Gymnpus sect. Vestipedes

Gymnopus section Vestipedes

Gymnopus sect. Vestipedes (Fr.) Antonín et al., Mycotaxon 63: 363. 1997.

Subtribus Vestipedes Fr., Epic. Syst. Mycol. 86. 1838.
Collybia sect. Marasmioideae Kauffman, Agar. Michigan 1: 775. 1918.
Collybia sect. Vestipedes (Fr.) Quélet, Mém. Soc. Émul. Montbéliard, sér. II, 5: 94. 1872.

Marasmius tribus Collybiae Fr., Epic. Syst. Mycol. 373. 1838.
Marasmius sect. Collybiae (Fr.) Quélet, Mém. Soc. Émul. Montbéliard sér. II, 5: 219. 1872.
Marasmius subtribus Scortei Fries, Epic. Syst. Mycol. 373. 1838.
Marasmius sect. Scortei (Fr.) Quélet, Mém. Soc. Émul. Montbéliard, sér. II, 5: 219. 1872.
Marasmius sect. Peronati Kühner, Le Botaniste 25: 85. 1933.
Collybia sect. Subfumosae Singer ex Halling, Mycologia Mem. 8: 71. 1983.
Collybia sect. Subfumosae Singer, nom. nud., Agaricales Mod. Tax. 315. 1961 (1962).

Pileus surface a layer of repent, cylindric hyphae, radially oriented, rarely with suberect end cells; hyphae sometimes diverticulate or coralloid, frequently encrusted with pigment. Stipe surface usually with a vesture, more rarely subglabrous.

Type species: Gymnopus confluens (Pers.:Fr.) Antonín, et al.

Key to Section Vestipedes
1. Spores globose . . . . Collybia subdryophila (extralimital)
1. Spores ellipsoid to lacrymoid . . . . 2

2. Spores 2-3 µm broad . . . . 2.5

2.5. Stipe base inserted on wood; lamellae forming a collar around the stipe apex . . . . G. fasciatus
2.5. Stipe arising from litter, humus, or wood but not inserted; lamellae adnexed and not fused into a collar . . . . G. striatipes

2. Spores greater than 3 µm broad . . . . 3

3. Basidiomata densely cespitose with dull, glabrous stipes . . . . G. acervatus
3. Basidiomata usually not densely cespitose; stipe pruinose, densely tomentose, pubescent or fibrous and conspicuously twisted striate . . . . 4

4. Stipe typically greater than 5 mm thick, often curved, conspicuously twisted and fibrillose striate; lamellae broad . . . . G. luxurians
4. Stipe usually not greater than 5 mm thick, usually straight and stiff, tough, densely tomentose to pruinose or pubescent; lamellae narrow, or if broad, then colored yellow and taste acrid . . . . 5

5. Taste bitter, sometimes absent; pileus dark brown, not hygrophanous, fading only slightly in color, rugulose sulcate toward the margin; lamellae subdistant to distant when drying out . . . . G. subnudus
5. Taste mild or acrid, never bitter; pileus brown to yellow brown at first, hygrophanous, even to subsulcate at margin; lamellae very crowded or distant . . . . 6

6. Taste acrid; yellow colors predominant; lamellae distant and broad . . . . G. peronatus (Oregon and Washington) IMAGE ONLY
6. Taste never acrid, mild or foetid to alliaceous; yellow colors absent; interlamellar spacing variable . . . . 7

7. Cheilocystidia present . . . . 8

8. Stipe base a tuberculate knob; cheilocystidia saccate and voluminous . . . . G. dichrous
8. Stipe base not ending in a tuberculate knob; cheilocystidia typically diverticulate, cylindric, flexuous or narrowly clavate . . . . 9

9. Stipe surface with a tawny vesture toward the base; odor and taste mild or not distinctive . . . . G. biformis
9. Stipe surface with a pallid vesture above and below; odor and taste alliaceous or not distinctive . . . . 10

10. Spores longer than 9 µm; odor and taste not distinctive . . . . 10.5

10.5. Lamellae close to subdistant . . . . G. terginus
10.5. Lamellae very crowded . . . . G. confluens

10. Spores less than 9 µm; odor and taste alliaceous . . . . 11

11. Pileus surface plicate to sulcate striate; lamellae distant; spores greater than 7 µm long; growing on wood chips . . . . G. dysodes
11. Pileus surface even or sometimes wavy at the margin, but not sulcate or plicate; lamellae crowded; spores 7 µm long or less; growing on leaf litter . . . . G. polyphyllus

7. Cheilocystidia absent . . . . 12

12. Caulocystidia very thick walled, often obscuring the cell lumen . . . . G. contrarius
12. Caulocystidia not thick walled . . . . 13

13. Spores greater than 7 µm long; odor lacking or not alliaceous . . . .14

14. Lamellae brown AND close; hyphae of pileipellis subgelatinous and arising from a narrow zone of radially oriented, conspicuously encrusted cells . . . . G. putillus
14. Lamellae white to pinkish buff, interlamellar distance variable; hyphae of pileipellis not gelatinous, encrusted cells present, scattered, inconspicuous, but not in a well-defined zone . . . . G. subterginus

13. Spores less than 7 µm long; odor alliaceous . . . .15

15. Pileus brownish red; lamellae distant . . . . G. impudicus (Wisconsin, Michigan, New York)
15. Pileus whitish; lamellae close . . . . G. hariolorum (SE USA)

Gymnopus striatipes (Pk.) Halling, Mycotaxon 63: 365. 1997. Micro features, Macro image

Marasmius striatipes Pk. Ann. Rept. N.Y. State Mus 24: 76. 1872.

Collybia cylindrospora Kauffman, Pap. Michigan Acad. Sci. 5: 126. 1925 (1926).

Pileus (3-)9-30(-50) mm broad, convex with an incurved margin when young, becoming broadly convex to nearly plane with a decurved to uplifted and even margin; surface dry, dull, glabrous, even, pale brown (clay color, cinnamon buff) when young, unchanging or fading to pale buff (light ochraceous buff, cinnamon buff, pinkish buff, pale pinkish buff, ochraceous tawny); context white, up to 5 mm thick at the disc; odor not distinctive, taste absent or slightly unpleasant to bitterish. Lamellae slightly subdecurrent to unciniate when young, soon adnate to adnexed seceding, moderately broad (3-5 mm), close when young, soon subdistant, colored white when young, darkening to buff (cartridge buff, light buff, ivory yellow) with age, concolorous with the pileus or ochraceous buff (pale ochraceous buff) when dried, edges entire. Stipe 20-60 mm long, 2-7 mm broad at apex, subclavate to clavate, often confluent at the base, fibrous and tough, white rhizoids present; surface dry, twisted striate to subsulcate, subglabrous at the apex, pubescent to tomentose or subvelutinous toward the base, colored whitish to pinkish buff (pale pinkish buff, pale pinkish cinnamon), concolorous with the pileus when dried, or drying whitish; interior hollow with age, but often with a marbled appearance when young.

