Gymnopus sequoiae (Desjardin) R.H. Petersen, 2016

Petersen, Ronald H. & Hughes, Karen W., 2016, Micromphale sect. Perforantia (Agaricales, Basidiomycetes); Expansion and phylogenetic placement, MycoKeys 18, pp. 1-122 : 87-92

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Gymnopus sequoiae (Desjardin) R.H. Petersen

comb. nov.

10. Gymnopus sequoiae (Desjardin) R.H. Petersen comb. nov.


Micromphale sequoiae Desjardin. 1985. Mycologia 77: 894-895.


United States, California, Mendocino Co., Jackson State Forest, junction of state roads 408 & 409, 13.XI.1982, coll & det D.E. Desjardin, DED 1740 ( SFSU-F-000711).


(fide Desjardin 1985). 1) fruiting on needle debris of Sequoia sempervirens ; 2) light brown to flesh-colored, rugulose pileus; 3) lamellae concolorous with pileus; 4) odor mild; 5) grayish-orange to brown pubescent stipe; 6) pileipellis of filamentous hyphae in a slime matrix (no Rameales -structure); 7) poorly developed rhizomorphs.

The following description is a rearrangement of the protologue plus observations on dried material.

Basidiomata (Figs 71 View Figure 71 , 72A View Figure 72 ) pliant, marcescent, reviving. Pileus 6-12 mm broad, when young convex to campanulate, often with a short, acute umbo, in age becoming broadly convex to plano-convex with or without a central papilla, occasionally plane with a shallow central depression; margin when young decurved or slightly incurved, even, entire, in age becoming straight, wavy, crenate, rugulose-striate to rugulose-sulcate ¼ of the distance to center; surface dry to moist, dull glabrous, hygrophanous, at first light brown 7D4-5 overall, rarely with disc reddish brown 8E5-7, in age disc remaining light brown or fading to brownish orange 6C3-4; margin in age fading to brownish orange, greyish orange 6B2-3 or orange white 5A2, in age rarely colored buff overall with a slightly darker disc; pileus trama light brown to brownish orange, soft, up to 1 mm thick. Lamellae adnate, free in age or rarely attached to a pseudocol lar, close to subdistant, narrow to medium broad (up to 1 mm), rarely anastomosing or intervenose, total lamellae = 25-27, through lamellae = 14-16; at first pale greyish orange 6B2, fading in age to pale orange white 5-6A2, typically concolorous with the pileus margin at maturity; edge even, entire, concolorous; lamellulae in 1-2 series. Stipe 20-43 × 0.7-1.5 mm broad, terete or rarely apically compressed and cleft, equal or tapered downward, hollow, cartilaginous, insititious; context concolorous with stipe surface; apex pruinose, off-white, downward pubescent and often with furfuraceous base, when young, apical portion pale greyish orange 6B2, central portion light brown 7D4-6, base dark brown 7F5-7 to rusty brown, in age apex becoming pale brownish orange 7C3, central portion becoming brown 7E4-5, base becoming dark brown 7-8F4-8 or occasionally dark brown overall in age. Rhizomorphs (Fig. 69A View Figure 69 ) short, slender, black, poorly developed, scattered; sterile stipes rare. Taste strongly alliaceous after 1-2 minutes; odor mild or rarely slightly fetid when old and wet.

Habitat and phenology.

Scattered to gregarious on branchlets and leaves of Sequoia sempervirens ; presumably throughout the range of S. sempervirens (at least northern California); October-February.

