Entoloma bichromum Z. W. Liu, Y. Y. Cui & Zhu L. Yang, 2025

Liu, Ze-Wei, Li, Jing, Yang, Zhu L. & Cui, Yang-Yang, 2025, Four new species of Entoloma subgen. Cubospora (Entolomataceae, Agaricales) from Yunnan Province, China, MycoKeys 124, pp. 331-356 : 331-356

Entoloma bichromum Z. W. Liu, Y. Y. Cui & Zhu L. Yang sp. nov.

Figs 2 , 3 , 5

Diagnosis.

Pileus with papilla at center and always dentate at margin. Lamellae edge serrate. Basidiospores cuboid. Pleurocystidia clavate, elongated clavate to cylindrical, always flexuous or furcate, sometimes ventricose. Clamp connections present.

Holotype.

China • Yunnan Province: Tengchong, Diantan Town , 25.2936°N, 98.4506°E, elev. 2200 m, on the soil in a mixed broadleaf-conifer forest, 27 July 2022, Peng-Cheng Yuan 892 ( HKAS 150132 ).

Etymology.

Refers to the pileus exhibiting two color forms: reddish grey or orange white.

Description.

Basidioma small. Pileus 16–26 mm in diam., conical to hemispherical, with a papilla at center, sometimes depressed around the papilla; greyish red (7 B 3, 11 C 4) or reddish brown (8 E 6) at center, disc becoming paler to reddish grey (10 B 2), light orange (6 A 4), or orange white (6 A 2); striations greyish orange (6 B 3) or greyish red (10 D 4), very near the center; surface dry, smooth, not hygrophanous, margin dentate. Lamellae sinuate to subdecurrent, slightly crowded, 1–4 mm wide, with 1–3 tiers of lamellulae, ventricose, pinkish white (10 A 2) to reddish grey (10 B 2), edge serrate and concolorous. Stipe 57–91 × 3–4 mm, central, cylindrical, hollow; apex to middle greyish yellow (4 B 3) or orange grey (6 B 2), base slightly darker to reddish grey (8 B 2) or greyish brown (5 D 3); smooth, with longitudinal striae, base slightly swollen and with white tomentum. Odor and taste not observed.

Basidiospores [97/3/3] 8.8– 9.9 – 10.9 × (8.2) 8.6– 9.4 – 10.2 (10.8) μm [Q = 1.00–1.12, Q = 1.05 ± 0.03], cuboid, most with 4 angles in side-view, rarely with 5 angles, lacking elongated angles. Basidia 35–60 × 9–15 μm, clavate, 4 - spored, colorless. Lamellar edge heterogeneous. Cheilocystidia 27–90 × 6–13 μm, clavate to elongated clavate, with pale yellowish green droplet-like content or hyaline, thin-walled. Pleurocystidia 27–116 × 6–13 μm, clavate, elongated clavate to cylindrical, always flexuous or furcate, sometimes ventricose, with pale yellowish green droplet-like content, sometimes hyaline, thin-walled. Lamellar trama regular, made up of cylindrical hyphae 3–17 μm diam., smooth, thin-walled, occasionally with droplet-like content. Pileipellis a cutis composed of cylindrical hyphae 2–15 μm wide, thin-walled; terminal cells clavate, 24–79 × 7–15 μm; both hyphae and terminal cells in pileipellis with colorless intracellular content, also occasionally incrusting. Stipitipellis composed of longitudinally arranged, cylindrical, and fusiform hyphae 4–14 μm wide; terminal cells clavate to elongated cylindrical, 20–74 × 5–12 μm; both hyphae and terminal cells in stipitipellis with colorless intracellular content. Clamp connections present in all tissue. Refractive hyphae sparsely present in lamellar trama.

Habitat.

Solitary in the litter layer or soil of mixed broadleaf-conifer or broadleaf forests.

Known distribution.

Yunnan Province, China.

Additional materials examined.

China • Yunnan Province: Baoshan , Longling County, 24.7793°N, 98.7926°E, elev. 1900–2000 m, in the litter layer of a mixed broadleaf-conifer forest with moss, 29 August 2022, Jin-Yan Tang 522 ( HKAS 150131 ) .

Notes.

Entoloma bichromum has a serrate lamellar edge, a grayish-red or orange-white pileus, and a concolorous or paler stipe. Entoloma carneum is phylogenetically closely related and morphologically similar to E. bichromum but can be distinguished by its lack of clamp connections and smaller spores (8–9 μm) ( Bi et al. 1986). Moreover, E. pallidoflavum , E. phlebophyllum , E. plicatum , and E. tomentosum are close to the new species in the phylogenetic analysis but can be distinguished from E. bichromum based on the color of the basidiomata and the presence of squamules on the pilei ( Horak 1976; Largent et al. 2013; Chen et al. 2024). Entoloma laccarioides is similar to E. bichromum in the color of the basidiomata, but the former has a subinfundibuliform pileus at maturity and fusoid to utriform pleurocystidia, whereas E. bichromum has a pileus always with a central papilla and clavate, elongated clavate to cylindrical, and narrower pleurocystidia ( He et al. 2015 a). In addition, Entoloma peristerinum resembles E. bichromum in pileus characters, but the former differs by its fibrillose stipe and the absence of pleurocystidia ( Morozova and Pham 2023).

Figures

Figure 2. Basidiospores of four new species of Entoloma subg. Cubospora under SEM. a, b. E. acutiflavum HKAS 150128, holotype; c, d. E. bichromum HKAS 150132, holotype; e, f. E. guttuliferum HKAS 150129, holotype; g, h. E. rufosquamulosum HKAS 130186, holotype. Scale bars: 2 μm.

Figure 3. Basidiomata of four new species of Entoloma subg. Cubospora. a, b. E. acutiflavum HKAS 150128, holotype; c, d. E. bichromum (c) HKAS 150131, (d) HKAS 150132, holotype; e, f. E. guttuliferum HKAS 150129, holotype; g, h. E. rufosquamulosum HKAS 130186, holotype. Scale bars: 10 mm.

Figure 5. Microscopic features of Entoloma bichromum (HKAS 150132, holotype). a. Basidiospores; b. Basidia; c. Cheilocystidia; d. Pleurocystidia; e. Pileipellis; f. Stipitipellis. Scale bars: 10 μm (a – d); 20 μm (e, f).