Gymnopus sublaccatus 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 : 93-101

11. Gymnopus sublaccatus R.H. Petersen sp. nov.

Holotype.

Canada, British Columbia, Victoria, Saanich Peninsula, Observatory Hill, N48.5262°, W123.422°, 4.XI.2011, coll & det O. Ceska (as Marasmius androsaceus ), UBC-F-25212.

Etymology.

sub- = Latin: less than; laccatus = Latin: appearing polished or varnished, referring to varnished appearance of dried pileus.

Diagnosis.

1) Fruiting on needles of Thuja (and Pseudotsuga ); 2) cheilocystidia rare, small, clavate, smooth, without setulae; 3) stipe near ochraceous buff above, downward rusty brown; 4) pileal hairs usually smooth, rarely roughened; 5) dried pileus sublaccate; 6) pileipellis of smooth, unencrusted, repent hyphae in slime matrix; 7) rhizomorphs inconspicuous, with minute black basal pad.

The following description is based solely on dried material.

Basidiomata (Fig. 78A ) diminutive. Pileus 2-8 mm broad, convex to plano-convex, minutely laccate, vaguely tuberculate, not striate or sulcate; disc about "sayal brown" 6C5 to "ochraceous buff" 5A5; limb and margin about "light ochraceous buff" 5A4 to "tilleul buff" 7B2. Lamellae (Fig. 78A ) pseudocollariate (dried), adnate, distant, thickish, total lamellae = 20-23, through lamellae = 9-11, now (dried) "tilleul buff" 7B2 to "olive buff" 3B3; lamellulae in a single rank. Stipe 18-25 × 0.6-0.8 mm, terete, equal, hollow to lightly stuffed, subinsititious, minutely shaggy to silky above, downward becoming minutely barbed (35 ×), above about "ochraceous buff" 5A5, downward through "army brown" 8D5, increasingly dark to rusty brown ( “Prout’s brown" 5F6 to "Vandyke brown" 7E6), sometimes slightly expanded at base; stipe medulla white. Rhizomorphs (Fig. 78C ) (if produced) inconspicuous, often represented only by minute, black basal pads. Taste and odor not recorded.

Habitat and phenology.

Fruiting on needles of Thuja plicata , less often on Pseudotsuga menziesii ; British Columbia; Autumn to early Winter.

Pileipellis involved in a slime matrix which includes detersile encrusting material, of the following elements: 1) pileal hairs (Fig. 79 ) -150 × 3-6 µm, erect, firm-walled, smooth or rarely weakly roughened, slightly subcapitulate; 2) repent hyphae 4.5-7.5 µm diam, firm-walled, conspicuously clamped but often secondarily septate, without discernable slime sheath. Pileus and lamellar tramae loosely interwoven; hyphae 3-5.5 µm diam, smooth, firm-walled, without slime sheath, conspicuously clamped. Pleurocystidia (Fig. 80A-D ) 25-35(-41) × 7-8 µm, fusiform to clavo-fusiform, without partitioned contents but with vague vacuolated area in midsection (PhC), conspicuously clamped. Basidioles (Fig. 80E ) clavate; basidia (Fig. 80F-H ) 24-27 × 8-9 µm, clavate, 4-sterigmate, clamped; contents multigranular at maturity; effete pleurocystidia and basidia emptying but not col lapsing ( “husking” Fig. 81B ); subbasidial hyphae (Fig. 81A ) rupturing at clamp connections, appearing beaded. Basidiospores (Fig. 78B ) (6.5-)7-7.5(-8) × (3.5-)4-5 µm (Q = 1.40-1.88; Qm = 1.67; Lm = 7.20 µm), rotund-ellipsoid, smooth, thin-walled, inamyloid. Cheilocystidia (Fig. 82 ) very locally common, usually rare to absent, 14-22 × 8-12 µm, clavate to utriform, thin-walled, obscurely clamped; contents homogeneous. Stipe medullary hyphae (Fig. 81C ) 4-12 µm diam, strictly parallel, apparently free (no discernable gelatinized matrix, hyaline, thick-walled (wall -0.7 µm thick, hyaline, non-gelatinized), obscurely clamped, often with small side-branches ranging from lobate to rudimentarily branched. Stipe cortical hyphae 4-8 µm diam, strictly parallel, apparently free, thick-walled (wall -1.2 µm thick, especially at stipe surface), pigmented (yellow-brown, KOH + PhC), appearing moderately dextrinoid (IKI + PhC), or not so (IKI + BF), often producing broad-based side branches. Caulocystidia (Figs 83 , 84 ) -45 µm at stipe apex, -140 µm at stipe base, × 5.5-10 µm, ranging from lobate to elongate-digitate, without basal clamp, often internally secondarily septate, sometimes branched in one rank, thick-walled [wall -4 µm thick, often occluding cell lumen, pigmented (yellow-brown PhC)].

