Russula pseudosenecis A.Ghosh, D.Chakr., K.Das & Buyck, 2022

Ghosh, Aniket, Buyck, Bart, Das, Kanad, Bera, Ishika & Chakraborty, Dyutiparna, 2022, Two new Asian species of Russula sect. Ingratae with unique basidiospore features for subg. Heterophyllidiae, European Journal of Taxonomy 847, pp. 104-120 : 112-115

Russula pseudosenecis A.Ghosh, D.Chakr., K.Das & Buyck sp. nov.

MycoBank: MB842137

Figs 4B – 6

Diagnosis

Russula pseudosenecis sp. nov. differs mainly from R. senecis Imai by its mild taste, paler pileus colour, chalky white gills when young, strongly amyloid suprahilar spot on the basidiospores and its association with Shorea robusta C.F.Gaertn. from the tropical tree family Dipterocarpaceae Blume.

Etymology

Referring to it being a look-alike of R. senecis , originally described from Japan.

Material examined

Holotype INDIA • West Bengal, Bankura district, Joypur forest ; 23°03′11″ N, 87°25′49″ E; alt. 74 m a.s.l.; in tropical forest under Shorea robusta ; 30 Aug. 2020; A. Ghosh AG 20-062; GenBank: OL461233 (ITS); CAL[1858].

Additional material

INDIA • West Bengal, Paschim Medinipur district, Chandra ; 22°21′01″ N, 87°02′00″ E; alt. 90 m a.s.l.; in tropical forest under Shorea robusta ; 12 Aug. 2020; A. Ghosh AG 20-019; CAL[1895] • Jhargram district, Tuluha ; 22°19′44″ N, 87°02′39″ E; alt. 80 m a.s.l.; in tropical forest under Shorea robusta ; 11 Aug. 2021; A. G hosh AG 21-073; GenBank: OL461234 ( ITS); CAL[1859] • Uttar Dinajpur, Kaliyaganj, Dhamja forest ; 25°34′56″ N, 88°20′16″ E; alt. 80 m a.s.l.; in tropical forest under Shorea robusta ; 10 Oct. 2021; D. Chakraborty, RGJ -20-04; CAL[1896] • Jharkhand, Rajmahal hills, Pakur district, Hiranpur block , Talpahari to Tugutola forest area; 24º37′02.6″ N, 87º40′45.2″ E; alt. 94 m a.s.l.; in tropical forest under Shorea robusta ; 26 Aug. 2021; A. Ghosh AG 21-14 (JH); CAL[1897] • ibid., Sahibganj district, Borio block, Dhogada , Paharia burial ground forest; 25°02′23.7″ N, 87°39′35.8″ E; alt. 110 m a.s.l.; in tropical forest under Shorea robusta ; 17 Sep. 2022; A. Ghosh AGJH-033; CAL [1898] .

Description

Pileus small to medium-sized, 15–55 mm in diameter, convex, planoconvex to applanate with depressed center; margin decurved to plane, entire, strongly tuberculate-striate; surface viscid and glutinous when moist, dull upon drying, quickly cracked, easily peeled off ⅓ rd to ½ th towards center with maturity, pale yellow, light yellow to grayish yellow (4A–B3–5) or yellowish brown, light brown to golden brown (5D–E5–8), centrally dark brown (6–7E6–8) with maturity or age. Pileus context up to 5 mm thick at the disc, compact, firm, chalky white (1–2A1), unchanging after bruising or on exposure. Lamellaeadnate to adnexed, close to crowded (12–15/cm at pileus margin), up to 4 mm thick, chalky white (1–2A1), entire, forked at the stipe apex, middle and near the margin, unchanging after bruising or on exposure; edges punctuated with brownish orange (6C5–7) or light brown (6D5–7), entire; lamellulae rare. Stipe 20–45 × 9–15 mm, firm, brittle, cylindrical to subclavate, centrally attached; surface dry, longitudinally striate, pale to light yellow (4A3–4) or grayish yellow (4B5–6) with light brown (6D5–7) to brown (6D6–7) tinges, unchanging when bruised or on exposure; turning salmon pink (6A4) and deep to dark turquoise (24E–F7–8) in FeSO 4 and guaiacol, respectively. Stipe context pale yellow to light yellow (5A3–5), chambered, unchanging when bruised or on exposure; turning salmon pink (6A4) and deep to dark turquoise (24E–F7–8) in FeSO 4 and guaiacol, respectively. Odor indistinctive. Taste mild. Spore print not observed.

