CAP 2-6(-8) cm broad, convex, obtuse, dry, when young dark red to reddish brown from dense fasciculate scales which become erect, especially at disc, then fading pinkish red or yellowish red, finally yellowish; margin fibrillose or appressed-scaly. Context at first reddish, light purplish vinaceous or lavender, fading to yellowish. GILLS adnate to uncinate or emarginate, at first yellow, then bright ferruginous, close or subdistant, edges serrate. STIPE 3-9 cm long, 3-10 mm thick, concolorous, fibrillose, equal or enlarged toward base, solid. VEIL arachnoid to submembranous, yellowish, forming a fugacious annulus. MICROSTRUCTURES spores (5.5-)6-8.5 x (3.5-)4-4.5 µ; pleuro-, cheilo-, pileo-, and caulocystidia; pileus trama interwoven. (Hesler) HABITAT cespitose to subcespitose on conifer wood, or more rarely on hardwood. NOTE Stains from bruising not in Peck's or other descriptions. A collection in 1992 from wood chips at the volunteer fire station grounds in Sutton Lake, Oregon matched Hesler's description of G. luteofolius in all respects except (1) greyish green tinges were evident on caps where they had been in contact or where handled; these colors may have been a product of the coloration in the cap context, as seen through a bruised cap; (2) pleurocystidia and caulocystidia not observed, and (3) veil whitish. The spores from this collection bore the same distinctive, random pattern of verruculose ridges indicated by Hesler (1969, fig. 3). The collection is not referrable to any other known species. Additional collections of the species were made by Kit and me same year at Cascade Head, Ore., and by Evers & Sieger at Birch Bay, WA.; latter is in (WA).

6a	(2a)  Cap without veil	7
6b	Cap with veil	11

7a	On wood	9
7b	On soil or humus	8

8a	On soil or humus; cap 3-7(-10) cm, often broadly umbonate (young); color unchanging with bruising	G. terrestris

CAP 3-7(-10) cm broad, convex to subplane, umbonate when young; amber brown, orange brown, orange, or ferruginous, somewhat paler on drying, glabrous, moist or at times subviscid; margin thin and fragile. Context watery and concolorous, fading to warm buff. ODOR and TASTE mild(!). GILLS adnate to sinuate, often seceding; ochraceous-tawny, rusty brown, to ferruginous. STIPE (4-)6-12(-14) cm long, (3-)5-10(-13) mm thick; whitish or rusty brown to ferruginous, equal or base enlarged or tapering downward, glabrous, hollow. MICROSTRUCTURES spores (5-)5.5-7 x (4-)4.5-5.5(-6) µ; ellipsoid, to subglobose or ovoid in face view, dextrinoid (wait 1 hr.); pileo- and caulocystidia only; pileus trama radial. HABITAT Michigan to West Coast. NOTE (WA) has two collections: one from N. Calif. and one from Priest Lake, Idaho, 1986.

8b	On humus; cap 1-5 cm, convex; gills and cap bruise brown	G. humicola

CAP 1-5 cm broad, convex, sometimes with wavy inrolled margin, pale orange-brown to dark reddish brown, minutely and densely squamulose, plush-like to the naked eye. Context yellowish. ODOR faint aromatic. GILLS adnate to decurrent, at first bright yellow, staining rusty or tawny where bruised, becoming yellow-ochre, eventually ferruginous. STIPE 2-9 cm long, 3-9 mm thick, pallid orange-buff to sordid-buff, staining brownish when bruised, especially at the base, appressed-fibrillose and striatulate, glabrous below scurfy apex, base often white-myceloid. MICROSTRUCTURES spores (6-)7-8.5(-9) x 4-5 µ, ellipsoid, a few subovoid; pleuro-, cheilo, pileo-, and caulocystidia. HABITAT (cespitose?); coniferous & deciduous woods, Mich., Ida., Tenn., Wash. NOTE (WA) has no collections so labeled.
 