Spore deposit pale cream colored. Spores 5.4-6.4(-8) x 2-2.8 µm, lacrymoid to narrowly ellipsoid to subcylindric in profile, obovoid to narrowly ellipsoid in face or back view, smooth, inamyloid, acyanophilous. Basidia 15.4-23 x 4.2-5.6 µm, clavate, four sterigmate, not siderophilous. Pleurocystidia absent. Cheilocystidia 24.5-73.5 x 2-4.2 µm, flexuous cylindric, contorted or somewhat diverticulate, thin walled, hyaline. Lamellar trama interwoven to subparallel, inamyloid; hyphae 4.2-10.8 µm in diam, smooth, thin walled. Pileus trama loosely interwoven, becoming somewhat radially arranged near the pileus surface, inamyloid; hyphae 5.4-14 µm in diam, smooth, thin walled. Pileipellis a layer of generally radially arranged, branched, repent to suberect, cylindric hyphae; cells 4.2-6.4 µm in diam, usually smooth, or only very rarely, slightly encrusted, hyaline in alkali. Stipitipellis a layer of parallel, vertically oriented hyphae; cells 3.4-5 µm in diam, smooth, thin walled, pale yellow brown in alkali, giving rise to a dense vesture of caulocystidia, 2-5(-6.4) µm in diam, thin walled, cylindric to flexuous contorted or somewhat diverticulate. Often septate and branched. Clamp connections present in all tissues.
Habit, habitat, and distribution: Gregarious to cespitose on leaf litter or rotten stumps. Occurring during August in Vermont, September and October elsewhere.
Discussion: Gymnopus striatipes is characterized by narrow spores, a pale, pubescent, sulcate-striate stipe, and rather broad, subdistant lamellae. After examining additional material from the western United States, Smith (1944) presented a slightly revised and more detailed description of G. striatipes (as C. cylindrospora) to supplement that of Kauffman (1926).

Gymnopus acervatus (Fr.) Murrill, N. Amer. Flora 9: 362. 1916. Micro features, Macro Image

Agaricus acervatus Fr., Syst. Mycol. 1: 122. 1821.
Collybia acervata (Fr.) Kummer, Führ. Pilzk. 114. 1871.
Marasmius acervatus (Fr.) Pearson & Dennis, Trans. Brit. Mycol. Soc. 31: 158. 1948.

Agaricus (Collybia) simillimus Peck, Ann. Rept. N.Y. State Mus. 24: 62. 1872.

Pileus (7-)15-45 mm broad, convex with an incurved to inrolled margin when young, expanding to plane or sometimes slightly depressed at the disc with age; margin usually opaque but sometimes translucent striate; surface dry to moist, glabrous, hygrophanous, reddish brown (bay, chestnut, mahogany red) when young, fading with age or drying to brownish (russet, hazel) on the disc and buff (pale ochraceous buff, cinnamon buff, light buff) along the margin, eventually buff nearly overall; context thin, whitish (pale ochraceous buff); odor and taste not distinctive. Lamellae adnexed to adnate, close to crowded, thin, narrow, whitish, developing pale pinkish tones (pale ochraceous salmon, pale pinkish buff) with age; edges straight and even. Stipe (15-)30-70(-80) mm long, 1.5-3(-6) mm thick, equal, fibrous but somewhat brittle; bases usually confluent; surface dry, shiny glabrous, reddish brown to brown (hessian brown, neutral red, walnut brown, kaiser brown) above, sometimes with a violet tint (dusky slate violet, mars violet), strigose to pubescent with a whitish vesture toward the base; interior hollow.

Spores white to pale cream in deposit, 5.6-6.4(-7) x 2.5-3 µm, lacrymoid to ellipsoid or slightly subreniform in profile, cylindric to ellipsoid in face or back view, smooth, inamyloid, acyanophilous. Basidia 24.5-35 x 5.6-6.4 µm, clavate, four sterigmate, not siderophilous. Pleurocystidia absent. Cheilocystidia inconspicuous, scattered, buried somewhat on the lamellar edge, 24.5-42 µm long, fusoid, irregularly clavate, less often variously lobed to diverticulate. Lamellar trama parallel to interwoven, inamyloid; hyphae 3.5-10.5 µm in diam, smooth, thin walled, hyaline or sometimes with ochraceous content in Melzer's. Pileus trama interwoven, inamyloid; hyphae 4.2-14 µm in diam, smooth, thin walled, usually hyaline, occasionally with ochraceous content in Melzer's. Pileipellis a tangled trichodermium when young, developing into a layer of repent, cylindric, branched hyphae, not diverticulate or coralloid, not radially arranged; hyphae 2-5 µm in diam, usually smooth, rarely with an encrusting brown pigment. Stipitipellis a layer of parallel, vertically oriented hyphae; cells 2.8-9.8 µm in diam, sometimes very finely encrusted, thin walled, giving rise to a vesture of tangled, multi-septate, cylindric, smooth, thin-walled caulocystidia, 2-5 µm in diam. Clamp connections present in all tissues.
Habit, habitat, and distribution: Gregarious to cespitose on decaying wood or rich humus in conifer forests or mixed woods. Appearing from July through September and occasionally in early October.
Discussion: Typically, Gymnopus acervatus is a cespitose species distinguished by its habitat on rotting wood, and by a glabrous reddish brown stipe with a whitish tomentum toward the base. In older basidiomata, the stipe color contrasts markedly with the buff color of the pileus, but in young ones, the pileus and stipe are concolorous.
The hyphal organization of the pileipellis in G. acervatus appears unique in the genus. In early stages of development, cylindric hyphae form a tangled trichodermium, but as the basidiomata mature, these hyphae apparently continue to grow and branch to form an interwoven, repent layer of cylindric cells.

Gymnopus luxurians (Pk.) Murrill, N. Amer. Flora 9: 362. 1916. Micro features, Macro Image

Collybia luxurians Peck, Bull. Torrey Bot. Club 24: 141. 1897.
Collybidium luxurians (Pk.) Murrill, Mycologia 3: 169. 1911.

Collybia compressiceps Bigelow, Rhodora 78: 124. 1976.

