Lactarius baiyunensis, Huang & Lin & Li & Qiu, 2022

Huang, Xiao-Xia, Lin, Zhi-Jun, Li, Si-Duo & Qiu, Li-Hong, 2022, A New Species of Lactarius subg. Lactarius (Russulaceae) from Baiyun Mountain, China, Phytotaxa 554 (3), pp. 245-256 : 250-252

Lactarius baiyunensis sp. nov. X.X. Huang & L.H. Qiu, ( Figs 2 , 3 )

Mycobank: MB 842079

Diagnosis:— Lactarius baiyunensis differs from the other orange-white species within Lactarius subg. Lactarius by a lamellae edge without cheilocystidia and an ixotrichoderm for a pileipellis.

Holotype:— CHINA. Guangdong Province, Guangzhou City, Baiyun Mountain , 21 August 2021, L. H. Qiu, B21082143 ( GDGM 87010 ).

Etymology:—the epithet ‘‘ baiyunensis’’ refers to the type location, Baiyun Mountain.

Description:— Fruitbodies medium-sized, 20–50 × 15–35 mm. Pileus 20–50 mm in diam, center depressed, shallowly infundibuliform when mature, margin slightly in-rolled in youth, expanding with maturity; surface smooth, greasy and sometimes viscid; brownish orange (#c79e85) and light brown (#c08b61) at the center, becoming milky white (#d6cfc9) towards the edge, azonate or inconspicuously zonate. Context 3–4 mm thick at center, 1–2 mm at margin, milky white, pale yellowish brown (#f7dea6) near the pileus. Lamellae 2–4 mm broad at center, close to crowded 2–3 tiers of lamellulae, adnate to decurrent, milky white (#d6cfc9) when young, brownish orange (#c79e85) or light brown (#c08b61) when mature, unchanging when damaged. Stipe 1.5–3.5 × 0.8–1.2 cm, central, cylindrical, sometimes tapering upwards, solid in youth becoming hollow with age, surface dry, white, often with irregular brownish spots. Odor mostly non distinct, sometimes fruity. Taste and spore print unrecorded. Latex scarce, white, unchanging when exposed.

Basidiospores [80/4/4] (3.3–) 3.6–4.3–4.9 (–5.1) × (3.2–) 3.3–4.0–4.5 (–4.6) μm, [Q = 1.00–1.08–1.20 (–1.26), Qm = 1.08 ± 0.06], globose to subglobose, ornamentation amyloid, 0.5–1.1 (–1.3) μm high, parallel and branched ridges and isolated warts, forming an incomplete or sometimes almost complete reticulum, some ridges connected by lower lines, plage distally to totally amyloid. Basidia [50/2/2] (18–) 20–23–27 (–28) × (5–) 6–8–9 μm, 2– or 4– spored, clavate, with refractive contents, sterigmata 1–5 μm long. Pleurocystidia (16–) 23–32–37 (–39) × (4–) 6–8–9 (–10) μm, subfusiform to subclavate, often with acute or obtuse apex, with a strongly refractive content at the middle or upper part. Lamella edge sterile. Cheilocystidia absent. Pileipellis an ixotrichoderm, 115–150 μm thick, hyphae 1.5– 2.2 µm broad, cylindrical to narrowly clavate with obtuse or slightly acute apices, sometimes with brown, granular intracellular pigments. Stipitipellis 160–185 μm thick, hyphae 1–3 µm broad, densely interwoven, brownish in 5 % KOH. Clamps absent in all parts of basidiomata.

Habitat:—Solitary in monsoon evergreen forest soil.

Other specimens examined: CHINA. Guangdong Province, Guangzhou City, Baiyun Mountain : 26 September 2020, L. H. Qiu, B20092602 ( GDGM 87009 ) ; 25 August 2016, L. H. Qiu, H16082533 ( GDGM 87011 ) ; 25 August 2016, L. H. Qiu, H16082525 ( GDGM 87012 ) .

Figures

FIGURE 2. Lactarius baiyunensis: a–d. fresh basidiomata (a–b. B21082143, holotype); e–f. Scanning electronic micrographs of basidiospores; g–h. Pleurocystidia; Scale bars: a-d = 1 cm; e = 1 μm. f–h = 10 μm. Photos by X.X. Huang and L.H. Qiu.

FIGURE 3. Lactarius baiyunensis (B21082143, holotype). a. Pleurocystidia and basidia; b. Basidia; c. Pleurocystidia; d. Pileipellis. Scale bars = 10 μm. Drawings by X.X. Huang.