Russula subterranea L. Fan & H.Y. Fu, 2025

Fu, Hao-Yu, Li, Ting & Fan, Li, 2025, Russula subterranea, a new sequestrate species of Russulaceae from China, Phytotaxa 695 (1), pp. 80-90 : 84

Russula subterranea L. Fan & H.Y. Fu sp. nov.

Mycobank:—MB856852

Diagnosis:—differs from the other sequestrate Russula by pileus surface and hymenophore brownish red to deep brown; basidiospores yellowish-brown to brown, globose to subglobose, ornamented with very densely isolated amyloid spines of 1–2 μm long; cystidioles sporadically, having conspicuous amorphous contents; pileocystidia absent.

Etymology:— subterranea , hypogeous, in reference to the habitat of this new species.

Holotype:— CHINA. Shanxi: Qinyuan County, Lingkongshan Mountain, in soil under Quercus sp. , 1 Nov 2017, collected by K. B. Huang ( BJTC FAN1153 ).

Description:— Basidiomata hypogeous, 1–2 × 2–3 cm, globose to subglobose. somewhat lobate, sessile. Pileipellis surface smooth to pruinose, brownish red (#cc9900) to deep brown (#cc6600). Hymenophore irregularly loculate, locules compacted, slightly labyrinthine, brownish red (#cc9900) to deep brown (#cc6600). Columella rudimentary to absent. Odor indistinct; taste a little sour. Lamellae arranged along both sides of the locules of Hymenophore, showing an irregular circular to labyrinthine pattern, reddish-brown (#cc9900) when fresh, brown (#cc6600) when dry.

Basidiospores globose to subglobose, 8.5–13(14) × 8.9–13.5(15) μm, Q = 1.0(0.93)–1.05, yellowish-brown to brown in water, slightly thick-walled, ornamented with amyloid, isolated spines of 1–2 μm long, spines dense, very broad at base, with a very narrow distance between the base of spines; hilar appendage usually conspicuous, 1–2.5 μm long; Basidia broadly clavate, broadly cylindrical, 17.7–33.4 × 6.9–12.8 μm, 2–4-spored, the sterigmata up to 3–9 μm long; cystidioles 25.2–40.2 × 5.5–10.4 μm, subclavate to clavate with rounded apices, with amorphorus contents, sporadically, arising in trama, not extending beyond basidia. Pleurocystidia 30–50 × 5–15 μm, fusoid or ventricose, apex obtuse, hyaline, unchanging in Sulfovanillin. Subhymenium 6–15 μm wide, composed of isodiametric cells 6–16 × 3–12 μm, cells 1–2 layered; hymenophoral trama textura intricata, hyphae hyaline, tortuous, 2.7–5.8 μm diam. Pileus context 33–56.3 μm thick, pseudoparenchymatous, composed of polygonal cells of 2–5 μm diam, mixed with a few of trichodermal hyphae; subpellis a textura intricata formed by short, cylindrical to fusiform hyphae 6.4–15 × 3–7.9 μm, hyphae more or less parallel; pileocystidia absent; pileipellis composed of loosely interwoven, 54.1–77.6 μm thick, hyaline hyphae 2–4 μm diam., sphaerocytes absent.

Habit, habitat and distribution:—hypogeous, gregarious, in mountain brown earth and cinnamon soil, found under Quercus sp. in Shanxi Province, China.

Other material examined:— CHINA. Shanxi Province: Qinyuan County, Lingkongshan Mountain, in soil under Quercus sp. , 1 Nov 2017, collected by K.B. Huang (BJTC FAN1154).