9a	(7a)  Stipe thick and heavy (length ± 5 times diam); cheilocystia present; pleurocystidia, pileocystidia, and caulocystidia lacking	G. echinulisporus

CAP up to 7 cm broad, convex to plane, at length depressed, ± umbonate young; disc ferruginous, margin tawny (fulvous), glabrous, shining. Context not reported. GILLS sinuate-adnate with a tooth; light yellow-brown to tawny. STIPE about 6 cm long, 10-16 mm thick; whitish to concolorous with cap, striate, equal or base enlarged. MICROSTRUCTURES spores 6-8 x 5-6 µ, ellipsoid, ovoid or subglobose, verrucose, dextrinoid; cheilocystidia only, but "Cuticle of repent hyphae, at times some of the surface hyphae loosen and become semi-erect."  Stipe may also have tufts of erect hyphae. HABITAT "On wood". NOTES A Murrill species from Oregon. (WA) has one collection by Stuntz from Lake Quinault, 1971; (determ: Hesler).

9b	Stipe more slender ( length ± 10 times diam); cheilocystidia, pleurocystidia, and caulocystidia present; pileocystidia may or not be present	10

10a	Odor unremarkable; gills narrow, edges entire; pleurocystidia, cheilocystidia, and caulocystidia present	G. croceoluteus

CAP 3-8 cm broad, moist, hygrophanous, warm buff to tawny-orange, margin inrolled. GILLS adnate, decurrent by a tooth, yellow then rusty, sometimes spotted, crowded. STIPE 2-5 cm long, 2-7 mm thick at apex, pallid yellowish or orange-buff, dingy below, glabrous but fibrous-striate. MICROSTRUCTURES spores (6-5-)7-8.5(-9) x 4.5-5.5 µ, ellipsoid (sometimes broadly so), verruculose, at times conspicuously 1-guttulate; pileus trama loosely interwoven. Pleuro-, cheilo-, and caulocystidia. HABITAT on conifers, Mich., Fla., Idaho. NOTES macroscopically similar to G. liquiritiae, except for width of gills. (WA) has Stuntz collection from Mississippi.

10b	Odor mild or slightly aromatic, fragrant or of raw potatoes; gills broad, edges fimbriate; pleurocystidia (inconspicuous), cheilocystidia, pileocystidia, and caulocystidia all present	G. liquiritiae

CAP 2-8 cm broad, convex then plane or subumbonate; "gold yellow to orange foxy" (Moser), disc often with minute, brown, waxy dots; not viscid, margin even, at length striatulate. Context pale orange to tawny-yellow ("whitish to yellowish" - Guzmán) GILLS adnate, then adnexed, seceding; at first ochraceous buff, to light orange-yellow, finally ochraceous orange, to ochraceous tawny, to zinc orange, at times reddish brown spotted; edges fimbriate. STIPE (1-)3-7 cm long, (2-)3-8(-10) mm thick, pallid or dingy orange, often eccentric, apex whitish or yellowish scurfy, tapering either way, "base white tomentose" (Moser) hollow. MICROSTRUCTURES spores 7-8.5(-10) x 4-5.5 µ; pleurocystidia (inconspicuous), cheilo-, pileo-, and caulocystidia. HABITAT subcespitose on conifer. NOTES Guzmán questions pileocystidia. (WA) has no collections so labeled.

