Mycetinis yunnanensis R.H. Petersen, sp. nov.

Petersen, Ronald H. & Hughes, Karen W., 2017, An investigation on Mycetinis (Euagarics, Basidiomycota), MycoKeys 24, pp. 1-138 : 61-62

14. Mycetinis yunnanensis R.H. Petersen, sp. nov.

Holotype.

China, Yunnan Prov., Simao Pref., vic. Simao, "Red Flag Preserve," N22°47'23", E100°58'33", 4.VIII.1990, coll. RHP, Wu Qiu-xin, Li, TFB 3103a (TENN-F-49172)

Etymology.

Yunnanensis; referring to Yunnan Province, China, where all known collections were found.

Diagnosis.

1) Diminutive basidiomata (pileus 3-8 mm broad; stipe 10-17 × 0.3-0.8 mm); 2) white to off-white, convex pileus; 3) vestured stipe; 4) spores 6-9.5 × 3-4 µm (Lm = 7.3 µm); 5) habitat on dead sclerophylllous leaves; 6) distribution in southwestern China.

Description.

Basidiomata (Fig. 86A, B, D) diminutive, loosely gregarious on midribs of subsclerophyllous leaves. Pileus 3-8 mm broad, convex to shallowly convex, smooth, dull, not glabrous (perhaps suede-like), white to off-white when fresh, with disc slightly pallid grey, when dried becoming ochraceous orange; margin somewhat scalloped, shallowly sulcate, downturned. Lamellae (Fig. 86C) distant, adnexed, seceding on drying, not well-developed (<1 mm broad), thickish, not anastomosing or forked, total lamellae 26-29, through lamellae 8-13, with a few rudimentary lamellulae in one rank, white when fresh, drying to near "ochraceous buff" 5A5; lamellar edge minutely fimbriate, paler than lamellar face. Stipe 10-17 × 0.3-0.8 mm, subinsititious, probably terete when fresh, more or less equal, somewhat compressed in drying, cartilaginous, now "pinkish buff" 6A3 upward, somewhat duller downward, vestured from throughout to upward and downward but missing from midsection (probably through handling); vesture upward scattered and curly, downward becoming delicately strigose or hairy, near "tilleul buff" 7B2. Rhizomorphs not observed. Odor and taste not recorded.

Habitat and phenology.

Known from three collections, all fruiting on fallen sclerophyllous leaves; so far known only from Yunnan Province, China; mid-summer.

