Mycetinis applanatipes (Desjardin) A.W. Wilson & Desjardin. 2005. Mycologia 97: 677.

Petersen, Ronald H. & Hughes, Karen W., 2017, An investigation on Mycetinis (Euagarics, Basidiomycota), MycoKeys 24, pp. 1-138 : 13-15

2. Mycetinis applanatipes (Desjardin) A.W. Wilson & Desjardin. 2005. Mycologia 97: 677.

Marasmius applanatipes Basionym. Desjardin. 1985. Mycologia 77: 899-900.

Diagnosis.

1) Basidiomata of small to moderate size (pileus 10-18 mm broad; stipe 30-40 × 1.5-3 mm); 2) pileus disc reddish brown, margin greyish orange; 3) strong alliaceous odor and taste; 4) entirely vestured, bicolored stipe, typically compressed; 5) cheilocystidia poorly differentiated, clavate to occasionally bifid; 6) spores broadly ellipsoid to subamygdaliform.

Description.

Basidiomata (Fig. 11) of small to moderate size. Pileus 10-18 mm broad, when young strongly convex, in age becoming shallowly convex to plane, rarely shallowly everted, dry, dull, glabrous, subtly subhygrophanous; disc dark reddish brown (8F4-8) overall when young, in age disc remaining dark brown (7F4-8), brown (7E4-6) or light brown (7D5-7); margin incurved when young, becoming decurved to uplifted, entire, even, smooth to minutely rugulose-striate to short sulcate, fading to brownish gray (6C3), greyish orange (5-6B2-4) or pinkish buff. Pilus trama up to 1 mm thick, soft, brown to brownish grey. Lamellae adnate to adnexed, often attached to an adherent pseudocollarium (best seen in dried material), subdistant to distant, thick, total lamellae 40-50, through lamellae 13-16, medium broad to broad (1-2.5 mm broad), rarely anastomosing and intervenose, (fresh) at first buff or orange white (5A2) to greyish orange (5-6B3), mellowing with age, often becoming brown (7E4-5), (dried) "cartridge buff" 30A2, "cream buff" 4A4, “chamois” 4B4; edge even, entire, wavy in age, paler than faces when dried; lamellulae in 1-2 series. Stipe 30-40 × 1.5-3(-4) mm, when young terete and equal, in age becoming compressed and often cleft, typically tapered downward, cartilaginous, hollow, non-insititious, upward pubescent, velutinous in midsection, at base subtomentose to tomentose, with tomentum intricately tangling with substrate, when young, upward buff to orange white (5A2), in age brownish orange (8E4-7), in midsection brownish grey (6C3), downward brown (6-7E5-7) to reddish brown (8E4-8), base dark brown (7B4-8) to dark reddish brown (8F4-8); medulla concolorous with stipe surface. Rhizomorphs and sterile stipes not reported. Odor and taste strongly alliaceous.

Habitat and phenology.

Scattered, densely gregarious to subcespitose in duff under mixed conifers (mainly species of Pseudotsuga , Abies concolor and Pinus contorta ) at elevation above 6000 feet in Sierra Nevada and Cascade Range in California; uncommon; Oct-Nov.

