Russula hookeri S. Paloi, A.K. Dutta & K. Acharya, 2015

Paloi, Soumitra, Dutta, Arun Kumar & Acharya, Krishnendu, 2015, A new species of Russula (Russulales) from Eastern Himalaya, India, Phytotaxa 234 (3), pp. 255-262 : 257-260

Russula hookeri S. Paloi, A.K. Dutta & K. Acharya sp. nov., Figures 2 & 3

MycoBank MB 812298

Diagnosis:—Small to medium-sized (20–35 mm), convex (when young) to uplifted (with maturity), greyish red to greyish rose pileus margin with brownish red center, white lamellae with one lamellula, greyish red to greyish ruby stipe, white spore print, mild taste, presence of 4‒5(‒5.5) μm broad primordial hyphae in the pileipellis, measuring 78‒138 × 4‒5.5 μm near cap margin and 79‒107 × 3.9‒4.4 μm in the center; smaller subglobose to broadly ellipsoid (5.4‒7.2 × 4.5‒6.4 μm; Q=1.14) basidiospores with a distinct amyloid suprahilar plage, hyaline, clavate cystidia on gill sides (51–62 × 11.5–14.5 μm) and edges (34–43 × 7.5–10 μm), and presence of cylindrical to subclavate caulocystidia (17–27 μm long).

Type:— INDIA. West Bengal: Darjeeling district, near Hooker road, 27°05′14″N, 88°26′35″S, elev. 2084 m, 16 July 2012, Arun Kumar Dutta (CUH AM275, holotype).

Pileus 20‒35 mm diam., convex when young, becoming uplifted (infundibuliform) with maturity, centre often umbonate, later depressed; surface slightly viscid when wet with striate margin; greyish red (10C5) when young, brownish red (10D6) in the centre with maturity, margin greyish red (10C5) to greyish rose (12B4), no colour change with KOH and NH 4 OH, orange with FeSO 4; context 0.2‒0.3 mm thick towards the margin, white, unchanging colour on exposure, no colour change with KOH and NH 4 OH, yellow-orange with FeSO 4 and cinnamon with phenol. Lamellae 4‒5 mm broad, adnexed, regular, white (1A1), unchanging after bruising, no colour change with KOH and FeSO 4, sienna with phenol and rusty tawny with Guaicol; edge even, concolourous; lamellulae one. Stipe 10‒25 × 3‒5 mm, equal to tapering towards base, slight curved towards center, greyish red (10C5) to greyish ruby (12C6); surface semi moist, no colour change with KOH, FeSO 4, Guaicol and Phenol; context hollow, white, unchanging after bruising, unchanging with FeSO 4, guaiac and Phenol, undistinctive with sulfovanilin (never bright red). Taste mild and odor indistinctive. Spore print white.

Basidiospores (5.4‒)6‒6.1‒6.3(‒7.2) × 4.5‒5.37‒5.7(‒6.4) μm, Q=1.1‒1.14‒1.2, subglobose to broadly ellipsoid; ornamentation amyloid, composed of isolated warts; high warts (0.6‒0.7 μm) spinoid with rounded apices, rarely fused with each other (but, no connectives or veins in between); some low conical warts (0.4‒0.5 μm) between high warts; suprahilar plage distinct, 1.4‒1.8 μm long, amyloid. Basidia (20‒)23‒25.7‒27(‒33) × 7‒8.0‒8.9‒(10.5) μm, subclavate, thin-walled, often oil granules present when viewed with KOH, 4-spored; sterigmata 3.5‒7 × 0.9‒1.3 μm. Subhymenium cellular; cells subglobose to ellipsoid, 18‒25(‒32) × 14‒23(‒15) μm. Lamellar trama mainly composed of large sphaerocytes. Hymenial cystidia crowded, measuring ca. 51‒57(‒64) × 11.5‒13(‒14.5) μm on gill sides, near the gill edge ca. (34‒)38‒40(‒43) × 7.5‒9(‒10) μm, clavate, hyaline, thin-walled. Pilieipellis orthochromatic in cresyl blue, sharply delimited from underlying sphaerocytes of the context, up to 78‒111(‒133) μm deep, vaguely divided in a (32‒)39.5‒43(54) μm deep suprapellis of gelatinized tissue of ascending hyphal terminations, 3‒3.5(‒4.5) μm wide towards the context. Hyphal extremities of the suprapellis short, with terminal cells measuring near cap margin 15‒38(‒42) × 4‒8.5 μm and in the cap center 20‒24(‒32) × 4‒4.5(‒10) μm, cylindrical, obtuse at the tip; subapical cells branched or not, often with lateral branches or nodules. Primordial hyphae comparatively longer than the other extremities and often protruding or repent on the cap surface, occurring mostly singly or with a few clustered together, composed of 3‒5(‒5.5) μm broad cylindrical cells, in Congo red optically empty, obtuse and measure 78‒ 138 × 4‒5.5 μm near cap margin and 79‒107 × 3.9‒4.4 μm in the center, thin- to slightly thick-walled (<1 μm); incrustation present, negative in sulfovanilin. Cystidioid hyphae in subpellis and trama absent. Stipitipellis a palisade, suprapellis of repent to erect, non-gelatinous, often branched hyphae and caulocystidia; hyphal ends 3.5–5 μm wide, septate; caulocystidia measuring ca. (17‒)19‒25(‒27) μm long, cylindrical to subclavate, hyaline, thin-walled. Stipe trama composed of connective hyphae and nested sphaerocytes; sphaerocytes measuring ca. 18‒32 × 14‒25 μm diam., hyaline. Clamp connections absent in all tissues.

