Tricholomopsis pallidolutea 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 : 160-161

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

MycoBank:—MB839212

Diagnosis:— Pileus 14–27 (–57) mm diam, light yellow to pale yellow, covered with dark orange fibrillose scales, basidiospores ellipsoid to almost cylindrical, Q = (1.50–) 1.67–2.0 (–2.67), cheilocystidia cylindrical to clavate, pleurocystidia abundant.

Etymology:—‘ pallidolutea ’, refers to the pale yellow color of the basidiomes.

Holotype: CHINA. Shanxi Province, Ningwu County, Damiao Village, Luya Mountain , elev. 2010 m, 5 September 2020, on the trunk of a dead tree in a coniferous forest dominated by Larix principis-rupprechtii, H. Liu LH1254 ( BJTC FM1184 ).

Description:— Basidiomes growing singly or in clusters. Pileus 14–27 (–57) mm diam, hemispherical and convex with an inflexed margin, dry, light yellow (#ffff8c) to pale yellow (#ffffd8) when young and fresh, covered densely with small, dark orange (#a5682a) fibrillose scales. Context yellowish, thin. Lamellae 1.5–2.0 mm broad, free, adnate to subdecurrent, pale yellow (#ffffeb), edge entire; lamellulae in 1–2 tiers, concolorous with lamellae. Stipe 20–98 × 5–8 mm, cylindrical, hollow, straight, smooth, dry, moderate orange (#d69b5e). Taste not recorded. Smell indistinct. Spore print white.

Basidiospores [30/2/2] (4–) 6–7 (–9) × (2.5–) 3–4 (–5) μm; [Q = (1.50–) 1.67–2.0 (–2.67), avQ = 1.77 ± 0.33]; ellipsoid to almost cylindrical, smooth, thin-walled, hyaline, usually containing one large oil droplet. Basidia 26–35 (–38) × 5–8 μm, (2–)4-spored, narrowly clavate; with basal clamp connection. Lamella edge sterile. Cheilocystidia prominent, often in clusters, (35–) 45–65 × (8–) 12–18 (–21) μm, cylindrical to clavate, slightly thick-walled, hyaline, occasionally with yellow pigment. Pleurocystidia abundant, 35–45 × 5–7 μm, cylindrical or narrowly clavate, slightly flexuose, hyaline, thin-walled. Lamellar trama composed of regular hyphae 3–13 μm diam, cells cylindrical to slightly inflated, pale yellow, crystals sometimes present among the lamellar trama hyphae. Pileipellis a cutis, composed of densely arranged parallel to slightly inflated hyphae, 3–20 μm diam, with pale yellow to brown intraparietal and homogeneous or fine granular intracellular pigment, rising at intervals to form fascicles . Stipitipellis a thin cutis of regular cylindrical hyphae of 3–14 μm diam, with hyaline to pale yellow-brown content. Clamp connections present in all tissues.

Habit, habitat and distribution:—on the trunk of a dead tree in a coniferous forest dominated by Larix principisrupprechtii , to date, only known from Shanxi Province, China.

Additional specimens examined:— CHINA. Shanxi Province, Jiaocheng County, Guandi Mountains , 37°51’40’’N, 111°27’8’’E, elev. 1930 m 5 September 2018, on the trunk of a dead tree in a forest of Larix principis-rupprechtii, H. Liu LH 398 ( HSA398 ) ; ibid. 37°51’37’’N, 111°27’0’’E, elev. 1880 m, 31 August 2018, on the trunk of a dead tree in a forest of Larix principis-rupprechtii, H. Liu LH 321 ( HSA321 )

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.