11a	(6b)  Young caps dark red to reddish brown from dense fasciculate scales; cap context at first reddish, light purple vinaceous, or lavender, fading to yellowish	
		See  G. luteofolius   (5b)
11b	Caps without dark red or purplish colors; scales, if any, yellow, orange-yellow, or tawny, and appressed; context of caps yellow or yellowish from start	12

12a	Cap medium to large (to 15 cm diam or more), with veil present when young; stipe without ring (but veil may leave evanescent zone of fibrils on stipe)	15
12b	Cap medium to very large, (to 30 cm diam or more), veil leaving membranous, submembranous, or lasting fibrillose ring on stipe	13

13a	Ring membranous, persistent, thick, margin jagged and remaining erect, fragments may cling to margin of some caps; gill attachment subsinuate; spores 7.5-9 x 4.5-5 µ	
		G. ventricosus

CAP 7-8 cm broad, convex, obtuse, reddish brown; minutely yellow fibrillose to subglabrous. Context pale yellow, unchanging. GILLS subsinuate, pale brown becoming dark cinnamon, broad and subventricose. STIPE 14-18 cm long, 20-30 mm thick, pale brownish, yellow-fibrillose to subglabrous, densely white fibrillose at apex, solid, distinctly ventricose. VEIL forming almost apical annulus. MICROSTRUCTURES spores 7.5-9 x 4-5.5 µ, ellipsoid, ovoid or alost almond shaped in face view, verruculose, no germ pore, slowly dextrinoid. Pleuro- and cheilocystidia. Pileus trama interwoven. NOTES Type (by Earle) from Stanford, Calif.; Hesler evidently saw only type. No collections so labeled in (WA).

13b	Ring membranous or submembranous,  persistent; gill attachment adnate to decurrent	14

14a	Cap usually large (8-40 [!] cm diam); stipe concolorous, often bulging below, but becoming more slender at base, sometimes "rooting" into substrate; spores (7-)8-10 x 4.5-5.5(-6) µ, ellipsoid to ovoid in face view	G. spectabilis  (= G. junonius)

CAP (5-)8-18 cm broad (Hesler), (or up to 40 cm broad - Arora!), convex, expanding to nearly plane, buff-yellow, or more rarely at first whitish, or darker yellow-orange to brown or reddish brown, silky to fibrillose, sometimes appressed fibrillose-squamulose, or nearly glabrous, at times virgate when moist, often the disc minutely squamulose, the margin even. Context at first pale yellow, then medium yellow. GILLS adnate to decurrent, at first ochraceous buff, then medium yellow; faces at times rugulose, edges fimbriate. STIPE 3-10(-20) cm long, 8-10(-30) mm thick, concolorous, often darker and brownish below, streaked fibrillose from veil, solid, hard, usually attenuated below, or may be ventricose, or the base bulbous (!). VEIL pale yellow, membranous to submembranous, ± persistent, to fibrillose, leaving a distinct annulus or an indistinct evanescent, fibrillose zone. MICROSTRUCTURES spores (7-)8-10 x 4.5-5.5(-6) µ, ellipsoid to ovoid in face view, verruculose, no germ pore. Pleurocystidia (but scattered, inconspicuous), cheilo- and caulocystidia. HABITAT cespitose; see notes following. NOTES A.H. Smith and others have observed that "spectabilis" fruits on deciduous wood, and what we have called that in the PNW on conifers is maybe G. ventricosus (Earle) Hesler, but spore dimensions on PNW "spectabilis" match those above rather than the much smaller spores of ventricosus. Orton, and others say our "spectabilis" should be called G. junonius (Fries) P.D. Orton, because taxonomic rules make spectabilis "unavailable"; Fries' original description of junonius included habit on "frondose woods," but Orton's concept is "on deciduous trees and stumps, or if apparently on the ground probably attached to buried wood; also on coniferous stumps". Assuming Orton's taxonomic point is correct, we should no doubt be using the junonius epithet for our PNW species. Many "spectabilis" collections in (WA).