Pileus 10-60(-100) mm broad, convex with an inrolled to incurved margin when young, expanding to planoconvex or plane with a decurved or irregularly uplifted margin, sometimes irregularly conic if densely clustered; surface dry to moist, not hygrophanous, glabrous, even at the margin, reddish brown (chocolate, mars brown, mikado brown, kaiser brown) when young and fresh, soon fading to light brown (sayal brown, cinnamon; 57. 1. Br; 58. m. Br) toward the margin at first, eventually overall; context whitish (pale pinkish buff, pale pinkish cinnamon), thin, 3-4 mm thick at the disc; odor not distinctive, taste very slightly acrid or unpleasant. Lamellae adnate to somewhat emarginate, close to crowded, 3-4(-5) mm broad, sometimes anastomosed, pale cream buff (cartridge buff, pinkish buff; 73. p. OY); edges even at first, soon fimbriate (under a lens). Stipe 40-100(-120) mm long, (2-)5-9(-13) mm broad, equal or tapering downward, sometimes slightly enlarged at the base, tough and flexuous-fibrous, splitting easily with age; surface dry, usually twisted striate, pale buff (tilleul buff; 92. p. y. White), pale brown below, mostly covered with a fine pubescence which is easily rubbed off, cottony mycelioid at the base, rhizoids often present. Spore deposit cream colored (ivory yellow). Spores 6.4-9(-10.2) x 3.2-4.4(-5.6) µm, lacrymoid in profile, obovoid to ellipsoid in face or back view, smooth, inamyloid, acyanophilous. Basidia 18.2-27 x 5.4-7 µm, clavate, rarely two-, usually four sterigmate, not siderophilous. Cheilocystidia 21.6-43.2 µm long, clavate cylindic to broadly lobed or somewhat diverticulate. Lamellar trama parallel, inamyloid; hyphae 3.2-6.4 µm in diam, smooth walled. Pileus trama interwoven, inamyloid; hyphae 4.2-10(-16.2) µm in diam, generally smooth, rarely slightly encrusted near the pileipellis. Pileipellis a layer of radially oriented, cylindric hyphae, end cells often subclavate or fusiform and suberect; cells 2.2-7.4 µm in diam, encrusted with a brown pigment. Stipitipellis a layer of parallel, vertically oriented hyphae; cells 3.2-7.4 µm in diam, smooth and brown in KOH, giving rise to a vesture of branched, thin-walled, cylindric, septate caulocystidia, 2.2-4.2 µm in diam. Clamp connections present in all tissues.
Habit, habitat, and distribution: Gregarious, but often cespitose, rarely solitary, on rotten wood, wood chips, or on lawns (buried wood?). Occurring during June, July, August, and September.
Discussion: Peck (1897) stated that this species was imperfectly described because Underwood sent him the fungus (apparently dried) without notes. However, it is quite distinct, even in the dried state, due to the relatively large size, twisted stipe, cespitose habit, and substrate. The dark pileus colors mentioned by Bigelow (1976) seem to be restricted to very fresh or young basidiomata.

Gymnopus subnudus (Ellis ex Pk.) Halling, Mycotaxon 63: 365. 1997. Micro features, Macro images

Marasmius subnudus Ellis ex Peck, Ann. Rept. N.Y. State Mus. 51: 287. 1898.
Marasmius peronatus subnudus Ellis, N. Amer. Fungi 909. 1883.
Collybia subnuda (Ellis ex Pk.) Gilliam, Mycotaxon 4: 136. 1976.

Marasmius rubrophyllus Pennington, N. Amer. Flora 9: 271. 1915.

Pileus 10-35 mm broad, obtusely convex to broadly subumbonate with an inrolled margin when young, becoming planoconvex to plane with a decurved margin or margin uplifted and the disc depressed; surface dry, glabrous to appressed fibrillose (under a lens) with age, more or less even on the disc, soon rugulose sulcate to rugulose undulate at the margin, cinnamon brown (7E8; cinnamon brown, argus brown, brussels brown; 56. deep Br) when fresh, usually fading to cinnamon (cinnamon, vinaceous cinnamon; 6D6; near 57. 1. Br) with age or when dried out in situ; context thin, whitish, tough but quite pliable; taste bitter to mild when fresh, bitterish when dry; odor absent or not distinctive. Lamellae adnate to adnexed to nearly free around an expanded stipe apex, close to subdistant when wet or moist, usually subdistant to distant, narrow, thin at margin of pileus, moderately thick near the stipe, occasionally anastomosed, whitish when young, becoming buff to pinkish buff (buff, pinkish buff, cream buff; 5A3; 73. p. OY); edges entire or sometimes slightly pruinose (under a lens) when dry. Stipe 20-70 mm long, 1-3(-5) mm thick, straight, narrow, equal but often flared at the apex, tough and pliant; surface dry, subglabrous at the apex, whitish to grayish pubescent below, appearing glabrous when wet or water soaked, ground color concolorous with lamellae above (buff, light drab), becoming brown (6D6; 7E8) below and nearly black at the base with age; interior hollow.

Spore deposit pale yellowish white (ivory yellow; 2A2). Spores 8.6-10.8(-12) x 3.2-4.4 µm, smooth, lacrymoid to ellipsoid in profile, obovoid to ellipsoid in face or back view, inamyloid, acyanophilous. Basidia 22.8-35 x 5.6-10.8 µm, clavate to subclavate, four sterigmate, not siderophilous. Pleurocystidia absent. Cheilocystidia ventricose fusoid to somewhat mucronate or occasionally fusoid with a diverticulate apex, 29-37.8(-52.5) x 7.6-8.6 µm, thin walled, hyaline. Lamellar trama subparallel to interwoven, inamyloid; hyphae 2-7.6 µm in diam. Pileus trama interwoven, inamyloid; hyphae smooth, thin walled, 2.2-5.4 µm in diam. Pileipellis a layer of radially arranged, repent, cylindric hyphae; cells 3.2-7.6 µm in diam, not diverticulate, frequently encrusted with spiral, annular or irregular bands of brown pigment. Stipitipellis a layer of parallel, vertically oriented hyphae; cells 2.2-6.5 µm in diam, with brown pigmented walls, giving rise to long, branched and cylindric-contorted caulocystidia. Clamp connections present in all tissues.
Macrochemical reactions: PDAB--pileus and lamellar trama green.
Habit, habitat, and distribution: Scattered to gregarious on humus, leaf litter, dead twigs, and acorn involucres in mixed or deciduous woods. Appearing from July through October.
Discussion: As Gilliam (1976) indicated, Gymnopus subnudus (as Collybia) has often been misidentified in North America as Collybia urens or Collybia peronata, and stated that these latter species probably do not occur in North America. However, recent finds in Oregon and Washington by L. Norvell substantiate its occurrence on this continent. Current treatments of G. peronatus in Europe (Noordeloos, 1995) consider C. urens as a symnonym. Gymnopus subnudus has a mild or bitter taste compared to the peppery, burning taste of G. peronata. In addition, the yellow colors are lacking in G. subnuda.
In eastern North America, Gymnopus biformis is sometimes confused with G. subnudus, but they can be separated by comparing relative lamellar distances, lamellar color, color of the stipe vesture, anatomy of the pileipellis, subtrate, and, to a lesser extent, taste.
Carey and Rogerson (1977) described Hypocrea avellanea with an associated Verticillium state that often parasitizes basidiomata of G. subnudus.

Gymnopus confluens (Pers.:Fr.) Antonín et al., Mycotaxon 1997. Micro features, Macro image

Agaricus confluens Pers.:Fries, Syst. Mycol. 1: 123. 1821.
Marasmius confluens (Pers.) Ricken, Blatterp. Deutschl. 1-72 1911.
Collybia confluens (Pers.:Fr.) Kummer, Führ. Pilzk. 117. 1871.

Collybia confluens var. campanulata Peck, Bull. N.Y. State Mus. 10: 963. 1902.
Collybia confluens var. nivea Peck, Bull. N.Y. State Mus. 10: 963. 1902.

