Mycetinis kallioneus (Huhtinen) Antonin & Noordel., 2008. Czech Mycol. 60: 26.

Petersen, Ronald H. & Hughes, Karen W., 2017, An investigation on Mycetinis (Euagarics, Basidiomycota), MycoKeys 24, pp. 1-138 : 25-30

6. Mycetinis kallioneus (Huhtinen) Antonin & Noordel., 2008. Czech Mycol. 60: 26.

Marasmius kallioneus Basionym. Huhtinen. 1985. Mycol. Helvetica 1(5): 342.

Holotype.

Denmark, Greenland, Frederikshåb, Paamiut, N62°00', W49°40', 24.IX.1983, 25 m, coll. T. Borgen, TB.83.83 (C).

Diagnosis.

1) Basidiomata small but robust (pileus 5-23 mm broad; stipe 20-40 × 1.5-2.0 mm); 2) pleurocystidia well-developed; 3) pileus dark brown; 4) spores 11-12 × 8-9 µm; 5) stipe vestured, pruinose to pubescent; 6) boreal distribution (Greenland, Svalbard).

Description.

Basidiomata (Fig. 34) small but robust. Pileus 5-23 mm broad, at first convex with inrolled margin, later plano-convex, more rarely somewhat depressed or papillate, hygrophanous, initially unicolorous and without striation, dark brown (Munsell 5YR4/3, "bone brown" 7F8), later disk brown (Cailleux P67; 7.5YR5/4, "Natal brown" 8E6) and margin lighter (M69; 7.5YR7/4, "olive brown " 5E5), crenulate, transient striate, matt to smooth to naked eye; context thin, supple, light gray brown. Lamellae adnate to shortly decurrent, distant, ventricose, thick, total lamellae (23-)33-35, through lamellae 7-9, up to 3 mm broad with occasional buttresses; lamellar edge smooth to minutely uneven, whitish overall or more rarely concolorous with pileus for ca 2 mm at the pileus margin, lamellae faces greyish pink (M53; 7.5YR7/2, "wood brown" 7C4), now (dried) "Dresden brown" 5E6 to "tawny olive" 5C3 on face, with "pale ochraceous buff" 4A2 to "light buff" 3A2 on edges. Stipe 20-40(-90) × 1.5-2.0 mm, central, dark reddish brown (T29; 5YR3/3, "bone brown" 7F8) to pink clay (ca 5YR6/4, "wood brown" 7C4) or café-au-lait (7.5YR5/2 X 4/2, "olive brown" 5E5 to "clove brown" 6F5), usually tapering somewhat distally, stuffed or partly hollow, not glabrous, ranging from pruinose to pubescent overall to apically pruinose with midsec tion smooth (?through handling) and lower stipe pubescent; lower stipe (1-5 mm from base) minutely wooly or lannose, stipe base consistently appressed-pilose, now (dried) "olive buff" 3B3 (perhaps paler when fresh). Odor strongly alliaceous, devoid of fetid components; taste similar, moderate to strong.

Habitat and phenology.

Presently known from Greenland and Svalbard; collected in "dwarf scrub heathland" and in snow-bank communities, often with stipe disappearing among polytrichous moss; associated woody plants include Salix herbacea , Vaccinium uliginosum and Betula nana and non-woody taxa including Cerastium , Empetrum , Taraxacum . Silene , Dryas , Oxyria , Stellaria and Carex ; reported from late July through September.