Commentary.

With slime matrix covering the pileus surface and involving hymenial structures, with characteristic clavate cheilocystidia and with vestured stipe, UBC 25212 seems certain to belong in sect. Perforantia . There it joins G. perforans , G. foliiphilus and G. sequoiae with the same general characters. From Ma. androsaceus , G. sublaccatus differs in pigmented (not black), vestured stipe. If its substrate preference is limited to Pseudotsuga , this constitutes another difference. Finally, pileipellis of G. androsaceus is characterized by diverticulate hyphal segments and broom cell-like hyphal termini, unlike that of G. sublaccatus which lacks these structures.

Basidiomata of G. sequoiae resemble those of M. sublaccatus in stature and size, but seems limited to fruiting on needles of Sequoia sempervirens in northern California. Cheilocystidia are shaped like an incandescent bulb, sometimes slightly askew, but otherwise quite typical of cheilocystidia in this taxonomic complex (compare, for example, those of G. bulliformis and of G. sequoiae ). Difficult to distinguish from immature basidia, such cheilocystidia are less obscure after several sightings.

Specimens examined.

Canada, British Columbia, Queen Charlotte Islands, Burnaby Island, Section Cove , N52°24'35", W131°19'55", 8.IX.2006, coll PK Kroeger (as Marasmius androsaceus ), PK 489 ( UBC F18168 ) ; Queen Charlotte Islands , N52°21'23", W131°24'24", 11.IX.2008, coll P. Kroeger (as Marasmius androsaceus ), PK 5904 ( UBC F16670 ) ; Queen Charlotte Islands, Ellen Island , N52°09', W131°06', 10.IX.2004, coll & P. Kroeger, B. & C. Kendrick, J. Brown, (as Marasmius androsaceus ), PK 2932 ( UBC F15356 ) ; Queen Charlotte Islands, Ross Island , N52°10', W131°07', 2.IX.2006, coll P. Kroeger (as Marasmius androsaceus ), PK 4347 ( UBC F17675 ) ; Victoria, Saanich Peninsula, Observatory Hill , N48.5262°, W123.422°, 4.XI.2011, coll & det O. Ceska (as Marasmius androsaceus ), UBC-F-25212 (holotype) .

Figures

Figure 78. Gymnopus sublaccatus. A Basidiomata showing adventitious rhizomorphs and stipe insertion to pileus B Basidiospores C Substrate scales with back spots and rhizomorphs. Standard bars: A = 20 mm; B = 5 µm; C = not to scale. UBC 25212.

Figure 79. Gymnopus sublaccatus. Pileipellis elements. A-E Pileal hairs F Secondary septa of pileipellis hypha. Standard bars = 10 µm. UBC 25212.

Figure 80. Gymnopus sublaccatus. Hymenial elements. A-D Pleurocystidia E Basidiole F-H Basidia. Standard bars = 10 µm. UBC 15356.

Figure 81. Gymnopus sublaccatus. A Subbasidial hyphae appearing beaded B Effete hymenial structures without collapse (" husking ") C Stipe medullary hyphae. Standard bars = 10 µm. UBC 25212.

Figure 82. Gymnopus sublaccatus. Cheilocystidia. Standard bars = 10 µm. UBS 15356.

Figure 83. Gymnopus sublaccatus. Caulocystidia from stipe apex. Standard bars = 10 µm. UBC 25212.

Figure 84. Gymnopus sublaccatus. Caulocystidia from stipe base. Standard bars = 10 µm. UBC 25212.