14b	Cap smaller (5-8 cm diam); stipe whitish, usually equal but occasionally ventricose; spores (8.5)9-13 x (5-)6-7.5 µ, fusoid to sublimoniform in face view		
		G. subspectabilis

CAP pale yellowish tawny, closely appressed-fibrillose squamulose. Context yellowish, FeSO4 olive at gill line. GILLS adnate, deep yellow to light orange-brown,"clay color" to "tawny olive". STIPE 3.5-8 cm long, 8-14 mm thick, equal or rarely ventricose, whitish. VEIL forming a submembranous ring. MICROSTRUCTURES spores (8.5-)9-13 x (5-)6-7.5 µ, "cortinarioid" (Hesler), coarsely verrucose; pleuro-, cheilo- and caulocystidia (but note pileus cuticle has "repent hyphae, with bundles of brownish, ± erect or repent hyphae"- Hesler); pileus trama of loosely interwoven broad hyphae. HABITAT (cespitose?) on hardwood, Calif. & Mich. NOTE No collections so labeled in (WA).

15a	(12a)  Fruiting body large (cap 10-15 cm diam, stipe 7.5-10 cm long x 16-24 mm thick)	
		G. magnus

CAP 10-15 cm diam, broadly convex, pale yellow or buff, not viscid, fibrillose and ± virgate, margin becoming revolute with age. Context whitish or yellowish. GILLS adnate or slightly decurrent, "ochraceous at maturity (probably yellow when young)," often crisped and wavy toward the stipe. STIPE 7.5-10 cm long, 16-24 mm thick , concolorous, bright yellow within, equal or thicker at base, solid. VEIL arachnoid, fugacious. MICROSTRUCTURES spores 7.5-10 x 5.5-7 µ, (note approx 1.4:1 L/W aspect ratio), ellipsoid in face view, inequilateral or subamygdaliform in profile, rough-warty; cheilocystidia only; pileus trama interwoven. HABITAT cespitose, "about the base of trees", N.Y., Wash., Canada (B.C.) NOTE No collections so labeled in (WA).

15b	Fruiting body smaller (cap normally <8 cm diam, some species occasionally to 10 cm)	16

16a	Cap rusty red or dark reddish brown	17
16b	Cap yellow, ochre, golden yellow, or light reddish orange or brown, etc.	18

17a	Cap fading with age to light rusty brown on disc and ochraceous buff on margin; cap context watery olive when young; gills rusty orange where bruised; veil white	
		G. aurantiophyllus

CAP 4-8 cm broad, dark rusty red, "burnt sienna" when young, inrolled margin, expanding to plane or with slight umbo, glabrous except margin at first with slight veil fragments; in age often with minute moist darker spots. Context yellowish when old. GILLS adnexed to subdecurrent, initially buff, staining rusty orange when bruised. STIPE 6-10 cm long, 5-8(12) mm thick, equal, pallid-orange-buff, at first paler with veil fibrils; base white-myceloid with numerous white rhizomorphs. VEIL white, fugacious or leaving faint evanescent zone. MICROSTRUCTURES spores 6.5-8.5 x 4-5 µ, ellipsoid; pleuro-, cheilo-, and caulocystidia; pileus trama radial. HABITAT cespitose on sawdust. NOTES described by Hesler from one collection (by A.H. Smith) on sawdust in Grants Pass, Oregon. (WA) has no collections so labeled.

17b	Cap fading with age to orange; cap context concolorous with surface; gills not staining; veil yellowish	G. sordidostipes

CAP 4-10 cm broad, obtuse to convex, expanding to plane; rusty red, "Hay's Russet", fading to "ochraceous orange," cap minutely squamulose (lens). Context concolorous with surface. GILLS adnate to adnexed, yellowish orange. STIPE 4-10 cm long, 5-12 mm thick at apex; equal to clavate, ± concolorous with cap and darkening from base up, at first with orange-buff veil remnants. VEIL arachnoid, yellowish, leaving evanescent zone. MICROSTRUCTURES spores (5.5-)6.75 x 3.5-4.5 µ, ellipsoid, verruculose; pleuro-, cheilo, pileo-, and caulocystidia. (2 types of pileocystidia: [1] 13-24 x 5-7 µ, colorless, clavate, scattered, rare, and [2] 35-48 x 6-10 µ, clavate, brown, sometimes encrusted, often forming mounds. HABITAT cespitose on sawdust. NOTES also described by Hesler from collection by A.H. Smith, same date, same place, as G. aurantiophyllus. (WA) has no collections so labeled.

