Russula buyckii K. Acharya, S. Paloi & A.K. Dutta, 2016

Paloi, Soumitra, Dutta, Arun Kumar, Pradhan, Prakash, Roy, Anirban & Acharya, Krishnendu, 2016, Russula buyckii, a new species of Russula subgenus Incrustatula from Eastern Himalaya, India, Phytotaxa 252 (2), pp. 123-130 : 124-127

Russula buyckii K. Acharya, S. Paloi & A.K. Dutta , sp. nov., Figures 1 & 2

MycoBank MB 814987

Etymology:—Named after Bart Buyck, for the contribution that he has made to further our understanding of the genus Russula .

Diagnosis:—Entirely white basidiocarp, with a small (20–26 mm), convex (when young) to broadly convex (at maturity) pileus, with equal gills, white spore print, mild taste; pileipellis with 4.5‒6.5 μm broad primordial hyphae, measuring 64‒155 × 4.5‒6.5 μm near cap margin and 68‒100 × 4‒5.4 μm in the center; basidiospores broadly ellipsoid, 6.2‒7.05‒7.5(‒8.1) × 5.4‒6.1‒6.5(‒7.2) μm, Q = 1.1‒1.15‒1.2 with isolated spines and a distinct amyloid suprahilar plage; cystidia clavate with mucronate to moniliform apex, present on gill sides (37‒45 × 7.2‒9.8 μm) and edges (44‒58 × 7‒12) μm; stipitipellis with cylindrical to subclavate caulocystidia (19.5‒32 μm long).

Holotype:— INDIA. West Bengal: Darjeeling district, 7 th Mile, near Gurdum , elev. 2007 m, 26 June 2012, Prakash

Pradhan (CUH AM277, holotype).

Description:— Basidiomata small. Pileus 20‒26 mm diam., convex when young, becoming broadly convex to planoconvex with depressed center when mature; surface slightly viscid when wet with sulcate margin; entirely white

(1A1), turns ochraceous during handling, green (26A7, 26B8) to vivid green (26A8) with KOH, no colour change with

FeSO 4; context upto 1 mm thick towards center, gradually thinner towards margin, white (1A1), unchanging colour on exposure, orange (6B8), brownish orange (6C8) to reddish orange (7A8) with phenol. Lamellae 3‒3.5 mm broad,

adnexed, regular, white (1A1), unchanging after bruising, orange (6B8), brownish orange (6C8) to reddish orange

(7A8) with phenol, light brown (7D7-8) to brown (7E8) with FeSO 4 and Guaicol, edge even, concolourous; lamellulae absent. Stipe 16‒19 × 2.5‒4 mm, central, cylindrical with tapering towards apex, curved towards center, white (1A1);

surface semi moist, reddish orange (7 A8 ) to brownish orange (7 C8 ) with FeSO 4, reddish orange (7 A8 , 7 B8 ) to brownish orange (7 C8 ) with Guaicol and reddish orange (7 A8 , 7 B8 ) with Phenol ; context hollow, white, unchanging after bruising, violet brown (10 E8, 10 F8 ) with sulfovanilin (never bright red). Taste mild and odor indistinctive. Spore print white .

