Leucocortinarius brunnescens Zhu L. Yang, Q. Cai, Xue Ping Fan

He, Jin-Fu, Cai, Qing, Fan, Xue-Ping & Yang, Zhu L., 2024, Leucocortinarius brunnescens (Agaricales), a new species from southwestern China, Phytotaxa 664 (4), pp. 263-272 : 267-269

Leucocortinarius brunnescens Zhu L. Yang, Q. Cai, Xue Ping Fan & Jin-Fu He, sp. nov. Figs. 3 , 4

Fungal Name : FN571248

Etymology: — ‘ brunnescens ’ refers to the lamellae of the species becoming brown when dried.

Diagnosis: — Pileus convex to plano-convex, with pale brown to ochraceous brown surface, covered with dirty white, brownish to brown felty squamules; lamellae dirty white to pale ochraceous, becoming brownish to dark brown or even blackish when dried; stipe subcylindrical with a basal marginate bulb; basidiospores 6–7 × 4–5 μm, subfusiform to nearly ovoid, nearly colorless, non-amyloid, non-dextrinoid; basidia 4-spored; pleurocystidia and cheilocystidia absent; clamp connections common. Leucocortinarius brunnescens is closely related and similar to L. bulbiger , but differs from the latter by its darkening lamellae when dried and shorter basidiospores.

Holotype: — CHINA. Yunnan Province: Longling County, Gaoligong Mts. , elev. 2160 m, on the ground, 26 July 2023, GLG-FXP1473 [KUN-HKAS 133134! GenBank Acc. Nos.: PP525617 ( ITS), PP525619 ( LSU), PP525621 ( SSU), PP534487 (tef1-α), PP534485 (rpb2), PP534489 (rpb1)].

Description:— Basidiomata medium-sized, pileate and stipitate. Pileus 5–8 cm diam., convex to plano-convex, sometimes umbonate; surface pale brown to ochraceous brown [5C6–8, 5D6–8], sub-viscid when wet, covered with dirty white, brownish to brown [4A1–3] felty squamules (volval remnants). Lamellae adnexed, moderately close, dirty white to pale ochraceous [4A1–3], becoming brownish, brown to dark brown or even blackish when dried [6E3–5, 6F3–5], with 2–3 tiers of lamellulae. Stipe 7–9 cm long, 0.8–1.2 cm thick, central, subcylindrical, dirty white, dry, fibrillose; cortina arachnoid, whitish, only observed in young specimens; basal bulb marginate, up to 2 cm in diam. at broadest part. Context of cap and stipe whitish, becoming brownish to dark brown when cut. Taste and odor mild but non distinctive.

Basidiospores [80/4/4] 6–7 × 4–5 μm, Q = (1.30) 1.33–1.63 (1.66), Qm = 1.47 ± 0.09, subfusiform to nearly ovoid, thin- to slightly thick-walled, nearly colorless and hyaline, smooth, non-amyloid, non-dextrinoid, cyanophilous in Cotton Blue, weakly metachromatic in Cresyl Blue; apiculus small. Basidia 30–42 × 7.5–9 μm, narrowly clavate, thin-walled, occasionally thick-walled, 4-spored, occasionally 1- or 2-spored; sterigmata up to 5 μm long; basal clamp connections common. Pleurocystidia and cheilocystidia not observed. Subhymenium 20–25 μm thick, composed of hyphae, 3–7 μm diam. Lamellar trama regular to subregular, composed of colorless, thin- to slightly thick-walled hyphae, 3–15(25) μm diam., sometimes with yellow-brown vacuolar pigment. Pileipellis an ixocutis 100–150 μm thick, composed of more or less radially arranged hyphae, 3–7 μm diam., colorless and hyaline or sometimes with yellowish to yellow-brown vacuolar pigment. Volval remnants on pileal surface composed of branching, anastomosing, thin-walled, colorless and hyaline or sometimes with yellowish to brownish vacuolar pigmented filamentous hyphae, 2–5(8) μm diam. Stipe trama composed of longitudinally arranged hyphae, 3–25 μm diam. Caulocystidia absent. Clamp connections common in all parts of basidioma.