18a	(16b)  Cap "brown tomentose to fibrous-scaly on gold-yellow ground"; veil yellowish	G. sapineus

CAP (1-)3-5(-9) cm, hemispheric then plano-convex, golden yellow to tawny, paler on margin, "pale yellow-orange, pale orange, yellow, orange-brown, yellow brown, seldom reddish-brown" (Høiland). ODOR strong. GILLS adnate, "gold-yellow, damaged or old rust brown" (Moser) edges minutely fimbriate. STIPE 3-7 cm long, 4-7(-12) mm thick, glabrous, but innately fibrillose, uniformly yellowish except at base where brown when bruised, solid or stuffed, then hollow, equal or sub-attenuated downward. VEIL yellowish, scanty, sometimes remnants on cap margin, fugacious. MICROSTRUCTURES spores 7-9(-10) x 4-5.5 µ, verruculose, pleuro-, cheilo-, pileo- and caulocystidia; pileus trama radial. HABITAT subcespitose or gregarious to scattered on hard or coniferous wood or sawdust., ubiquitous U.S. and Europe. Reported from Europe on soil. NOTE (WA) has Stuntz collections Upper Snoqualmie Falls (1944) and Seattle.

18b	Cap glabrous or with minutely appressed silky fibrils; veil white, whitish, or pallid	19

19a	Stipe white or pallid entire, not staining	20 
19b	Stipe yellowish or whitish, but staining brown or developing orange, brown, rusty or tawny at base	21

20a	Gills at first yellowish, becoming rusty spotted; flesh whitish	G. penetrans

CAP 3-5 cm, glabrous, campanulate-convex then plane, fading flavescent, not viscid. ODOR none or mild. GILLS adnate to sinuate, at first pale yellowish or yellowish orange, becoming rusty spotted. STIPE 4-6 cm long, 4-7 mm thick, pallid (paler than cap), base white tomentose, equal or enlarged downwards. VEIL white or whitish, fibrillose, fugacious. MICROSTRUCTURES spores (6.5-)7-9(-9.5) x 4-5.5 µ,, verrucose; pleuro-, cheilo- and caulocystidia; pileus trama radial. HABITAT solitary or subcespitose on hard or coniferous wood, widely distributed. NOTES often synonomized with G sapineus, or considered a form thereof (Høiland considers sapineus, penetrans, hybridus all to be conspecific); note absence of pileocystidia. (WA) has one collection (by J.A.) so labeled, from Ontario, Canada.

20b	Gills not rusty spotted; flesh whitish	G. subsapineus

CAP 2-5 cm, convex, expanding, light orange-brown, "Mars Yellow". GILLS emarginate with decurrent tooth, yellowish [when young]. STIPE 4-6 cm long, 3-4 mm thick, white, silky-striate. VEIL pallid, arachnoid, fugacious, remnants on stipe. MICROSTRUCTURES spores 6-8.5 x 4.5-5 µ, ellipsoid, verruculose; pleuro- pileo-, and caulocystidia. (caulo- in distinct tufts); pileus trama radial. HABITAT (solitary or subcespitose?) on rotting wood, Ore. and Mich. NOTE (WA) has no collections so labeled.

21a	(19b)  Cap glabrous from start; odor indistinct or slightly raphanoid	G. flavidellus

CAP 2-5 cm, convex, expanding plane or slightly depressed, "ochraceous buff," melleous, "ochraceous orange," "antimony yellow" [R], margin paler, darker in age, hygrophanous. Context yellowish or pallid. ODOR not distinctive or slightly aromatic to raphanoid. GILLS adnate or sinuate with decurrent tooth, pale yellow to concolorous or ferruginous, sometimes stained or rust-spotted. STIPE 2-6 cm long, 2-6 mm thick, yellowish, usually staining brown (fulvous-brown), slightly fibrillose, equal or tapering downward, dark brown base, often white-myceloid, stuffed, then hollow. VEIL arachnoid, slight, pallid, fugacious. MICROSTRUCTURES spores 7-9 x 4-5.5 µ, verrucose to verruculose; pleuro-, cheilo-, pileo-, and caulocystidia (pileo- rare); pileus trama radial. HABITAT gregarious to subcespitose on deciduous or coniferous wood, most of temperate North America. (WA) has one specimen so labeled, from Michigan.