Pileipellis (Fig. 35) over pileus margin an irregular hymeniform monolayer of inflated elements, on pileus disc more interrupted and in age becoming commonly collapsed; inflated elements 17-60 × 7-18 µm, ranging from broadly clavate, mitten-shaped to coarsely lobate, usually stalked [stalk 4-35 × 3.5-5 µm, occasionally thick-walled (wall-1.5 µm thick, occasionally pigmented yellow-olive PhC)], conspicuously clamped; inflated portion 8-25 × 7-18 µm, firm-walled, smooth, not with papillate outgrowths, neither amyloid nor dextrinoid. Subtending hyphae tightly interwoven, 3-5.5 µm diam, firm-walled, hyaline, conspicuously clamped. Pileus trama loosely interwoven; hyphae 3-6.5(-8) µm diam, thin- to thick-walled (wall -0.5 µm thick), hyaline, conspicuously clamped, free (i.e. not involved in a slime or gelatinous matrix); "vascular hyphae" common, meandering through pileus and lamellar tramae, 2.5-4 µm diam, with dense, cyanophilous contents, refringent (BF). Hymenophoral trama regular-subregular, in dried material rather dark brown (30 ×); hyphae firm- to thick-walled (walls -0.8 µm thick), inamyloid, non-dextrinoid, conspicuously clamped. Pleurocystidia (Fig. 36) plentiful, 35-62 × 6-7 µm overall (at widest point), narrowly digitate, narrowly fusiform, usually projecting beyond basidia; base 3.5-5 µm diam, conspicuously clamped. Basidioles clavate to subcapitulate; basidia (Fig. 37) 34-55(- 65) × (7-)10-12 µm, clavate, obscurely clamped, exclusively 2-sterigmate; sterigmata -9 × 2-2.5 µm (stout, subcornute); contents heterogeneous, multigranular. Basidiospores (Fig. 40B) (9-)11-12(-13) × (7-)8-9(-9.5) µm (Q = 1.18-1.63; Qm = 1.35; Lm = 11.3 µm), amygdaliform (low hump on abaxial surface, often sublimoniform distally), smooth, thin-walled, inamyloid; contents sometimes uniguttulate. Cheilocystidia (Fig. 38) plentiful on lamellar edge but not rendering the edge sterile, 25-50 × 12-17 µm overall, stalked (stalk 7-35 × 3-4 µm, conspicuously clamped, firm-walled), distal portion expanded to broadly clavate,10-14 µm broad, occasionally bifurcate with lobes rounded, rarely irregularly complex-lobate. Stipe medullary hyphae free (not involved in slime matrix), conspicuously clamped, of three types: 1) 7-14 µm diam, thin-walled; contents heterogeneous; 2) 2-5.5, thin-walled, contents homogeneous; and 3) "vascular hyphae" 3-6.5 µm diam, refringent (PhC), cyanophilous. Stipe corticial hyphae filamentous, 2.5-5.5 µm diam, thin- to firm-walled, tightly packed, strictly parallel, weakly pigmented, producing side branches. Caulocystidia from stipe apex (Fig. 39) cheilocystidial, gathered in clusters, stalked; stalk 5-16 × 3-4 µm, conspicuously clamped, distally expanded into broadly clavate to lobate shapes, 9-12 µm broad, firm-walled. Caulocystidia from lower stipe (Fig. 40A) filamentous, 10->150 × 3.5-5.5 µ, firm- to thick-walled (wall -0.7 µm thick, hyaline), arising as side branches of stipe cortical hyphae, bluntly rounded apically, rarely straight, usually bent or gnarled, without internal clamp connections.

Commentary.

For a discussion of pleurocystidial identification see Materials and Methods under taxonomic characters.

Identification of cheilocystidia is based on two points: 1) experience with other taxa in Mycetinis and other marasmioid and micromphalioid has shown such relatively rudimentary cheilocystidial structures, although some species of Mycetinis exhibit broom cell-like cheilocystidia; and 2) cheilocystidial structures described and illustrated here are limited to lamellar edge and are of greater diameter than basidia and are ventricose-rostrate, not gradually clavate as basidia.

The small pustules of cheilocystidioid caulocystidia at the stipe apex seem unique in the genus. The structures themselves are not surprising, because such resemblance is found in phylogenetically widely separated fleshy fungi (i.e. Strobilomyces , Hymenopellis ).

Specimens examined.

Denmark, Greenland, Frederikshåb, Paamiut, N62°00', W49°40', 19.viii.1985, coll. T. Borgen, TB.85.209 (TUR 040959, topotype). Norway, Svalbard, Longyearbyen, mouth of Blomsterdalen, N78°14', E15°30', 5.VIII.1983, coll. S. Huhtinen (as Marasmius sp.), SH 83/267 (TUR 079363); same location, 31.VII.1983, coll & det S. Huhtinen, SH 83/141 (TUR 079364); Isfjorden, west side of Grønfjorden, Kongressdalen, middle part, N78°02', E14°07', 19.VIII.1966, coll. Esteri Kankainen (as Marasmius sp.), s.n. (TUR 079366); Vestspitsbergen, Kongsfjorden, southeast of Ny Ålesund, N78°55', E12°02', 24.VIII.1966, leg E. Kankainen, s.n. (TUR 072364).