Basidiospores 6.2‒7.05‒7.5(‒8.1) × 5.4‒6.1‒6.5(‒7.2) μm, Q = 1.1‒1.15‒1.2, broadly ellipsoid, ornamentation amyloid, composed of isolated warts; high warts (0.9‒1.3 μm) spinoid with rounded apices, rarely fused with each other (but, no connectives or veins in between); some low conical warts (0.35‒0.4 μm) between high warts; suprahilar plage distinct, 1.4‒1.6 μm long, amyloid. Basidia (23‒)26‒36(‒38) × (8‒)9‒11(‒14) μm, clavate to subclavate, thinwalled, oil granules present when viewed with KOH, 4‒spored; sterigmata 4.5‒7 × 2‒3 μm. Subhymenium cellular; cells subglobose to ellipsoid. Lamellar trama mainly composed of large sphaerocytes. Hymenial cystidia 37‒40(‒ 45) × 5‒7(‒10) μm on gill sides, near the gill edge (44‒)50‒57(‒58) × (7‒)8‒10.5(‒12) μm, clavate with mucronate to moniliform apex, with heteromorphous contents that are restricted to the central or upper part of the cystidium, oil granule often present when viewed with KOH, thin-walled. Pilieipellis orthochromatic in cresyl blue, sharply delimited from underlying sphaerocytes of the context, up to 100‒143 μm deep, vaguely divided in a 35.8‒53.7 μm deep suprapellis of gelatinized tissue of ascending hyphal terminations, 3.5‒5.5 μm wide towards the context. Hyphal extremities of the suprapellis short, with terminal cells measuring near cap margin 3.5‒5.5(‒7) μm broad and in the cap center 4.5‒5.5(‒7) μm broad, 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 4.5‒5.4(‒6.5) μm broad cylindrical cells, in Congo red optically active, obtuse and measure (64‒)68‒90(‒155) × 4.5‒5.4(‒6.5) μm near cap margin and (68‒)75‒86(‒100) × 4‒4.6(‒5.4) 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, semi-gelatinous hyphae and caulocystidia, incrustations absent; hyphal ends 3.5‒4(‒5) μm wide, septate; caulocystidia measuring ca. 19.5‒32 μm long, cylindrical to subclavate, hyaline, thin-walled. Stipe trama composed of connective hyphae and nested sphaerocytes; sphaerocytes measuring ca. (22‒)32‒35(‒37) × (17‒)28‒29.5(‒35) μm diam., hyaline. Clamp connections absent in all tissues.

Habitat and distribution:—Growing solitary or in a group, under Castanopsis sp. (Family- Fagaceae ) tree among the mosses, West Bengal, India.

Phylogenetic analysis: —Based on the nrITS sequence data, the phylogenetic relationships of the newly described species was inferred from MCMC analyses. Sequencing products of the newly described species ranged 588 nucleotides. All sequences were aligned and the ends trimmed to create a dataset of 650 nucleotides. Bayesian analyses reached a standard deviation of split frequencies of 0.004 after 106 generations. The initial 25% trees recovered were excluded as the burn-in and the remaining trees obtained were then used to estimate the posterior probabilities of the group. The phylogenetic tree is shown in Figure 3 . 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 (-ln L = 1970.8770). Parsimony analyses produced four most parsimonious trees among which Tree # 1 (length = 284), C.I. = 0.598425, R.I. = 0.794355, composite index = 0.509058 (0.475362), did not differ significantly in topology from those recovered in the Bayesian and ML analyses. Along with accession numbers of newly generated nrITS sequence, as well as those pulled from GenBank database, data obtained from Bayesian (PPs), ML and MP analyses (bootstrap percentage) and are indicated in Figure 3 .

Figures

FIGURE 1. Russula buyckii (CUH AM277). a–b. Fresh basidiomata in the field; c–d. Scanning Electron Micrograph of basidiospore. Scale Bars: a–b = 10 mm.

FIGURE 2. Microscopic features of Russula buyckii (CUH AM277, holotype). a. Basidiospores as seen in Melzer’s reagent; b. Basidia; c. Hymenial cystidia (near gill sides) as observed in Congo Red; d. Primordial hyphae at pileus surface; e. Hyphal terminations near the pileus margin; f. Hyphal terminations of the pileus center; Scale Bars: a‒f = 5 μm. (Drawing by A.K. Dutta).

FIGURE 3. Consensus phylogram (50% majority rule) obtained from MCMC analysis of one million generations from a Bayesian analysis of the nrDNA ITS sequence alignment. Values to the left of the “/” are MLBS support, and those to the right indicate Bayesian posterior probabilities (PP) of that clade. PP values>0.90 and MLBS values ≥70% are shown. MPBS values ≥70% are indicated as colour-coded thickened lines and the scale bar represents the expected changes per site. The new species is highlighted in boldface on the phylogenetic tree. Corresponding subgenus and subsections are indicated to the right of the tree. Categorizations of Russula species within the tree follow the classification of Sarnari (1998).