Pileipellis of inner limb up to 60 µm thick, involved in a slime matrix; slime material heterogeneous with copious crystal suspension, transparent, not totally soluble in KOH, hyaline; hyphae (Fig. 73A View Figure 73 ) 3.6-11 µm diam, repent, unoriented, interwoven, smooth, thick-walled (wall -1.5 µm thick), conspicuously clamped (Fig. 73B View Figure 73 ) but with frequent secondary septa (Fig. 73C View Figure 73 ). Pileus trama loosely interwoven; hyphae smooth, non-gelatinized, 4.2-7.2 µm broad, with hyaline to pale yellowish, inamyloid walls up to 1.5 µm thick. Lamellar trama interwoven, of two hyphal types: 1) filamentous hyphae 3.5-7 µm diam, firm-walled, clamped, not incrusted or gelatinizing; and 2) free-form hyphae, inflated to 13 µm diam, often articulating with neighboring hyphal segments, firm- to thick-walled (wall -0.7 µm thick, hyaline); contents with scattered inclusions (PhC). Pleurocystidia (Fig. 74A-D View Figure 74 ) 21-31 × 7-8 µm, fusiform, clamped; contents homogeneous, dense (PhC). Basidioles broadly clavate, often becoming ampulliform, clamped; contents multigranular; basidia (Fig. 74E-H View Figure 74 ) (21-) 25-30 × (6-)9-11 µm, clavate, hyaline, (2-) 4-sterigmate; contents multigranular; sterigmata up to 4.8 µm long. Basidiospores (Fig. 72B View Figure 72 ) (6-)6.5-7.5(-8) × 3-4 µm (Q = 1.63-2.00; Qm = 1.81; Lm = 6.50 µm) ellipsoid to lacrymoid, hyaline, smooth, inamyloid, white in deposit. Lamellar edge basically fertile; cheilocystidia (Fig. 75 View Figure 75 ) common but scattered, 27-33 × 4.8-6.6 µm, clavate or ventricose-rostrate, occasionally submammilate, hyaline and thin-walled, projecting up to 11 µm beyond basidia. Stipe medullary hyphae (Fig. 76A View Figure 76 ) free (walls not gelatinized), 3-7.5(-11.5) µm diam, thick-walled (wall -1.0 µm thick, hyaline), conspicuously clamped. Stipe cortical hyphae (Fig. 76C View Figure 76 ) 4-8.5 µm diam, thick-walled (wall -1.0 µm thick), strongly incrusted in thick scabs and annuli, pigmented (yellow-brown, PhC), easily shattering in squash mounts. Caulocystidia at stipe apex (Fig. 76B, D, E View Figure 76 ) 10-140 × 9-13 µm, arising from incrusted surface hyphae with somewhat constricted attachment, subventricose and usually tapering slightly distally, thick-walled (wall -2.5 µm thick, hyaline), often strangulate, often secondarily septate and/or clamped. Caulocystidia from stipe base, (Fig. 77B-F View Figure 77 ) 25-170 × 9-13 µm, versiform, irregular in outline with obtuse apices; walls brown, evenly pigmented, -1.2 µm thick.


Care was taken to demonstrate all stages of basidiole maturation to demonstrate the difference between young basidioles and cheilocystidial structures. Basidioles are abundant over all of the lamellar surface and are subspherical at the ear liest stage, soon becoming broadly clavate and developing a subcapitulate upper portion. Basidia remain broadly clavate throughout spore development. Contents of such structures are consistently multigranular. Although cheilocystidia are similar in dimensions and appearance, contents are homogeneous (PhC), and such structures are found only at the lamellar edge. Conversely, pleurocystidial structures are fusiform from their earliest state, merely elongating to mature size and shape. Contents are homogeneous except for a vacuolated area in midsection (perhaps nucleus; PhC).

Caulocystidia arise as side branches of stipe surface, incrusted hyphae. Early stages of caulocystidial development often bear a shagreened surface but soon becoming smooth. A unique character is the frequent internal secondary septation, as well as occurrence of a clamp connection near caulocystidial origin.

Specimens examined.

California, Humboldt Co., Redwood National Park , Davidson Rd. , N41°12'51", W124°00'12", 24.X.1992, coll & det DE Desjardin, DED 5546 ( SFSU-F-025665); Redwood National Park , Davidson Rd. , N41°12'51", W124°00'12", 24.X.1992, coll & det DE Desjardin, DED 5546 ( SFSU-F-025665); Mendocino Co. , vic. Fort Bragg , Simpson Lane , 28.IX.1986, coll & det H.D.Thiers, HDT 50541 View Materials ( SFSU-F-025669); Jackson State Forest , Hwy 408 at junction with road to Mendocino Woodlands, 21.XI.2015, coll & det DE Desjardin, DED 8802/ TFB 14620 View Materials ( TENN-F-69325); Jackson State Forest, along Hwy 409 car 1 mi from junction of Hwy 408, 18.XI.1995, coll & det DE Desjardin, DED 6316 ( SFSU-F-025662); same loca tion, 13. Nov. 1982, DED 1740 (holotype); same location, Hwy 409, 13.XII.1990, coll & det D.E. Desjardin, DED 5023 ( SFSU-F-025663); same location, "Aleuria Glen," 29.X.1990, coll H.D. Thiers, det D.E. Desjardin, DED 5012 ( SFSU-F-025668) GoogleMaps .