Pileus 10-35(-65) mm broad, convex with an inrolled margin when young, becoming broadly convex to campanulate to plane with a decurved to upturned margin, sometimes with a low, broad umbo; surface moist when fresh, hygrophanous, glabrous or sometimes minutely appressed fibrillose, even, colored reddish brown (7E8,7; walnut brown, rood's brown) overall when young and moist, fading to a cinnamon or clay color (5,6C5; clay color, cinnamon buff) toward the margin at first, remaining darker on the disc, eventually a pinkish buff (5A3,2; pinkish buff, light pinkish cinnamon) overall; context thin and pilant, whitish to watery buff; odor and taste mild or not distinctive, very rarely with a slight alliaceous odor. Lamellae adnate to adnexed or nearly free, sometimes forming a slight collar around the stipe apex, crowded to close, thin, narrow (0.5-1.5 mm), colored pinkish buff to pinkish cinnamon (5A2; 5B4,3; pinkish buff, pale pinkish buff, pale pinkish cinnamon) at first, becoming cream colored (3,4A3,2; cream color, warm buff, light buff) with age; edges even to fimbriate to minutely pubescent. Stipe 25-90(-130) mm long, 1.5-4(-9) mm thick, usually equal and terete, occasionally flattened and then somewhat sulcate, sometimes flared at the apex and base, pliant and tough; surface dry, colored pale cinnamon (pinkish buff, cinnamon, pale pinkish buff) below, paler above, usually minutely pubescent at first, becoming densely pubescent to strigose hispid with age or when dried in situ, sometimes subglabrous above, white mycelioid at the base; pubescence whitish buff to pale grayish; interior becoming hollow.

Spore deposit whitish to cream colored. Spores 7-9.2(-10.8) x 3.5-4.2(-5) um, slightly lacrymoid to ellipsoid or subfusoid in profile, ellipsoid in face or back view, smooth, inamyloid, acyanophilous. Basidia 22.4-26.6 x 5-7 µm, clavate, four sterigmate, not siderophilous. Pleurocystidia absent. Cheilocystidia conspicuous, 27.5-70 x 2.8-5.6 µm, irregularly clavate cylindric, flexuous contorted to strangulated, sometimes irregularly lobed or forked. Lamellar trama interwoven to parallel, inamyloid; hyphae 3.5-7.8(-14.8) ,bm in diam, smooth, thin walled, hyaline. Pileus trama loosely interwoven, inamyloid; hyphae 5.5-13.2 µm in diam, smooth, thin walled, sometimes with refractive oleiferous content. Pileipellis a poorly differentiated layer of repent, branched, radially oriented hyphae; cells 2.8-7 µm in diam, hyaline, thin walled, usually smooth, occasionally finely encrusted with a spiral to irregularly banded, pale yellowish brown pigment. Stipitipellis a layer of parallel, vertically oriented hyphae; cells 2-4.2 µm in diam, thin to moderately thick walled, giving rise to a vesture of caulocystidia, 2.8-7.8 µm in diam, smooth, thin walled, hyaline, flexuous to cylindric contorted. Clamp connections present in all tissues.
Macrochemical reactions: Guaiac--trama of pileus and lamellae blue green.
Habit, habitat, and distribution: Gregarious, but sometimes cespitose on humus, decayed leaf litter in mixed forests, conifer forests, or hardwood forests. Occurring from June through October.
Discussion: The characteristics of Gymnopus confluens are the crowded, narrow lamellae, a thin, reddish brown pileus which soon fades to a pinkish buff or whitish color, a tough stipe that is usually conspicuously pubescent and quite long and narrow in relation to the pileus diameter. In addition, this species can be cespitose in habit, and is typically odorless and marcescent in nature.
Mitchel and Smith (1978) described a Rocky Mountain form of G. confluens that has young spores which are weakly amyloid. As they point out, it is unclear whether this amyloid phenomenon is confined to Colorado populations or the species as a whole. I have not seen amyloid spores in any of the material that I have studied. In other respects, their description circumscribes a typical collection of G. confluens. Some material that I have seen was noted as having a slight alliaceous odor when fresh. This might lead to confusion with G. hariolorum or G. polyphylla, but these latter taxa have diverticulate hyphae in the pileipellis, a different aspect, and smaller spores.
Singer (1986) considered G. hariolorum to be conspecific with G. confluens, but recent works (e.g., Noordeloos, 1995) distinguish the former because of the fetid odor. At present, G. hariolorum is not known from the northeast.

Gymnopus biformis (Pk.) Halling, Mycotaxon 1997. FIGS. 64-65. 118. Micro features, Macro image

Marasmius biformis Peck, Bull. N.Y. State Mus. 67: 25. 1903.
Collybia biformis (Pk.) Singer, Sydowia 15: 55. 1962.

Marasmius longistriatus Peck, Bull. N.Y. State Mus. 105: 25. 1906.
Marasmius velutipes Berkeley & Curtis, Ann. Mag. Nat. Hist. III, 4: 294. 1859.

Pileus 10-25 mm broad, convex with an incurved and entire margin when young, becoming plane to depressed to umbilicate on the disc and rugulose sulcate on the margin; surface dry, not hygrophanous, glabrous to somewhat fibrillose, occasionally subzonate, reddish brown (8,9E8; 7,8F8,7; 59. d. Br; 56. deep Br) when young, fading to a cinnamon brown or leather brown (7D8; 6,7E7,6; sayal brown, mikado brown, snuff brown; 55. s. Br) and finally to flesh color (6C5); context whitish, thin; odor absent or mild; taste mild or not distinctive. Lamellae adnate, usually forming a collar around the stipe, close, thin, narrow to moderately broad, white to cinereous, pale pinkish buff with age or when dried; edges pubescent under a lens. Stipe 15-50 mm long, 1-4 mm thick, equal, slender and terete or rarely flattened and thickened variously, tough; surface dry, white above, tawny (6,7B8; zinc orange, orange cinnamon, cinnamon rufous) to vinaceous brown (8E8; deep livid brown) toward the base, covered with a dense pubescence which is whitish above, ochraceous to tawny (5D8,7; 6C8,7) downward, sometimes tawny only at the base, appearing subglabrous when wet; interior hollow.

Spore deposit white to cream. Spores 6.4-8.6 x 3.2-4.4 µm, lacrymoid to slightly ellipsoid in profile, obovoid in face or back view, smooth, inamyloid, acyanophilous. Basidia 19.6-28 x 4.2-5.6 µm, clavate, four sterigmate, not siderophilous. Pleurocystidia absent. Cheilocystidia 21.6-50.8 µm long, cylindric contorted to strangulated or variously lobed. Lamellar trama subparallel, inamyloid; hyphae 2.2-6.4 µm in diam, smooth, thin walled. Pileus trama inamyloid; hyphae cylindric, radially oriented, 3.2-7.5 µm in diam, smooth walled. Pileipellis a layer of repent, cylindric, radially oriented hyphae; cells encrusted with a spiral to banded pigment, 2.2-6.6 µm in diam, with diverticulate branchlets. Stipitipellis a layer of parallel, vertically oriented hyphae; cells 2.2-5.4 µm in diam, rarely with inconspicuous and scattered, irregular to spiral or plate-like yellow brown encrusting pigment, usually with yellow brown walls, giving rise to a vesture of tangled to clustered, occasionally branched, smooth caulocystidia, walls up to 1.5 µm thick. Clamp connections present in all tissues.
Macrochemical reactions: PDAB--slowly maroon on pileus trama and lamellae.
Habit, habitat, and distribution: Gregarious on soil, occasionally on leaf or needle litter, in hardwood or mixed conifer-hardwood forests. I have found it most frequently along the sides of unpaved roads, roadbanks and trails. Occurring from July into September.
Discussion: Peck (1903) indicated an affinity of G. biformis with G. subnudus. In the field, G. biformis could be mistaken for G. subnudus because of the similar pileus colors and textures of the basidiomata. However, the lamellae of G. biformis are paler, thinner, and closer than in G. subnudus, and G. biformis is mild to taste, whereas G. subnudus is usually bitter. Furthermore, G. biformis usually grows on soil and G. subnudus fruits on sticks, leaves, and humus. Gymnopus subnudus does not have a tawny pubescence on the stipe, and lacks diverticula on the pileipellis hyphae.