21b	Cap at first silky-scaly, then smooth; odor faint to strong fungoid or “subnauseous”	
		G. hybridus

CAP 2-9 cm, convex, sometimes slightly umbonate or depressed in center, pale yellow orange or orange buff, soon with yellowish ochre or yellow-orange margin, then rust or rusty-tawny from center out, minute adpressed silky-scaly at first, then ± smooth, margin at first with whitish cortinal veil remnants; context concolorous. GILLS adnate with tooth or slightly emarginate; saffron, yellowish cream or yellowish ochre, then darker, crowded, edge paler and minutely flocculose-denticulate. STIPE 22-84cm x 2-10mm, ± equal; whitish or pale cream, then then light orange brown or rusty tawny from the base up; white silky striate or fibrillose silky streaky when old. VEIL cortina-like, sometimes leaving fugacious ring zone. MICROSTRUCTURES spores 7-9 x 4-5 µ, ellipsoid, punctate rough; cheilo- and caulocystidia; pleurocystidia "rare and inconspicuous" (Orton) or "rather conspicuous" (Hesler); pileus trama distinctly interwoven (Hesler). HABITAT single or cespitose on coniferous or deciduous wood; a European species--Hesler found no U.S. specimens, but looked at Swedish collections. NOTES above description mostly from Orton; (WA) has one collection, determ. by J.A.

22a	(1a)  On soil or humus	23
22b	On wood, chips, or sawdust	25

23a	On humus	See G. humicola  (8b)
23a	On soil	24

24a	Cap and stipe medium to dark reddish brown, fading with age; stipe with grayish fibrils, with thin layer of brownish fibrils at base, and with evanescent zone at apex from veil; taste slowly bitterish	G. rufobrunneus

CAP 2-3 cm, convex expanding to plane or with a low umbo, dark reddish brown "Hays Russet" to dark rusty cinnamon, paler when old, glabrous, moist, hygrophanous; margin striate when moist. Context thin (color?). GILLS bluntly to depressed adnate, dark rusty cinnamon (when?), brighter than cap. STIPE 4-6 cm long, 2-2.5 mm thick, equal, fragile, dark rusty cinnamon all over in age, fibrils grayish, base with thin layer of brownish fibrils. VEIL leaves a faint, evanescent fibrillose zone near apex. MICROSTRUCTURES spores 7-9(-10) x 5-7 µ, ellipsoid or ovoid, verruculose; caulocystidia only. HABITAT cespitose on soil, Priest River, ID. NOTES Hesler described from one collection by A.H. Smith; (WA) has no collections so labeled.

24b	Cap light orange brown; stipe dull brown, without grayish fibrils, veil lacking; odor and taste mild	G. arenicola

CAP 1.5-3 cm, obtuse, expanding to nearly plane or broadly umbonate, surface dull, unpolished or minutely fibrillose, "tawny" or "zinc orange", evenly colored or disc finally paler and yellowish. Context pallid. ODOR and TASTE mild. GILLS adnate to slightly adnexed, orange brown, "Burnt Sienna" at maturity, 2-3 tiers of lamellulae. STIPE 2-3 cm long, 1.5-2.5 mm thick, surface dull brown, equal, solid, ± fibrillose-striate, in age dingy all over but base not appreciably darker, brownish within. MICROSTRUCTURES spores 7-8 x 3.5-4.5 µ, ellipsoid, at times subfusoid, verruculose; pleuro-, cheilo-, and caulocystidia; pileus trama radial. HABITAT Hesler described from A.H. Smith collection found on sandy soil at Longmire, Washington. NOTE (WA) has no collections so labeled.

