Gymnopus glabrosipes 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 : 40-43

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Gymnopus glabrosipes R.H. Petersen

sp. nov.

4. Gymnopus glabrosipes R.H. Petersen sp. nov.


United States, Washington, Snowhomish Co., Hwy 92, Perry Creek Trail, 24.VI.1993, coll GR Walker (as Micromphale perforans ), GRM 410 ( WTU-F-9309).


Glabro- = Latin, smooth; pes = Latin, foot, referring to the glabrous-shining stipe.


1) A morpho-species (no DNA sequences available; 2) stipe glabrous-shining; 3) fruiting on dead Tsuga needles; 4) lamellae suffusing brown from edge when bruised or dried; 5) stipe 15-25(-50) × 0.4-1 mm, robust; 6) stipe medullary hyphae involved in slime matrix.

The following description is based solely on dried specimens.

Basidiomata (Fig. 28 View Figure 28 ) diminutive with robust stipe. Pileus 4-9 mm broad, plano-convex to plane, matt, smooth, more or less unicolorous, hardly sulcate at margin, more or less unicolorous, dark brown ("carob brown" 7F7, "chestnut brown" 7E4); context near "olive buff" 3B3, reluctantly bruising to near "buffy brown" 6D4 when cut or bruised. Lamellae adnexed to free, distant, with no anastomosis or interveining, thickish, near "olive buff" 3B3 (dried), bruising to dull "buffy brown" 6D4 from edge when bruised or dried; lamellulae rare, rudimentary. Stipe 23-30(-50) × 0.7-1.2 mm, robust, terete, equal, insititious, glabrous-shining overall, delicately sulcate-ridged, stuffed, apically "buffy brown" 6D4, soon downward "chaetura drab" 2F2 to "chaetura black" 2F3 overall; stipe medulla white. Rhizomorphs extensive but inconspicuous, black, polished, filiform, -14 × 0.2-0.4 mm, curly, branched with branches spur-like. Taste and odor not recorded.

Habitat and phenology.

Fruiting on needles of Tsuga (associated with Abies ); mid-summer.

Pleipellis a layer of unoriented, tightly interwoven, repent, strongly encrusted hyphae involved in a gelatinous or slime matrix; superficial hyphae 5-7.5 µm diam, thin- walled, conspicuously clamped, strongly encrusted (Fig. 29A View Figure 29 ); incrustation material -2 µm thick, in scabs and vaguely annular patterns; subpellis hyphae 6-11 µm diam, thick-walled (wall 1.5-3 µm thick, hyaline), smooth to weakly encrusted; crust material <1 µm thick, in small scabs and vaguely defined annular patterns, sometimes flake-like on surface of slime sheath (Fig. 29B View Figure 29 ). Inner subpellis hyphae 7-11 µm diam, smooth, thick-walled with wall slowly (in KOH) swelling or gelatinizing (Fig. 29C View Figure 29 ), conspicuously clamped. Lamellar trama loosely interwoven; hyphae 2.5-3.5 µm diam, thin-walled, conspicuously clamped, often with thin slime sheath. Hymenium composed of pleurocystidia and basidia, gelatinizing (in KOH) from trama outward, eventually reducing basidial and pleurocystidial bases to gelatinous matrix. Pleurocystidia (Fig. 30B-D View Figure 30 ) 23-30(-42) × 4-7 µm, narrowly fusiform without partitioned contents, conspicuously clamped. Basidioles narrowly clavate; basidia (Fig. 30A View Figure 30 ) 29-32(-39) × 9-11 (at widest point), clavate, conspicuously clamped, 4-sterigmate; contents homogeneous. Basidiospores not observed. Cheilocystidia not observed. Stipe medullary hyphae appearing dimitic, without slime matrix; 1) 1.5-7.5 µm diam, thick-walled (wall -1 µm thick, hyaline, non-refringent; PhC) (Fig. 31 View Figure 31 ), frequently clamped, often branched, loosely interwoven, meandering among refringent, wider hyphae; and 2) 5-12 µm diam, tapered at both ends, thick-walled (wall gelatinizing -6 µm thick, strongly refringent, PhC), long-celled, clamped. Stipe cortical hyphae strictly parallel, 2-4.5 µm diam, thick-walled (wall -1 µm thick, pigmented yellow-brown), clamped, minutely roughened outward (perhaps a roughened mucoid film). Caulocystidia absent.


Extraction of usable DNA from the two specimens examined was unsuccessful, so phylogenetic placement of G. glabrosipes remains unknown.

Pileipellis involved in slime matrix, pileus tramal hyphae with gelatinizing walls, basidia and pleurocystidial bases strongly gelatinizing and absence of cheilocystidia all are diagnostic of the Mi. perforans complex. Conversely, the glabrous-shining stipe is not characteristic of that clade.

Two pilei were assessed for diverticulate hyphae with no success. Pileipellis was the same in both.

Macromorphologically, basidiomata are reminiscent of those of Ma. thiersii , with dark chocolate brown pileus and insititious, brown-black stipe. From M. thiersii , WTU 9309 differs in glabrous-shining stipe (minutely velutinous in Ma. thiersii ), and absence of diverticulate hyphae (present in Ma. thiersii ). WTU 9309 is a Micromphale , Ma. thiersii belongs in Marasmius sect. Androsacei .

Although basidiospores have not been observed (in both specimens examined), basidiospores in this clade are quite uniform, and the organism’s identification is not dependent on these statistics.

Specimens examined.

Oregon, Clackamas Co., road to Mt. Hood at 2-3 mi post, 25.VI.1995, coll MT Seidl, J Roger, N Weber (as Marasmius androsaceus ), MTS 4078 ( WTU-F-8919); Washington, Snowhomish Co., Hwy 92, Perry Creek Trail, 24.VI.1993, coll GR Walker (as Micromphale perforans ), GRM 410 ( WTU-F-9309).