Gymnopus contrarius (Pk.) Halling, Mycotaxon 1997. Micro features

Marasmius contrarius Pk., Bull. N.Y. State Mus. 150: 34. 1911.
Collybia contraria (Pk.) Halling, Mycologia Mem. 8: 75. 1983.

Marasmius umbonatus Pk., Bull. Buffalo Soc. Nat. Sci. 1: 58. 1874, non Collybia umbonata Pk., Bull. Torrey Bot. Club 31: 178. 1904.

Collybia umbonatella Singer, Mycologia 35: 156. 1943.

Collybia pinastris (Kauffman) Mitchel & Smith, Mycologia 70: 1044. 1978. FIGS. 77-79.

Marasmius pinastris Kauffman, Pap. Michigan Acad. Sci. 1: 144. 1921.

Pileus 6-26 mm broad, convex with an incurved margin when young, becoming plane or depressed to umbilicate or umbonate to papillate on the disc, rugose sulcate or rugose striate on the margin, even or sometimes undulate to crenate at edge of the margin; surface dry, unpolished, glabrous to pruinose or subtomentose, colored dingy brown (snuff brown, buffy brown, hair brown) when fresh, fading to clay or ochraceous buff (clay color, light ochraceous buff; 70. 1. O Y) on the disc and yellowish buff (capucine buff; 73. p. O Y) toward the margin with age; context, thin, whitish to pale cinereous; odor slightly alliaceous, strongly of garlic or rotten cabbage; taste strongly of garlic, subastringent or none. Lamellae adnate to subdecurrent, close to subdistant, thin, narrow to moderately broad, often intervenose and forked, buff to dingy brown (cinnamon buff, (pale) buffy brown; 92. y White); edges even. Stipe 20-40 mm long, (0.5-)1-1.5(-2.5) mm thick, equal, more or less filiform, terete, tough and pliant; surface dry, subglabrous above, pubescent to tomentose or strigose toward the base, ochraceous buff (ochraceous buff; 70. 1. OY) at the apex, brown (chestnut brown, buffy brown; 55. s. Br) toward the base; interior white, solid, rarely hollow with age.

Spores (7.4-)8.6-9.8(-10.8) x 3.2-4.4 µm, lacrymoid to ellipsoid in profile, obovoid to ellipsoid in face or back view, smooth, inamyloid, acyanophilous. Basidia 15-25 x 5.8-8.2 µm, clavate, not siderophilous. Hymenial cystidia absent. Lamellar trama interwoven, inamyloid; hyphae 2.2-5.4 µm in diam, smooth, thin walled. Pileus trama interwoven, inamyloid; hyphae 4.2-10.8 µm in diam, smooth. Pileipellis a layer of radially oriented, repent, cylindric hyphae; cells 4.2-7.6 µm in diam, smooth or slightly encrusted with yellow brown pigment, with scattered diverticulate branchlets. Stipitipellis a layer of parallel, vertically oriented hyphae; cells smooth, yellow brown, moderately thick walled, giving rise to long, contorted to flexuous caulocystidia, quite thick walled (up to 3.2 µm thick), golden brown in alkali; cell lumen barely discernible. Clamp connections present in all tissues.
Habit, habitat, and distribution: Gregarious on needles of spruce and balsam fir. Appearing from June through August and during October. Known from the northeast and Colorado.
Discussion: The diagnostic features of G. contrarius include growth on needle litter, alliaceous odor and taste, and extremely thick-walled caulocystidia.
If one compares the orignal descriptions of Marasmius pinastris and M.contrarius it is obvious that they differ only in that an odor and taste are not given for the latter (Peck, 1874, 1911). Collections of a taxon (with a garlic odor) from similar habitats in Maine and adjacent Canada indicate that there is difficulty separating M. contrarius and M. pinastris. Moreover, other species (with similar odors and tastes) that appear to allow continued drying and revival in situ, often are not odoriferous if collected in the dried state.

Gymnopus dichrous (Berk. & Curt.) Halling, Mycotaxon 1997. Micro features, Macro image

Marasmius dichrous Berkeley & Curtis, Ann. Mag. Nat. Hist. II, 12: 426. 1853.
Collybia dichrous (Berk. & Curt.) Gilliam, Mycotaxon 4: 130. 1976.

Marasmius cespitosus Peck, Bull. Buffalo Soc. Nat. Sci. 1: 58. 1874.
Marasmius fagineus Morgan, J. Mycol. 11: 204. 1905.

Pileus 8-35(-40) mm broad, convex with a slightly inrolled margin when young, expanding to planoconvex with a decurved to uplifted margin, sometimes with a low umbo or shallowly depressed on the disc; surface dry, glabrous and even when young, becoming fibrillose and rugulose striate to rugulose sulcate nearly to the disc, translucent striate when water soaked, sometimes with irregular dark spots, colored dark brown to reddish brown (8E7; 46. gy. r Br) when young, fading to light reddish brown to clay (7D5; 42. 1. r Br; clay color) on the disc and margin at first, eventually overall; context thin (up to 2 mm thick), white; odor and taste mild to none. Lamellae adnate, seceding to form a collar around the stipe, thin, usually broader than thickness of context, moderately close when young, soon subdistant, intervenose and sometimes anastomosed, whitish to pale buff (light buff, pale pinkish buff), occasionally rufescent spotted; edges even. Stipe 10-50 mm long, up to 5 mm thick, enlarged at the apex, narrower in the middle, usually terete, sometimes flattened and sulcate, broadening into a tuberculate knob at the base, pliant,quite tough when dry; surface dry, concolorous with the lamellae at the apex, concolorous with the pileus or darker (olive brown) below, sometimes nearly black overall, velutinous to pubescent above, pubescent to strigose at the base; interior white, soon becoming hollow.