Pileipellis near pileus margin (Fig. 87B) a tangle of coarsely diverticulate hyphae; hyphae 3-5 µm diam, thin- to firm-walled, obscurely clamped, often sinuous, with lobe-like diverticula often arising unilaterally; diverticula 3-6 × 2.5-4 µm, rounded, often dichotomous, occasionally capitate. Pileipellis over disc (Fig. 87A) composed of the following: 1) pileal hairs common, probably erect, -75 × 4.5-8 µm, thin- to firm-walled, often minutely roughened, usually subcapitulate; 2) a more or less monolayer of inflated hyphal termini ranging from subcapitulate to sphaeropedunculate (-25 µm diam), often lobed to free-form, often stalked (stalk -14 × 3-4.5 µm, obscurely clamped), thin- to firm-walled; rare thick-walled (wall -1.5 µm thick) individuals observed, usually strongly pigmented; 3) subpellis largely a repent layer of cylindrical hyphae (Fig. 88) 3.5-8 µm diam, thin-walled, inconspicuously clamped, often lightly encrusted with suggestion of delicate annular configuration; diverticulate hyphae of pileus margin rare to absent. Pileus and lamellar tramae loosely interwoven, free (not involved in slime matrix); hyphae 3-6.5(-8.5) µm diam, thin-walled, conspicuously clamped. Hymenium involving some vaguely slimy matrix, obscuring observation and illustration of structure bases and walls. Pleurocystidia (Figs 89, 91A) common, 16-25 × 6-8 µm, fusiform to swollen-fusiform, rounded at apex, inconspicuously clamped, thin- to firm-walled; contents more or less homogeneous, often vaguely partitioned. Basidioles subampulliform, becoming clavate; basidia (Fig. 91B) 20-23 × 9-11 µm, clavate, 4-sterigmate, obscurely clamped; sterigmata slender, curved. Basidiospores (Fig. 91E) 6-7.5(-8.5) × 3-4(-4.5)µm (Q = 1.67-2.33; Qm 1.95; Lm = 6.9 µm), ellipsoid, subamygdaliform, gymnopoid (not tapering proximally), flattened adaxially, often somewhat humped abaxially, thin-walled, inamyloid. Cheilocystidia (Figs 90, 91C) (15-) 18-36(-45) × 9-20 µm, stalked [stalk 5-16(-25) × 3-4(-6) µm, clamped, thin-walled], lumpy or subarbuscular, coarsely diverticulate; diverticula coarse, 3-8 × 2-3.5(-7) µm, knobby to inflated into strangulate dichotomous lobes or clusters of broadly ellipsoid to subglobose cells often capitate, thin-walled, often terminating in pseudosterigma or beak. Stipe medullary hyphae 5-7.5 µm diam, firm- to thick-walled (wall -1 µm thick, hyaline), conspicuously clamped, free (not involved in slime matrix), parallel. Stipe cortical hyphae similar, producing caulocystidia as side branches or termini. Caulocystidia (Fig. 91D) thickly gregarious but not coherent, -120 × 5-7 µm, serpentine, occasionally internally septate, commonly branched (branches often lobe-like), thick-walled (wall -1.5 µm thick, hyaline), usually narrowed at origin, appearing delicately wooly (at 40 ×).

Commentary.

Macroscopically, basidiomata of M. yunnanensis closely resemble those of My. olidus from eastern North America. Experience indicates that these distributions are allopatric, and My. yunnanensis differs from My olidus in habitat (sclerophyll leaves for My. yunnanensis , less sclerotic deciduous leaves for My. olidus ), cheilocystidia (cheilocystidia of My. olidus expanded, utriform or utriform-lobed), caulocystidia (setoiud, straight in My. olidus ) and spores (11-16 × 3.5-4 µm; Lm = 13.7 µm for My. olidus ). Similarity is merely superficial based on basidiomatal size and stature.

The transition of pileipellis from a tangle of diverticulate hyphae at pileus margin to a coarse hymeniform layer of expanded hyphal termini is gradual but dramatic. It parallels the same phenomenon in My. opacus , but otherwise, the two are quite different.

Basidiospores are easily collapsed, quite like those of My. olidus , but somewhat shorter. As several other Mycetinis taxa, large numbers of basidiospores remain lodged on or in the hymenium and are present when microscope mounts are made. Care must be taken, however, for most spores are semi-collapsed and not fit for spore statistics.

Unfortunately, taste and odor of fresh specimens were not recorded. An odor of garlic might be expected, based on its commonality in Mycetinis and particularly in M. olidus .

Specimens examined.

China, Yunnan Prov., Simao Pref., vic. Simao, "Red Flag Preserve," N22°47'23", E100°58'33", 4.VIII.1990, coll. RHP, Wu Qiu-xin, Li, TFB 3103 a (TENN-F-49172; holotype); Yunnan Prov., Jinhong Pref., Xishuangbanna, vic. Menghai, N21°58'15", E100°27'09", nature preserve, 8.VIII.1990, coll. RHP, Wu Qiu-Xin, Li, TFB 3146 (TENN-F-49385); Yunnan Prov., Jinhong Pref., Xishuangbanna, vic. Menghai, N21°58'15", E100°27'09", nature preserve, 8.VIII.1990, coll. RHP, Wu Qiu-Xin, Li, TFB 3145 (TENN-F-49384).