Pileipellis from near pileus margin a roughly hymeniform layer -50 µm thick composed of several elements: 1) pileal hairs (Fig. 11 A–D) 30-90 × 4-6.5 µm, arising as side branches of repent subpellis hyphae, very delicately roughened, occasionally internally clamped, sometimes undulate or shallowly lobate, thin-walled; contents densely homogeneous to heterogeneous; 2) inflated hyphal termini (Figs 11 E–H, 12, 14 A–B) 24-50(-65) × 5-14 µm, stalked, ranging from ventricose-rostrate, subglobose to elongate or complex-lobate, firm-walled, conspicuously clamped, firm-walled (wall -0.6 µm thick, hyaline; 3) similar scattered elements with dense contents, usually branched or lobate; and 4) scattered thick-walled lobate elements (Fig. 14C, D) with densely, strongly pigmented contents. Pileus trama loosely interwoven, composed of hyphae of three types: 1) filamentous, 3-8(-15) µm diam, firm-walled, conspicuously clamped, often swollen at branch-points; 2) filamentous, 3-8 µm diam, firm-walled, delicately to coarsely encrusted (Fig. 14G, H), with crust material in scabs or spiculate deposits; and 3) lobate, free-form, firm- to thick-walled (wall -0.7 µm thick, hyaline) in a loose textura intricata (Fig. 14F). Lamellar trama subparallel to interwoven, composed of smooth, hyaline, inamyloid, cylindric hyphae 3-4 µm broad with walls up to 0.6 µm thick; conspicuously clamped. Pleurocystidia (Fig. 15) common (but not abundant), (35-) 40-75 × 2.5-8 µm, cylindrical to narrowly clavate or occasionally subampulliform-rostrate, conspicuously clamped; contents more or less homogeneous. Basidioles subclavate, not capitulate, conspicuously clamped; contents delicately multiguttulate, increasingly so with maturity; basidia (Fig. 17 A–D) (35-)40-48(-59) × 7-9 µm, clavate, often subcapitulate, obscurely clamped, hyaline, with granular or globular refractive contents, (1-, 2-)4-sterigmate, with sterigmata up to 6 µm long; contents coarsely multiguttulate, refringent (PhC); some collections predominantly two-spored and these with consistently larger spores. Effete basidia not collapsing after evacuation, remaining more or less intact in hymenium ( “husking”). Basidiospores (Fig. 16) (7.5-)8.7-10.2(-12) × 4.8-6(-6.6) µm, µm (Q = 1.18-1.92; Qm = 1.57; Lm = 9.2 µm), pip-shaped, broadly ellipsoid to amygdaliform, hyaline, smooth, inamyloid, white in deposit. Cheilocystidia (Fig. 17 E–H) scattered, uncommon, 33-48(-56) × 6-10 µm, clavate to cylindric-subcapitulate or bifid with two lobes typically unequal in length and occasionally with a few short lateral knobs, with thin, hyaline, inamyloid walls, obscurely clamped, easily disarticulated; contents delicately to coarsely multiguttulate. Stipe medullary hyphae parallel, 2.5-12 µm diam, thin-walled (wall hyaline to pale yellowish brown, inamyloid, walls up to 0.6 µm thick), conspicuously clamped; stipe cortical hyphae 2-4.5 µm diam, strictly parallel, firm-walled, hardly pigmented, producing caulocystidia as side branches and/or hyphal termini. Caulocystidia of upper stipe surface (Fig. 18) (26-)40-100 × 9-15 µm, arising as hyphal termini or side branches, broadly cylindrical, undulate, apically bluntly rounded, hyaline, perpendicular to stipe surface, narrowed somewhat at origin, firm-walled, in clusters or scabs so appearing as delicate floccose scales; contents more or less homogeneous, non-refringent (PhC); caulocystidia of basal tomentum with dark brown, evenly pigmented walls up to 1.2 µm thick.

Commentary.

Numbers of through lamellae is somewhat low for Mycetinis , but the single rank of rudimentary lamellulae is consistent with other species. Stipe length/ pileus diameter ratio is rather low (i.e. stipes are somewhat short, but robust for their length), with several other taxa rather gracile. Habitat on mixed conifer needles is also uncommon, with several other taxa on deciduous leaves or rotten buried wood.

Unexpectedly, the ITS sequence of DED 6628 is close to that of M. prasiosmus from Europe (minimum percent difference = 2.19%). Numerous non-molecular characters differ, however, include basidiomatal size and stature, ecological niche and distribution.

Specimens examined.

United States, California, Placer Co., Yuba Gap, Hwy 80, N39°18'55.66", W120°37'08.15", 6.XI.1983, coll. & det. DE Desjardin (as Marasmius applanatipes ), DED 2469 (SFSU-F- 024633) California, Sierras Co., Chapman Creek Campground, off Hwy 49, N39°37'49.85", W120°32' 37.80, 4.X.1997, coll. Desjardin & Perry, det. DE Desjardin, DED 6628 (SFSU-F-024637); Sierra County, Yuba Pass, N35°19'23.65", W120°35'56.92", 8.X.1983, coll. & det. DE Desjardin, DED 2330 (as Marasmius applanatipes )(SFSU-F- 000646; holotype p.p.); Siskiyou Co., vic. Callahan [N40°18'45", W122°48'05"], Carter Meadow, 20 mi W of Weed, 1.X.1983, coll. & det. DE Desjardin, DED 2236 (SFSU-F- 024634).