Spore deposit white to cream. Spores 9.8-11.8 x 3.2-4.4 µm, lacrymoid to somewhat subfusoid in profile, ellipsoid to narrowly obovoid in face or back view, smooth, inamyloid, acyanophilous. Basidia 20.5-27 x 4.2-6.6 µm, clavate to cylindric, four sterigmate, not siderophilous. Pleurocystidia absent. Cheilocystidia abundant, sometimes collapsed on lamellar edge, saccate to fusoid cylindric to variously lobed or diverticulate, 33-62 µm long. Lamellar trama parallel to interwoven, inamyloid; hyphae 4.2-10.5 µm in diam, smooth. Pileus trama interwoven, inamyloid; hyphae smooth, 3.6-8.4 µm in diam. Pileipellis a layer of typically repent, rarely branched, radially oriented hyphae; cells (2.2-)3.6-8.6(-10.8) µm in diam, encrusted with spiral to annular or irregular brown pigment, diverticulate branchlets present but infrequent, end cells often inflated and suberect. Stipitipellis a layer of parallel, vertically oriented hyphae; cells 3.2-14 µm in diam, thick walled, brown, giving rise to a vesture of obclavate, cylindric, strangulated or diverticulate caulocystidia, walls often thickened up to 2 µm. Clamp connections present in all tissues.
Habit, habitat, and distribution: Gregarious to subcespitose on hardwood logs or stumps, especially Fagus. Appearing from July to September. Pennington (1915a) reported this species from New England south to South Carolina and west to the central states. Discussion: This species can be distinguished in the field by its dark colors, pubescent stipe with a tuberculate base, and its growth on hardwood twigs, logs, and stumps, particularly those of beech. The stipe may appear to be insititious at first, but close examination will reveal a mycelium at the point of emergence from the substrate. Microscopically, the diagnostic features are the voluminous cheilocystidia, diverticulate branchlets on the hyphae of the pileipellis, and end cells which are sometimes inflated.

Gymnopus dysodes (Halling) Halling, Mycotaxon 63: 364. 1997. Micro features, Macro image

Collybia dysodes Halling, Mycologia Mem. 8: 79. 1983.

Pileus 6-60 mm broad, convex with a decurved margin, soon planoconvex to plane, occasionally more or less campanulate, with a straight or uplifted margin; surface moist, glabrous, smooth and somewhat translucent striate at first, soon conspicuously plicate to sulcate striate nearly to the disc, evenly colored dark reddish brown (walnut brown, burnt umber; near 42. 1. r Br) when young, fading with age to a cinnamon brown (cinnamon, light pinkish cinnamon; 57. 1. Br; 76. 1. y Br) on the ridges, remaining dark reddish brown in the grooves; context thin over the lamellae, 5-8 mm thick at the disc, white; odor pungent, like old onions or garlic; taste onionlike, but not too disagreeable. Lamellae adnate to adnexed, distant, moderately thin, 4-6 mm broad, light brown (fawn color; 45. 1. gy. r Br) when young, soon fading to a pale vinaceous buff (pale pinkish buff, light pinkish cinnamon, vinaceou buff; 76. 1. y Br); edges even. Stipe 15-40 mm long, 2-5 mm thick, equal or somewhat enlarged toward the base, terete to compressed, tough when young, brittle with age; surface finely pruinose overall at first, subglabrous at the apex with age, concolorous with the pileus when young, fading to a light reddish brown (army brown, vinaceous fawn; 46. gy. r Br; 42. 1. r Br) with age, eventually vinaceous buff; interior stuffed at first, hollow with age.

Spore deposit white, becoming cream colored after storage. Spores 7.8-8.4(-9) x 3.5-4.2 µm, lacrymoid to narrowly amygdaliform in profile, obovoid in face or back view, smooth, inamyloid, acyanophilous. Basidia 14-27.8 x 5.6-7 µm, clavate, four sterigmate, not siderophilous. Pleurocystidia absent. Cheilocystidia narrowly cylindric to flexuous, often diverticulate, 2-5 µm in diam. Lamellar trama interwoven, inamyloid; cells 5-10.5 µm in diam, smooth, with slightly thickened walls. Pileus trama interwoven to somewhat radial in orientation, inamyloid; hyphae 5-10.5 µm in diam, with brownish orange content in Melzer's; walls up to 2.8 µm thick. Pileipellis a layer of repent, cylindric, branched, somewhat radially oriented hyphae; cells up to 8.4 µm in diam, conspicuously encrusted with brown pigment when young; pigment less distinct and widely scattered with age; diverticulate elements present, scattered, 1.4-4.2 µm in diam. Stipitipellis a layer of parallel, vertically oriented hyphae; cells 2.8-5 µm in diam, hyaline, smooth, thin walled, giving rise to a vesture of caulocystidia, 2-7 µm in diam, smooth and thin walled. Stipe tramal hyphae hyaline, up to 15.4 µm in diam, with thick (3.5 µm) walls. Clamp connections present in all tissues.
Habit, habitat, and distribution: Gregarious to cespitose among woodchips. Voucher collections are nown from Pennsylvania, New York and Massachusetts.
Discussion: Gymnopus dysodes is characterized by the fetid odor and alliaceous taste, conspicuously plicate-sulcate pilei, diverticulate elements in the pileipellis, and a wood chip substrate. Gymnopus impudicus (Fr.) Antonín et al. seems to be most closely related. Gymnopus dysodes can be distinguished easily from G. impudicus because of larger spores (5-7.5 x 3-4 µm in G. impudicus) and the presence of cheilocystidia. In addition, Kühner and Romagnesi (1954) indicate that the pileus of G. impudicus is "...opaque ou tout au plus striolé au bord, qui est rarement un peu ridé-silloné,...." Also, G. impudicus seems to be restricted to litter and has a denser stipe vesture.

Gymnopus fasciatus (Pennington) Halling, Mycotaxon 63: 364. 1997. Micro features

Marasmius fasciatus Pennington, pro parte, N. Amer. Flora 9: 270. 1915.
Collybia fasciata (Pennington) Halling, Mycologia Mem. 8: 81. 1983.

Marasmius anomalus Peck, Ann. Rept. N.Y. State Mus. 24: 76. 1872, non M. anomalus Lasch ex Rabenhorst, Klotzchii Herb. Vivum 1806. 1854.

The following description of macroscopic features is from Peck (1872):
"Pileus thin, convex, smooth, reddish-gray; lamellae close, narrow, rounded behind and united with each other, free, whitish or pallid; stem equal, hollow, smooth or slightly pruinose, pallid, reddish brown at the base. Plant 1'-2' high, pileus .5'-1' broad, stem 1" thick. Sticks among leaves in woods. Catskill. July."