Basidiospores globose to subglobose, (7.1–)7.5–7.8–8.3(–8.3) × (6.7–)7.0–7.4–7.8(–8.3) μm, Q = (1.02–)1.03–1.06–1.09(–1.13); ornamentation amyloid, composed of up to 2.2 μm high wings running over more or less long distances on the spore surface or even nearly encircling the spores, mixed with a dense, low network of short, laterally flattened, blunt ridges and warts forming an incomplete network, intermixed with crowded, isolated warts and large spines (up to 1.8 μm high), some partly connected; suprahilar spot strongly amyloid, uplifted and distinct; apiculi up to 2.5 μm long. Basidia (40–)46–50–54(–57) × (7–)9– 11–13(–14) μm, 4-spored, subclavate to clavate, tapered at the base; sterigmata up to 7 μm long. Hymenial cystidia on lamellae sides (50–)62.4–75.1–87.7(–100) × (6–)6.4–7.8–9.1(–11) μm, abundant, cylindrical to lanceolate with obtuse-rounded, mucronate to capitate or subcapitate, appendiculate to lageniform or moniliform apex, emergent up to 60 μm beyond the basidiole tips, few deeply embedded; content dense, finely crystalline with refractive granular bodies, turning gray-black with sulfovanillin. Lamellae edges fertile with basidia and cystidia. Hymenial cystidia on lamellae edges (34–)37–46.5–56(–60) × 5–6–7(–8) μm, cylindrical to lanceolate with obtuse-rounded, subcapitate to appendiculate apex; content dense, finely crystalline with refractive granular bodies, turning gray-black with sulfovanillin. Marginal cells not differentiated. Subhymenium layer up to 20 μm thick, pseudoparenchymatous. Hymenophoral trama composed mainly of large nests of sphaerocytes and few hyphal elements. Pileipellis orthochromatic in Cresyl Blue, sharply delimited from the underlying sphaerocytes of the context, 120–150 μm thick, two-layered; subpellis 60–75 μm deep, composed of more or less dense, horizontally oriented hyphae and dispersed pileocystidia that originate in the subpellis and not implanted on the top of the suprapellis; suprapellis pseudoparenchymatous, an ixo-palisade, 60–75 μm thick, mainly composed of ascending to erect, densely septate, hyphal terminations composed of inflated or cylindrical cells. Acidoresistant incrustations absent. Hyphal terminations near the pileus margin thin-walled, composed of chains of 3–5 cells; terminal cells (9–)10–13.8–17.7(–26) × (4.5–)6–7.7–9.2(–11) μm, mainly clavate to subglobose, rarely cylindrical, with rounded apex; subterminal cells inflated or cylindrical. Hyphal terminations near the pileus center also thin walled, rarely branched at the subterminal cells; terminal cells slightly longer and less wide, measuring (9–)9.9–15.3–20.6(–25) × (3–)3.5–4.9–6.3(–7) μm, mainly cylindrical or clavate; subterminal cells mainly cylindrical or inflated. Pileocystidia originating from the subpellis only, not as terminal cells in the suprapellis, single-celled, long, flexuous, thin-walled, (50–)53–86.9–121(–150) × (2.5–)3–4.2–5.3(–6) μm, mainly cylindrical, apically mainly obtuse-rounded or mucronate; contents finely crystalline with refractive granular bodies, turning gray-black in sulfovanillin. Pileocystidia in the pileus center slightly shorter (41.6–)42.6–67.6–92.6(–132) × (2–)2.8–4.3–5.8(–5) μm, sometimes with lateral projections, apically obtuse-rounded, otherwise identical. Oleiferous hyphae present. Clamp connections absent from all tissues.

Figures

Fig. 4. Basidiospores in Melzer’s reagent. A. Basidiospores of Russula indosenecis A.Ghosh, D.Chakr., K.Das & Buyck sp. nov. B. Basidiospores of Russula pseudosenecis A.Ghosh, D.Chakr., K.Das & Buyck sp. nov.

Fig. 6. Russula pseudosenecis A.Ghosh, D.Chakr., K.Das & Buyck sp. nov. (from holotype, AG 20-062). A. Basidiospores. B. Basidia. C. Hymenial cystidia near the lamellae edges. D. Hymenial cystidia on the lamellae sides. E. Hyphal terminations in the pileus center. G. Pileocystidia in the pileus center. F. Hyphal terminations near the pileus margin. H. Pileocystidia near the pileus margin. Scale bars: A–H = 10 μm.