25a	(22b)  Cap notably moist and hygrophanous, margin and disc differing	27
25b	Cap dry, ± uniform and consistent color	26

26a	Cap orange-brown to reddish brown or reddish yellow, sometimes ± entirely orange or apricot (Orton); gills narrow, adnate-seceding, bright yellow, then dull yellow to rusty, edges often staining brown; spores small (see below)	G. bellulus

CAP 1-2.5 cm, convex, obtuse becoming expanded-convex, then sometimes expanded slightly conical or slightly depressed (Watling), glabrous or minutely scurfy; margin incurved at first and sometimes exceeding gills and striate when wet; context concolorous. GILLS pale then deeper yellowish ochre or saffron, sometimes tinged sienna when old. STIPE 1.5-3 cm long, 1.5-3 mm thick, orange-saffron at first, but soon cinnamon or rusty tawny from the base up, apex usually remaining paler and when fresh pale saffron pruinose, remainder yellowish cream to pale saffron, finely silky-striate (Orton) VEIL lacking. MICROSTRUCTURES spores 3.5-5.5 x 2.6-3.5 µ, coarsely verrucose; pleuro-, cheilo-, pileo- and caulocystidia; pileus trama radial. HABITAT singly or in small groups on coniferous wood, northern U.S., Tenn., Canada, Europe. NOTES Most of this description is from Orton, who describes no pleurocystidia. Cheilocystidia small (14-26 x 3-5 µ) with long slender neck, pointed or capitate. (WA) has 3 collections so labeled.

26b Cap dark brick red; gills broad, adnexed, yellow to pale yellow-orange, not staining; spores larger (see below)	G. oregonensis

CAP 1.5-2.5 cm, conic to hemispheric convex, not fully expanding, glabrous, dark brick red , margin concolorous. GILLS adnexed, cremous darkening to rusty red. STIPE 2-3 cm long, 3-5 mm thick, concolorous or slightly paler, whitish-pulverulent throught, ±glabrescent with age, equal, hollow. VEIL lacking. MICROSTRUCTURES spores 7.5-9 x 5-5.5 µ, minutely verrucose; pleuro- and cheilocystidia only. HABITAT fir log, Oregon. NOTES Murrill collection, 1911; no record since? (WA) has no collection so labeled. Guzmán-Dávalos says spores of type are truncate with large warts.

27a	(25a)  Cap reddish brown or dull red, fading on disc first; stipe concolorous with cap near base to paler orange buff above; spores non-dextrinoid	G. rufescens

CAP 1-1.5 cm, obtuse to convex, evenly dark orange-brown "Kaiser Brown", fading to paler reddish brown and fading first on disc, glabrous, moist, hygrophanous, margin opaque, very faintly striatulate. Context concolorous. GILLS deeply adnexed to nearly free, broad, bright pinkish cream "cinnamon buff" [R], spotted orange brown in some. STIPE 2-3 cm long, 1.5-2 mm thick, concolorous with cap below but paler orange-buff above, equal, apex faintly pruinose. MICROSTRUCTURES spores 4-5.5 x 2.5-3.5 µ, ellipsoid to ovoid, verruculose; pleuro- and cheilocystidia only. HABITAT On conifer wood; Hesler described from one collection by A.H. Smith, Prairie Creek Park, Calif. NOTE (WA) has no collection so labeled.