Spores (5.4-)7.4-9.6 x 2.2-3.2 µm, narrowly ellipsoid to lacrymoid to slightly reniform in profile, obovoid in face or back view, smooth, inamyloid, acyanophilous. Basidia 21-25 x 4.2-6.8 µm, two or four sterigmate, clavate, not siderophilous. Hymenial cystidia apparently absent. Lamellar trama interwoven or subparallel, inamyloid; hyphae collapsed, smooth. Pileus trama interwoven, inamyloid; hyphae 3.5-14 µm in diam, slightly collapsed, smooth, thin walled. Pileipellis a layer of repent, branched, somewhat interwoven, but generally radially oriented, cylindric hyphae; cells 4.2-10.5 µm in diam, smooth or occasionally finely encrusted with a pale brownish pigment, with scattered diverticulate elements. Stipitipellis a layer of parallel, vertically oriented hyphae; cells 3.2-7.6 µm in diam, smooth, thin walled, yellow brown in alkali, giving rise to a vesture of tangled, branched, multiseptate caulocystidia, 2.2-7.6 µm in diam, cylindric, smooth, thin walled. Clamp connections present in all tissues.
Habit, habitat, and distribution: Known from the type collection and recent collections in the southern Appalachians.
Discussion: Pennington (1915a) created a new name (M. fasciatus) for M. anomalus Peck because the latter epithet had been used previously. According to Gilliam (1976), Pennington's concept of M. fasciatus was based on two different taxa, one of which is the holotype of M. anomalus Peck, and the other a species of Marasmius. Because Peck's type of M. anomalus is a species of Gymnopus, a transfer of Pennington's epithet is necessary.
The type collection consists of two flattened basidiomata, portions of which revived slowly but adequately for study. In addition the stipe bases are inserted on the substrate in a manner similar to Gymnopus dichrous, but they are not expanded into a swollen tubercle. Another conspicuous feature is the fused lamellae forming a collar around the stipe apex. In certain respects, G. fasciatus resembles G. dichrous, but the former lacks the voluminous cheilocystidia and the inflated end cells in the pileipellis.

Gymnopus polyphyllus (Pk.) Halling, Mycotaxon 63: 365. 1997. Micro features, Macro image

Marasmius polyphyllus Pk., Ann. Rept. N.Y. State Mus. 51: 286. 1898.
Collybia polyphylla (Pk.) Singer, nom. inval., sine basionym, Agaricales Mod. Tax. 315. 1961 (1962).
Collybia polyphylla (Pk.) Singer ex Halling, Mycologia Mem. 8: 85. 1983.

Pileus (20-)30-60(-70) mm broad, convex with an incurved margin when young, becoming broadly convex to plane or shallowly depressed at the disc, with the margin recurved and sometimes wavy; surface glabrous, even, dry, dark vinaceous brown (natal brown) when young, becoming sordid tan (sayal brown) on the disc and pinkish buff (light pinkish cinnamon, pale pinkish buff, pale pinkish cinnamon) toward the margin, finally nearly whitish overall with a brown (vinaceous brown, tawny) disc; context thin, or sometimes moderately thick, whitish, pliant; odor and taste of garlic (?fetid). Lamellae adnate to adnexed to free or attached by a tooth, crowded, thin, narrow, occasionally forked and anastomosed, white; edges even. Stipe 30-50(-65) mm long, (1-)2-5 mm thick, usually equal, sometimes narrower above or below, pliant; surface pale pinkish cinnamon to vinaceous brown beneath a whitish to light grayish pubescence or coarse tomentum, sometimes subglabrous to pruinose toward the apex, always denser below; interior hollow.

Spore deposit white when fresh, cream buff after storage. Spores 5.6-7(-7.6) x 2.8-3.4(-4.4) µm, lacrymoid to subellipsoid in profile, obovoid to ellipsoid in face or back view, smooth, inamyloid, acyanophilous. Basidia 14-25 x 5-5.6 µm, clavate, four sterigmate, not siderophilous. Pleurocystidia absent. Cheilocystidia scattered, inconspicuous when collapsed on lamellar edge, sometimes fascicled, narrowly clavate, flexuous to diverticulate, 35-56 µm long. Lamellar trama parallel, inamyloid; hyphae 4.2-10.5 µm in diam, sometimes inflated, smooth, thin walled. Pileus trama interwoven, inamyloid; hyphae 5-16 µm in diam, smooth, thin walled. Pileipellis a compact layer of repent, more or less radially oriented, branched hyphae; cells 2-6 µm in diam, usually smooth, but sometimes with finely encrusted walls, with scattered diverticula. Stipitipellis a layer of parallel, vertically oriented hyphae; cells 2-5.6 µm in diam, giving rise to avesture of caulocystidia, branched, septate, cylindric and flexuous, 2-4.2 µm in diam, smooth, thin walled. Clamp connections present in all tissues.
Habit, habitat, and distribution: Scattered, gregarious to subcespitose on hardwood leaf litter. Appearing from July into September.
Discussion: Gymnopus polyphyllus is most easily identified by its crowded lamellae, garlic odor and taste, diverticulate pileipellis hyphae, cheilocystidia, and a hardwood leaf litter substrate.
Other taxa which might be confused with G. polyphyllus are G. confluens, G. kauffmanii, G. subterginus, and G. hariolorum. However, G. confluens, G. subtergina, and G. kauffmanii lack a garlic odor and taste. In addition, G. confluens does not have diverticulate hyphae in the pileipellis and has larger spores. Likewise, G. kauffmanii lacks diverticulate hyphae. Gymnopus hariolorum has a foul odor (like rotten cabbage according to Moser 1978; or garlic according to Kühner and Romagnesi, 1953), and has diverticulate elements in the pileipellis, but lacks cheilocystidia. Gymnopus subterginus also lacks cheilocystidia and has longer spores.

Gymnopus putillus (Fr.) Antonín et al., Mycotaxon 63: 365. 1997. Micro features, Macro image

Agaricus putillus Fries, Syst. Mycol. 1: 129. 1821.
Marasmius putillus (Fr.) Fries, Epic. Syst. Mycol. 377. 1838.
Collybia putilla (Fr.) Singer, Beih. Bot. Centralbl. Abt. B, 56: 163. 1936.
Collybia incrustata O. K. Miller, Jr., in Laursen & Ammirati, Arctic and Alpine Mycology, 126. 1982.

Pileus 9-20(-30) mm broad, convex with an incurved margin when young, expanding and becoming planoconvex to plane with a decurved to straight margin; surface moist to lubricous, glabrous, striate to subsulcate with age, colored a vinaceous brown (natal brown, dark livid brown; dark vinaceous brown) when young and fresh, fading to a cinnamon brown (prout's brown, cinnamon brown, sayal brown, cinnamon rufous) with age; context up to 5 mm thick, pliant, whitish to a pale brownish; odor and taste none. Lamellae adnexed, close, thin, moderately broad, brown (snuff brown, cinnamon brown, sayal brown); edges entire, straight or wavy. Stipe 20-60 mm long, 2-3 mm thick, equal or occasionally slightly enlarged toward the base, pliant to tough; surface dry, concolorous with lamellae above, grayish white below, appearing subglabrous to matted tomentose in wet weather, generally pruinose above and densely whitish pubescent below; base sometimes incrassate; interior hollow.

