Tricholomopsis mitirubicunda L. Fan & N. Mao, 2021

Mao, Ning, Xu, Yu-Yan & Fan, Li, 2021, Three new species of Tricholomopsis (incertae sedis) from North China based on morphological and molecular data, Phytotaxa 507 (2), pp. 155-166 : 161-163

Tricholomopsis mitirubicunda L. Fan & N. Mao , sp. nov. ( Figs. 2 , 3 )

MycoBank:—MB839213

Diagnosis:— Pileus 60–80 mm diam, yellow-brown to red-brown, covered with yellow-brown to red-brown fibrillose scales, lamellae crowded, free, white to pale yellowish, basidiospores ellipsoid, Q = (1.33–) 1.42–1.67 (–1.75), cheilocystidia narrowly clavate to sphaeropedunculate, pleurocystidia abundant.

Etymology: — ‘ mitirubicunda ’, refers to the soft pink color of the pileus margin and stipe.

Holotype:— CHINA. Shanxi Province, Yicheng County, Shihe Forest Farm, 35°29’40’’N, 112°5’41’’E, elev. 1960 m, 20 August 2019, on fallen wood in a forest of Pinus sp. , H. Liu LH 688 ( BJTC FM 649 ).

Description:— Basidiomes growing singly or in clusters. Pileus 60–80 mm diam, plano-convex with inflexed or turned up margin, margin cracking with age, yellow-brown (#8b4513) to red-brown (#bb6528), densely covered with small, yellow-brown (#8b4513) to red-brown (#bb6528) fibrillose scales, margin of pileus red-violet (#c71585) with tints of soft pink (#de6fa1). Context not recorded. Lamellae 3.0–5.0 mm broad, crowded, adnate to subdecurrent, white to pale yellowish (#ffffeb), edge entire. Stipe 60–90 × 23–25 mm, cylindrical, straight to curved, smooth, at first whitish (#faebd7) to pale yellow (#ffffeb), then soft pink (#de6fa1) and moderate orange (#cc8236). Taste not recorded. Smell indistinct. Spore print white.

Basidiospores [30/1/1] (4.5–) 5–6 (–7) × (3.0–) 3.5–4 (–4.5) μm; [Q = (1.33–) 1.42–1.67 (–1.75), avQ = 1.50 ± 0.14]; mostly ellipsoid, some oblong-ellipsoid, smooth, thin-walled, hyaline, or with one large oil droplet. Basidia 28–40 × 5–7 μm, (2–)4-spored, cylindrical to narrowly clavate, often slightly constricted in the median part, with basal clamp connection; sterigmata narrow 3–6 μm long. Cheilocystidia prominent, large, often in clusters, (40–) 60–90 × (14–) 16–28 μm, variable in size and shape, mostly narrowly clavate to sphaeropedunculate, but also fusiform or broadly ellipsoid slightly thick-walled, hyaline. Pleurocystidia abundant, 38–50 × 5–6.5 μm, cylindrical or narrowly clavate, slightly flexuose, hyaline, thin-walled. Lamellar trama composed of regular, parallel to subparallel long, cylindrical, or slightly inflated hyphae, 5–34 μm diam, hyaline or with a fine granular intracellular pigment. Pileipellis a cutis, composed of hyphae 2.5–16 μm diam with homogeneous pale yellow to bronze pigment, yellow-brown intraparietal pigment and hyphae becoming erect and forming fascicles at intervals. Stipitipellis a thin cutis of cylindrical hyphae of 4–15 μm diam, with hyaline to pale yellow-brown content. Clamp connections present in all tissues.

Habit, habitat and distribution:—single or grouped on the trunk of a dead tree in a forest of Pinus sp. , to date only known from Shanxi Province, China.

Figures

FIGURE 2. Basidiomes of the three new species. a. Tricholomopsis galeata (BJTC FM1107, holotype); b. Tricholomopsis pallidolutea (BJTC FM1184, holotype); c–d. Tricholomopsis mitirubicunda (BJTC FM649, holotype). Scale bars: a, c, d = 20 mm; b = 10 mm. Photos by: Li Fan.

FIGURE 3. Microscopic features. Tricholomopsis galeata (BJTC FM1107, holotype) a. Basidiospores b. Cheilocystidia c. Pileipellis elements; Tricholomopsis pallidolutea (BJTC FM1184, holotype) d. Cheilocystidia e. Basidiospores f. Pleurocystidia g. Pileipellis elements; Tricholomopsis mitirubicunda (BJTC FM649, holotype) h. Cheilocystidia i. Basidiospores j. Pleurocystidia k. Pileipellis elements. Scale bars: h = 20 μm; a, b, c, d, f, g, i, j, k = 10 μm; e = 5 μm. Drawings by: Ning Mao.