27b	Cap reddish brown to chestnut, paler at margin; stipe umber and not concolorous with cap near base; spores dextrinoid	G. picreus? (see NOTES, below)

CAP 1-2(-5) cm, convex to campanulate-convex, then expanded, glabrous or scurfy, rarely rimulose-papillate, moist, hygrophanous, reddish brown to cinnamon, margin usually paler. GILLS adnate to decurrent, narrow, sometimes seceding, yellow to dull ochraceous or orange, then rusty red. STIPE 5-8 cm long, 2-5 mm thick, brown to reddish brown (umber), darkening with age from base up, white pulverent when young, slightly attenuated upward, base slightly enlarged, hollow, straight, glabrescent. VEIL lacking. MICROSTRUCTURES spores 7-9(-9.5) x 4.5-5.5(-6) µ, ellipsoid or subovoid in face view, verruculose, dextrinoid; pleuro-, cheilo-, pileo-, and caulocystidia; pileus trama radial; pileus and gill trama dark brown in KOH, reddish brown in Melzer's. HABITAT single or cespitose on coniferous wood, or sometimes hardwood, Northern U.S., Tenn., and Canada, also Europe. NOTES pileocystidia both scattered terminal elements and mounds; caulocystidia in tufts or palisades; Hesler described cap surface as "scurfy, disc subsquamulose" after looking at dozens of U.S. collections. Orton reports that all European authors have described surface as smooth, and he suspects Hesler described a different taxon. Other features ±agree. (WA) has one collection so labeled (by J.Ammirati).

SYSTEMATIC ARRANGEMENT OF SPECIES INCLUDED
According to Hesler

SUBGENUS   Annulati :  Veil forming a membranous to densely fibrillose, persistent annulus:

	G. spectabilis (Fr.) A.H. Smith (Syn: G. junonius  (Fr.) P.D. Orton)	14a
	G. ventricosus (Earle) Hesler	13a
	G. subspectabilis Hesler	14b

SUBGENUS   Gymnopilus:  Veil absent, or present and fugacious, not forming a persistent annulus

	Section 1: Microspori:  spores 3.5 to 7 µ long
		G. bellulus (Peck) Murrill	26a
		G. punctifolius (Peck) Singer	4a
		G. rufescens Hesler	27a
		G. sordidostipes Hesler	17b
		G. terrestris  Hesler	8a
	Section 2: Gymnopilus:  spores (6-)7-9 µ long
 		G. aeruginosus  (Peck) Singer.	4b
		G. arenicola  Hesler	24b
		G. aurantiophyllus  Hesler	17a
		G. croceoluteus Hesler	10a
		G. echinulisporus Murrill	9a
		G. flavidellus Murrill	21a
		G. humicola P.R. Harding ex Singer	8b
		G. hybridus (Fr.:Fr.) Singer	21b
		G. liquiritiae (Pers. ex Fr.) Karsten 	10b
		G. luteofolius (Peck) Singer	5b
		G. magnus (Peck) Murrill 	15a
		G. oregonensis Murrill 	26b
		G. penetrans (Fr. ex Fr.) Murrill 	20a
		G. picreus (Fr.) P. Karst. 	27b
		G. rufobrunneus Hesler	24a
		G. sapineus (Fr.) R. Maire	18a
		G. subsapineus  Hesler	20b
		G. viridans Murrill	5a

SOME LITERATURE

Guzmán-Dávalos & Guzmán.  1991.  "Additions to the Genus Gymnopilus (Agaricales, Cortinariaceae) from Mexico."  Mycotaxon 61(1): 43-56.

Guzmán-Dávalos. 2003. Type studies of Gymnopilus (Agaricales).  Mycotaxon 86: 395-423

Hesler, L.R.  1969.  North American Species of Gymnopilus. Mycological Memoir No. 3, New York Botanical Garden, Hafner Publishing Co. N.Y.  (Available from Lubrecht & Cramer).

Høiland, Klaus.  1990.  "The Genus Gymnopilus in Norway."  Mycotaxon 39: 257-279.

Orton, P.D.  1993.  "Gymnopilus."  in British Fungus Flora, 7 / Cortinariaceae p.p., by Watling and Gregory, Royal Botanic Garden, Edinburgh.