Spore deposit cream colored. Spores 9-9.8(-10.4) x 3.4-4.2 µm, sublacrymoid to ellipsoid in profile, obovoid in face or back view, smooth, inamyloid, acyanophylous. Basidia 21-31 x 5.6-7 µm, clavate to subclavate, four sterigmate, not siderophilous. Hymenial cystidia absent. Lamellar trama parallel, inamyloid; hyphae 2.8-9 µm in diam, smooth, thin walled. Pileus trama interwoven and smooth walled, more or less radial in orientation and encrusted with a brown pigment just beneath the pileipellis, inamyloid. Pileipellis a thin layer of subgelatinous, interwoven, branched, repent to suberect hyphae; cells 2-5.5(-7) µm in diam, smooth, with refractive and occasionally, slightly indistinct walls, with scattered diverticulate branchlets. Stipitipellis a layer of parallel, vertically oriented hyphae; cells 2.8-5 µm in diam, smooth, slightly thick walled (1.4 µm), hyaline, giving rise to a dense vesture of tangled caulocystidia, (2-)2.8-4.2(-5.6) µm in diam, multiseptate, cylindric, occasionally branched, smooth, thin walled. Clamp connections present in all tissues.
Macrochemical reactions: PDAB--magenta on pileus and lamellae.
Habit, habitat, and distribution: Scattered to gregarious on humus and needle litter under pine. Appearing in September, October, and November. Smith (1949) reported this species from Oregon and Michigan.
Discussion: Distinguishing features of Gymnopus putillus are the habitat on pine needle litter, and the dark reddish brown pileus and lamellae which contrast markedly with the pallid pubescence on the stipe. Microscopically, the subgelatinous hyphae of the pileipellis subtended by a layer of encrusted cells, and the absence of cheilocystidia are diagnostic. An excellent color illustration has been provided by Smith (1949).

Gymnopus subterginus (Halling) Halling, Mycotaxon 1997. Micro features #1, #2

Collybia subtergina Halling, Mycologia Mem. 8: 90. 1983.

Pileus 15-35 mm broad, broadly convex at first with a slightly inrolled and incurved margin, becoming plane to shallowly depressed with the margin decurved and uplifted; surface moist and hygrophanous, occasionally dry, glabrous, even toward the margin at first, striatulate to striate or rugulose subsulcate with age, cinnamon (cinnamon, 6,8C-D7,6) when young, whitish (pale pinkish buff, pale pinkish cinnamon) toward the margin and light vinaceous cinnamon on the disc with age; context whitish, thin, membranous; odor and taste none. Lamellae adnexed, seceding, or nearly free, close to subdistant, thin, narrow (1-2 mm), rarely anastomosed, whitish (pinkish buff, pale pinkish buff); edges even or sometimes wavy. Stipe 25-65 mm long, 3-6 mm thick at the apex, equal to subclavate, sometimes curved at the base, occasionally soft and watery; surface glabrous above, whitish pubescent to tomentose toward the base, more or less concolorous with the pileus beneath the vesture; interior hollow.

Spore deposit white when fresh, cream buff after storage. Spores 8.4-9.8 x (2.8-)3.5-4.2 µm, lacrymoid to subellipsoid in profile, obovoid to ellipsoid in face or back view, smooth, inamyloid, acyanophilous. Basidia 22.4-28 x 6.8-7.8 µm, clavate four sterigmate, not siderophilous. Hymenial cystidia absent. Lamellar trama parallel, inamyloid; hyphae 5-14 µm in diam, smooth, thin walled. Pileipellis an indistinct layer of repent, cylindric hyphae, generally radially arranged; hyphae 2.8-5 µm in diam, mostly smooth, but scattered encrusting pigment occasional and inconspicuous, with diverticulate branchlets and elements. Stipitipellis a layer of parallel, vertically oriented, cylindric hyphae; cells 2-5 µm in diam, smooth, moderately thin walled, giving rise to a dense, tangled vesture of caulocystidia, 2.8-6.4 µm in diam, smooth and thin walled. Clamp connections present in all tissues.
Habit, habitat, and distribution: Scattered, gregarious or subcespitose on dead leaves of Acer, Betula, and Fagus. At present known only from southwestern New England.
Discussion: Gymnopus subterginus is characterized by its hygrophanous pileus, vestured stipe, lack of cheilocystidia, and the presence of diverticulate hyphae in the pileipellis. It has the aspect of Gymnopus hariolorum, G. kauffmanii, G. polyphyllus, and G. terginus, and at first sight might be confused with them. However, G. kauffmanii has cheilocystidia, lacks diverticula, and the hyphal arrangement in the pileipellis is different. Both G. hariolorum and G. polyphyllus have diverticulate hyphae but possess alliaceous odors and have smaller spores. In addition, G. polyphyllus has cheilocystidia. Gymnopus terginus also has cheilocystidia, produces larger spores, and the colors of the basidiomata are paler.

Gymnopus terginus (Fr.) Antonín & Noordel., Mycotaxon 63: 365. 1997. Micro features

Collybia tergina (Fr.) Lundell, Fungi Exsiccati Suecici, No. 1109, 1942.
Agaricus terginus Fr., Syst. Mycol. 1: 128. 1821.
Marasmius terginus (Fr.) Fr., Epic. Syst. Mycol. 377. 1838.

Pileus 3-23 mm broad, convex to applanate; surface glabrous, moist, hygrophanous, even or striate at the margin, ochraceous yellow (76. 1. y Br), paler at the margin; context white to light honey color, thin. Odor not distinctive (or rarely somewhat farinaceous); taste mild. Lamellae adnate seceding to emarginate, close to subdistant, narrow to moderately broad, ivory color; edges somewhat eroded with age, slightly pubescent (under a lens) when dry. Stipe up to 50 mm long, 2.5-3.5 mm thick at the apex; surface pruinose above, strigose on the lower portion, concolorous with the lamellae above, darkening downward and becoming concolorous with the pileus, binding the substrate together.

Spore deposit white when fresh, buff colored after storage. Spores 9.4-11.2 x 3.4-4.6 µm, lacrymoid to ellipsoid in profile, obovoid in face or back view, smooth, inamyloid, acyanophilous. Basidia 24-30 x 5.6-6.4 µm, clavate, four sterigmate, not siderophilous. Cheilocystidia 35-50 x 5-10 µm, subcylindric to flexuous contorted, occasionally subclavate, subfusoid or with diverticulate branchlets, thin walled and hyaline. Lamellar trama parallel, inamyloid; hyphae 2.4-5.6 µm in diam, smooth, thin walled, hyaline. Pileus trama interwoven, inamyloid; hyphae 3.8-10.4 µm in diam, smooth, thin walled, hyaline. Pileipellis an indistinct layer of repent, cylindric hyphae, generally radially oriented; hyphae (2.4-)3.8-8(-13.2) µm, frequently branched, occasionally encrusted with a faint pigment, with scattered diverticulate-contorted branchlets and elements. Stipitipellis a layer of parallel, vertically oriented, cylindric hyphae; cells 3.4-6.8 µm in diam, smooth, thin walled, giving rise to a tangled vesture of flexuous-contorted, rarely diverticulate caulocystidia, 2.4-4.2 µm in diam. Clamp connections abundant in all tissues.
Habit, habitat, and distribution: Gregarious on birch leaf litter in Europe and northeastern United States.
Discussion: The presence of cheilocystidia, long spores, absence of an alliaceous odor, and pallid colors are characteristics that distinguish Gymnopus terginus from other species in the section. Even though I have seen just two North American specimens of G. terginus, they are very close to Moser's topotypical material from Sweden. The somewhat farinaceous odor noted is the only discrepancy, otherwise the specimens I have seen are identical in all respects. Moreover, they are in agreement with Fries's (1882) description and illustration of the species.