Habitat and distribution:—single to gregarious, on soil in broad-leaved forests dominated by Fagaceae or mixed forests dominated by Fagaceae and Pinaceae ; found in summer. Currently only known from southwestern China.

Additional specimens examined:— CHINA. Yunnan Province: Yingjiang County, Xima , elev. 1800 m, 15 July 2003, Zhu-Liang Yang 3677 (KUN-HKAS 42811) ; Tengchong City, Laifengshan , elev. 1700 m, 19 July 2003, Lan Wang 203 (KUN-HKAS 43298) ; Tengchong City, Daxishan , elev. 2200 m, 27 July 2022, GLG-YPC 905 [KUN-HKAS 142246; GenBank Acc. No.: PQ164594 ( ITS)] ; Longling County, Gaoligong Mts. , elev. 2160 m, 26 July 2023, GLG- LGR 222 [KUN-HKAS 140542; GenBank Acc. No.: PQ164593 ( ITS)] .

Specimen of Leucocortinarius bulbiger examined: NORTH MACEDONIA. Bistra County, Sretkóvo, elev. 1100 m, 16 October 2019, Zhu-Liang Yang 6315 [KUN-HKAS 106927; GenBank Acc. Nos.: PP525618 ( ITS), PP525620 ( LSU), PP525622 ( SSU), PP534488 (tef1-α), PP534486 (rpb2), PP534488 (rpb1)] .

Note: Leucocortinarius brunnescens is morphologically similar to L. bulbiger ( Horak 1968, Breitenbach & Kränzlin 2000, Ludwig 2001, Horak et al. 2005, Vizzini et al. 2024). However, the former differs from the latter by its darkening lamellae when dried, slightly shorter basidiospores, and basidia with brown to yellow-brown vacuolar pigment ( Fig. 4 ). The basidiospores of the collection of L. bulbiger made from North Macedonia are [25/1/1] 6.5–7.5(8) × 4.5–5 μm, Q=1.40–1.67 (1.74), Qm = 1.54 ± 0.10. These measurements match well with those reported by Vizzini et al. (2024), which were [(5.6–) 6.6–7.1–7.7 (–9.4) × (3.4–) 4.2–4.6–4.9 (–5.3) µm, Q = (1.29–) 1.44–1.57–1.70 (–2.06)]. In addition, molecular phylogenetic analyses indicated that L. brunnescens is not conspecific with L. bulbiger from Europe ( Figs. 1 and 2 ).

Figures

FIGURE 1. Bayesian inference phylogram of Leucocortinarius based on the concatenated dataset (nrLSU, 5.8S, SSU, tef1-α-exons, rpb2- exons, and rpb1-exons). Bootstrap values over 50 % and Bayesian posterior probabilities over 0.90 are shown along branches. The main suborders are shown in color boxes, and the new species is indicated in bold.

FIGURE 2. Phylogenetic tree of Leucocortinarius inferred from Maximum Likelihood analyses based on the ITS sequences. Bootstrap values over 50 % and Bayesian posterior probabilities over 0.95 are shown along the branches. The new species is indicated in bold.

FIGURE 3. Basidiomata of Leucocortinarius species.A and B. L. brunnescens (type, HKAS 133134). C. L. brunnescens (HKAS 42811). D. L. bulbiger (HKAS 106927). Scale bars = 2 cm. Photos by: Xue-Ping Fan and Zhu L. Yang.

FIGURE 4. Microscopic characteristics of Leucocortinarius brunnescens (A–C, from the type HKAS 133134) and L. bulbiger (D and E, from HKAS 106927). A. Basidiospores. B. Basidia with brown to yellow-brown vacuolar pigment. C. Crushed volval remnants from pileus surface. D. Basidiospores. E. Basidia. Scale bars: A, D=10 μm, B, C, E =20 μm. Drawings by: Zhu L. Yang.