Habit/Distribution:—Growing solitary to in a group of two, under Castanopsis sp. tree among the mosses of the family Polytricaceae , West Bengal, India.

Etymology:—The epithet “ hookeri ” honours the mycologist Joseph Dalton Hooker.

Phylogenetic analysis: —Phylogenetic analysis was performed on an ITS dataset representing 19 Russula species (23 sequences), distributed over three well-accepted subgenera: subgen. Compactae (4 sequences), Incrustatula (14 sequences) and Russula (5 sequences). Three species belonging to the subgen. Compactae [ R. albonigra (Krombh.) Fr. , R. compacta Frost and R. nigricans Fr. ] were used as outgroup. All sequences were aligned and the ends trimmed to create a dataset of 608 nucleotides that included 403 positions in the final dataset.

Each of the ML analysis iterations recovered a single tree, the likelihood values of which did not differ significantly. We have selected the topology resulting from the first iteration to present here ( Figure 1 ; -ln L = 1855.2535). In MP analyses, Tree 1 out of 3 most parsimonious trees (length = 258; C.I. = 0.594828, R.I. = 0.758974) displayed overall similar topology with the phylogram recovered in the ML analyses. Bayesian analyses reached a standard deviation of split frequencies of 0.003 after one million generations. Figure 1 depicts the ML tree and highlights significant branch support recovered by ML, MP bootstrapping as well as posterior probabilities (PP) derived from the Bayesian majority-rule consensus tree (ML-BS and MP-BS: ≥ 70%, PP: ≥ 0.95).

Figure 1 revealed a monophyletic clade comprised of taxa like Russula azurea Bres. , R. corallina Burl. , R. lilacea , R. subtilis Burl. together with the newly described R. hookeri with moderate to significant support (MLBS=78%, MPBS=80%, PP=1.00). Morphologically all these taxa possess a brightly coloured pileus, mild taste, white spore print, incrusted primordial hyphae in the pileipellis, no dermatocystidia, and they never turn bright red with sulfovanilin in dried specimens. All of these features suggest that these taxa belong to the subsect. Lilaceinae of sect. Lilaceinae in subgen. Incrustatula ( Sarnari 1998). The nrDNA ITS sequence of the newly described R. hookeri from India clusters together with sequences of two Chinese collections with strong support (MLBS=100%, MPBS=97%, PP = 1.0) which suggests that these three collections are conspecific.

Russula lepidicolor Romagn. , a species placed by Sarnari (1998) within subsect. Roseinae Singer ex Sarnari of the sect. Lilaceinae, clusters with two sequences of R. velenovskyi Melzer & Zvára (subgen. Russula ), and members of the subsect. Integroidinae ( R. amara Kučera , R. claroflava Grove and R. vinosa Lindblad ) without support. Morphologically, members of the subsect. Roseinae gives a persistent bright red coloured reaction in dried fruit bodies with sulfovanilin which distinguishes them from the subsect. Lilaceinae ( Sarnari 1998). Russula risigallina (Batsch) Sacc. , member of the subsect. Chamaeleontinae Singer, clusters with two included taxa (viz. R. amethystina and R. turci Bres. ) of the subsect. Amethystinae (characterized by a yellow to rarely ochre spore print; Sarnari 1998) with relatively strong support (MLBS=95%, MPBS=90%, PP = 1.0).

Figures

FIGURE 1. Maximum likelihood tree (-lnL = 1855.2535) generated using a GTR+I+G model of nucleotide evolution. Numbers to the left of / are MP bootstrap support (MPBS), and those to the right indicate the Maximum likelihood bootstrap (MLBS) support (in bold). MLBS and MPBS values ≥ 70% are shown. Bayesian posterior probabilities (PP)> 0.95 are indicated as black coloured thickened lines and the scale bar represents the expected changes per site. Russula hookeri is placed in bold font to highlight its phylogenetic position in the tree. Categorizations of Russula species within the tree follow classification of Sarnari (1998).

FIGURE 2. A–B. Russula hookeri (CUH AM275). A. Fresh basidiomata in the field; B. Scanning Electron Micrograph of basidiospore. Scale Bars: A=10 mm; B=1 μm.

FIGURE 3. A–F. Russula hookeri (holotype). A. Basidiospores as seen in Melzer’s reagent; B. Basidia; C. Hymenial cystidia (near gill edge) as observed in Congo Red; D. Hyphal terminations near the pileus margin; E. Hyphal terminations of the pileus center; F. Primordial hyphae at pileus surface. Scale Bars: A=5 μm; B–F=10 μm.