Tricholoma orientifulvum X. Xu, Y.Y. Cui & Zhu L. Yang, 2020

Xu, Xin, Cui, Yang-Yang & Yang, Zhu L., 2020, Two new species of Tricholoma sect. Genuina (Agaricales) from China, Phytotaxa 443 (2), pp. 155-166 : 161-162

Tricholoma orientifulvum X. Xu, Y.Y. Cui & Zhu L. Yang , sp. nov. Figs. 1 , 4 , 5

MycoBank: MB834641

Etymology:— orientifulvum is proposed for its similarity to T. fulvum .

Type:— CHINA. Yunnan Province: Puer, Simao, alt. 1229 m, in mixed forest with trees of Lithocarpus spp. , Quercus spp. and Pinus kesiya Royle ex Gordon (1840: 8) , 31 August 2019, Xiao-Xia Ding 632 (HKAS 107157).

Basidiomata medium-sized to large. Pileus 4–11 cm diam., plano-convex to applanate, sometimes slightly umbonate at center; surface viscid when wet, red-brown (6 C4-8 , 6 D5-8) to dark red-brown (6 E7-8 , 7 D5- 7, 7E 6-8) at center, brown (5 B3-5 , 6 A2-4 ) to reddish brown (6 B3-6 , 6 C4-7 ) towards margin, glabrous ; margin incurved when young, often undulate when mature. Lamellae sinuate, yellow (3 B2-6 ) to dirty yellow (4 B2-5 ), often with red-brown (6D5-8) dots, crowded ; lamellulae arranged in 2–4 tiers; edges denticulate to sinuate, yellow (3 B2-6 ) to dirty yellow (4 B2-5 ), with red brown (6D5-8) dots. Stipe 8–11 × 0.8–1.2 cm, cylindrical, dirty white (1 A1 , 1 B2 ), brownish (5 A2 , 5 B3 ) to reddish brown (6 B2-5 ), often with red-brown (7 C5-8 ) fibrillose squamules, exannulate, hollow when mature ; basal part white to whitish. Context white, unchanging. Taste unknown. Odor like soap.

Basidiospores [40/2/2] (4.5–) 5–6 (–6.5) × (3.5–) 4–4.5(–5) μm [mean length = 5.3 μm, mean width = 4.2 μm, Q = 1.11–1.42 (–1.46), Q = 1.26 ± 0.10], broadly ellipsoid to ellipsoid, inamyloid, colorless, hyaline, thin-walled, smooth; apiculus small. Basidia 18–30 × 5–7 μm, clavate, 4-spored, hyaline; sterigmata 3–4 μm long; Pleurocystidia and cheilocystidia absent. Lamellar trama regular, composed of colorless, sometimes branching, thin-walled hyphae 3–8 μm in diam. Pileipellis an ixocutis composed of 2.5–6 μm wide cylindrical hyphae with predominantly intracellular pigment, sometimes also with encrusted pigment. Clamps absent in all parts of basidioma.

Habit, habitat, and distribution:—Solitary to scattered on soil in subtropical mixed forests with Fagaceae and Pinaceae ; fruiting in summer in southwestern China at altitude of ca. 1230 m.

Additional specimens examined:— CHINA. Yunnan Province: Puer, Simao, alt. 1229 m, in mixed forest with trees of Lithocarpus spp. , Quercus spp. and Pinus kesiya , 31 August 2019, Xiao-Xia Ding 642 (HKAS 107156).

Figures

FIGURE 1. Phylogenetic analysis of Tricholoma sect. Genuina species inferred from Maximum Likelihood (ML) analysis of ITS sequences. Bootstrap values (ML, ≥ 70%) are shown above or beneath individual branches. Bayesian posterior probabilities (BI, ≥ 0.9) are indicated with thick branches. The two new species are indicated in bold face.

FIGURE 4. Basidiomata of Tricholoma orientifulvum (HKAS 107157, type). Bars = 5 cm Photo by X.X. Ding.

FIGURE 5. Micro-characteristics of Tricholoma orientifulvum (HKAS 107157, type). a. Basidiospores; b. Basidia; c. Lamellar trama; d. Pileipellis. Bars a, c, and d = 20 μm, b = 10 μm. Drawings by Xin Xu.