Russula clavulus B. Chen & J. F. Liang, 2021

Chen, Bin, Song, Jie, Zhang, Jin-Hua & Liang, Jun-Feng, 2021, Morphology and molecular phylogeny reveal two new species in Russula sect. Ingratae from China, Phytotaxa 525 (2), pp. 109-123 : 114

Russula clavulus B. Chen & J. F. Liang , sp. nov. ( Figs 2A–D , 3 , 4 )

MycoBank: MB 832290

Etymology: — clavulus (Latin) refers to basidiomata of this species look like a tack nailed to the ground.

Holotype: — CHINA, Yunnan Province, Kunming city, Yeya Lake , 28 July 2014, broadleaf forests, dominated by Quercus , 25°07′34″N; 102°51′42″E, 2126m asl., leg. LHJ14072805 ( RITF 3334 ).

Diagnosis: — Basidiomata medium-sized to large; pale to pale yellow pileus centre with small brown spots, margin with tuberculate striation up to the 1/3 of the radius; lamellae with some small pale yellow spots; white to yellowish spore print; subglobose to broadly ellipsoid spores with short or long ridges; hymenial cystidia on lamellae sides that are mainly subclavate or fusiform and apically often obtuse or acute; pileocystidia near the pileus margin always long and one-celled, turning light purple in SV.

Description: — Basidiomata medium-sized to large, 70–92 mm in diam., broadly convex to applanate with a slightly depressed centre; margin incurved, rarely cracked, tuberculate striation up to the 1/3 of the radius; cuticle smooth, glabrous, viscous when humid, not peeling readily; pale (2A2) to pale yellow (4A3) with small brown spots in the cap centre; margin white (1A1), buttercup yellow (4A5) in some part. Lamellae 2–4 mm deep, relatively dense, adnate to slightly free, white (1A1) to pale (2A2), with some small pale yellow (4A3) spots; lamellulae rarely or absent; occasionally forked and slightly interveined near the stipe. Stipe 80–95× 10–25 mm, central, subcylindrical to cylindrical, slightly expanded towards the base, surface dry, rugulose longitudinally, white to whitish with or brownish spot, pithy and hollow. Context 2–3 mm thick at pileus centre, white to cream, unchanging when bruised; taste mild to slightly acrid; odour indistinct. Spore print white to yellowish.

Spores (5.6–)7.0–7.8–8.6(–9.0) × (5.4–)6.5–7.2–8.0(–8.3) μm, Q=(1.0–)1.03–1.09–1.14(–1.24), subglobose to broadly ellipsoid; ornamentation of large, distant to moderately distant (3–6 in a 3 μm diam. circle) amyloid warts, up to 1.6 μm high, isolated or occasionally fused (0–2 fusions in the circle), often forming short or long ridges [1– 3 fusions in the circle], line connections absent; suprahilar spot indistinct. Basidia (30.6–)43.6–48.8–54(–57.7) × (9.6–)11.5–12.9–14.2(–15.5) μm, mostly 4-spored, some 2- and 3-spored, subclavate to clavate, some with granulose contents, rarely containing oil droplets; basidiola clavate, ca.10–18 μm wide. Hymenial cystidia on lamellae sides moderately numerous, ca. 1000/mm 2, (45.2–)48–53.4–58.8(–65) × (5.8–)7.2–10–13(–16) μm, subclavate or fusiform, apically often obtuse or acute, sometimes moniliform, occasionally with 2–8 μm long appendage, thin-walled; contents abundant granulose or flocculent, turning to blackish-grey in SV. Hymenial cystidia on lamellae edges often longer and narrower, (47–)52.5–58.8–65.2(–75) × (5.4–)6–7.8–9.6(–13.7) μm, narrowly clavate to subcylindrical, apically obtuse or mucronate, sometimes with 2–5 μm long appendage, contents granulose, turning to blackish-grey in SV. Marginal cells (9.3–)11.8–15–18.3(–21.5) × (4–)4.8–5.6–6.5(–7.3) μm, clavate or subcylindrical, sometimes flexuous. Pileipellis orthochromatic in Cresyl blue, not sharply delimited from the underlying context, 185–255 μm deep, two–layered; suprapellis 65–75 μm deep, composed of ascending or erect hyphae terminations; subpellis 120–180 μm deep, composed of strongly gelatinised horizontally narrow hyphae. Hyphal terminations near the pileus margin rarely branched, sometimes flexuous, thin–walled; terminal cells (12–)13.7–24.7–35.7(–60.7) × (2.5–)3.2–4.3–5.3(–7) μm, mainly clavate, occasionally subcylindrical, apically obtuse; subterminal cells often narrower, ca. 2–5 μm wide, usually unbranched. Hyphal terminations near the pileus centre less flexuous; shorter terminal cells (8.9–)13.4–20.6– 27.8(–37.6) × (2.7–)3.6–4.6–5.6(–9.3) μm, lageniform or subcylindrical, apically obtuse or occasionally attenuated; subterminal cells often shorter, usually unbranched, ca. 2.5–6 μm wide. Pileocystidia near the pileus margin always long one-celled, (38.7–)76–129–182(–200) × (3.9–)4.4–5.8–7(–9) μm, cylindrical to clavate, apically usually obtuse or occasionally mucronate, contents dense granulose, turning to brownish–black in SV. Pileocystidia near the pileus centre often shorter, similar in shape and contents, (38.2–)59–74–89(–100) × (5–)5.5–6.4–7.3(–9) μm, contents turning to brownish–black in SV. Cystidioid hyphae in subpellis and context, contents granulose. Oleiferous hyphae in context, with oil contents.

Additional specimens examined: — CHINA, Guizhou Province, Zunyi city, Wuchuan County, Fenshui Town , Jinhua Village , 22 September 2014, 28°53′29″ N, 107°59′7″ E, 1072m asl., leg. LHJ14092226 ( RITF 3300 ); ibid., Southwest Guizhou Buyi and Miao Autonomous Prefecture , Wangmo County, Wangmo Nature Reserve , 23 August 2013, 25°12′34″N; 106°15′48″E, 1272m asl., leg. Wu 481 ( RITF 3216 ) ; Yunnan Province, Kunming city, Qiongzhu Temple , 28 July 2012, 25°03′55″N; 102°37′28″E, 2153m asl., leg. R5 ( RITF 3204 ) .

Figures

FIGURE 2. Russula clavulus (RITF 3334, Holotype).A–B Basidiomata, Scale bars= 20mm.C–D Spores in SEM (JSM-6510LV); Russula multilamellula (RITF 3346, Holotype). E–F Basidiomata, Scale bars = 15 mm. G–H Spores in SEM (JSM-6510LV).

FIGURE 3. Russula clavulus (RITF 3334, Holotype). Microscopic features of the hymenium. A Basidia. B Basidiola. C Marginal cells. D Hymenial cystidia on lamellae sides. E Hymenial cystidia on lamellae edges. Scale bars = 10 μm.

FIGURE 4. Russula clavulus (RITF 3334, Holotype). Microscopic features of the pileipellis. A Pileocystidia near the pileus margin. B Pileocystidia near the pileus centre. C Hyphal terminations near the pileus margin. D Hyphal terminations near the pileus centre. Scale bars = 10 μm.