Entoloma subtenuicystidiatum

Entoloma subtenuicystidiatum Xiao Lan He & T.H. Li

MycoBank number: MB 563509

Pileus 8–25 mm abroad, plano-convex, truncate-conical to hemispherical with central depression, not hygrophanous, dry, translucently striate almost up to center, becoming sulcate, minutely squamulose on disc, glabrous or very slightly fibrillose elsewhere, yellow to dark beige (5A3–6A3), slightly darker in the grooves and somewhat reddish brown at the disc. Lamellae adnate, ventricose, subdistant to moderately crowded, thin to moderately thick, up to 3 mm broad, white becoming pink, with pale pinkish brown or rarely concolorous edge, with three tiers of lamellulae. Stipe central, 40–60 mm in length, 1–2 mm in width, equal, cylindrical, paler than pileus, almost white or pinkish to very pale pinkish brown (5A2–5A3), hyaline to subhyaline, glabrous, polished, fragile, hollow, dry, with white basal mycelium. Context thin, nearly membranous. Odor and taste not distinctive. Basidiospores 9.5–13 × 7.5–9 μm (x = 11.5 ± 0.5 × 8.3 ± 0.4 μm), Q = 1.2–1.6 (Q = 1.4 ± 0.1), heterodiametric, mostly 6–9-angled in side-view with pronounced angles, thick-walled. Basidia 28–35 × 9–10 μm, clavate, 2–4-spored, sometimes 1-spored, sterigma up to 2 μm wide, clampless. Lamellar trama regular of cylindrical elements. Lamellar edge sterile or heterogeneous. Cheilocystidia 40–70 × 7–10 μm, clavate, hyaline, nearly colorless, thin-walled. Pleurocystidia absent. Pileipellis a cutis with a transition to a trichoderm at center, terminal elements 7–15 μm wide. Pileitrama regular, made up of cylindrical hyphae, up to 20 μm wide. Pigment yellow, encrusting in pileipellis. Brilliant granules present in all tissues. Clamp connections absent in all tissues. Oleiferous hyphae present in lamellar trama and pileal trama.

Habitat. Common in South China, scattered on grasslands with Cynodon dactylon and Zoysia tenuifolia.

Notes: Entoloma subtenuicystidiatum is conspicuous on account of the pale-colored pileus with a darker and minutely squamulose central depression, the pale pinkish brown lamellar edge, the slender hyaline stipe, the large spores with pronounced angles in side view, and the presence of cheilocystidia. Entoloma subtenuicystidiatum is very common in Fuzhou in Jiangxi Province. The habitat on grasslands, the small pileus, and the polished stipe suggests that E. subtenuicystidiatum belongs to the section Cyanula. It resembles the Australian E. tenuicystidiatum G. Gates & Noordel. in the macroscopic appearance and the large spores with pronounced angles. However, E. tenuicystidiatum has a pale brown to brown pileus, larger 6–7-angled spores (10–15 × 8.0–10 μm), narrower terminal elements (to 10 μm wide) in the pileipellis, cylindrical cheilocystidia with brown intracellular pigment, and golden-brown intracellular pigment in the pileipellis. The European E. xanthoserrulatum Noordel. & Vauras and E. politoflavipes Noordel. & Liiv are also close to E. subtenuicystidiatum macroscopically. E. xanthoserrulatum differs by having a blue lamellar edge, smaller spores (8.5–10.5 × 6–8 μm) with 5–6 regular angles in side view and cylindrical cheilocystidia with bluish intracellular pigment. Entoloma politoflavipes is distinguished by having smaller spores (7–9.5 × 6–8.5 μm), the absence of cheilocystidia, and the presence of abundant clamp connections.

Fig. 1 Phylogeny of the relationship of the four new species with related species generated by Maximum Parsimony analysis based on ITS sequences. Values above or below the branches are parsimony boostrap (>50%).