Russula sp.

Wisitrassameewong, Komsit, Park, Myung Soo, Lee, Hyun, Ghosh, Aniket, Das, Kanad, Buyck, Bart, Looney, Brian P., Cabon, Miroslav, Adamcik, Slavomir, Kim, Changmu, Kim, Chang Sun & Lim, Young Woon, 2020, Taxonomic revision of Russula subsection Amoeninae from South Korea, MycoKeys 75, pp. 1-29 : 1

Russula sp. Figs 3F, G , 4E, F , 7

Diagnosis.

Pileus medium-sized, 60 mm diam., applanate with deeply depressed center, margin distinctly striate, crenulate, radially cracking; cuticle dry, viscid when moist, pruinose, peeling to 1/2 of the pileus radius, color greyish violet (18E5-E6), with dark violet (18F4-F6) patches, towards margin violet grey (18D2) to dull violet (18D3). Lamellae 3 mm deep, adnate, dense, pale cream; lamellulae rare, forked near the stipe; edge smooth and concolorous. Stipe 55 × 8-10 mm, centrally attached, tapering downwards base, surface dry, longitudinally-striated, white and flushed with purple. Context 2 mm thick at half of the pileus radius, white, unchanging; taste and odor not recorded. Spore print cream white.

Basidiospores (n = 20, 1, 1) (6.4-)6.5-6.8-7(-7.2) × (5.5-)5.6-5.9-6.2(-6.5) µm, Q = (1.08-)1.1-1.14-1.19(-1.24), subglobose to broadly ellipsoid, ornamentation of thin to moderately thick, 0.8-1.4 µm high ridges forming an incomplete reticulum (2-6 in a 3 µm circle), isolated warts rare (0-2 in a 3 µm circle), suprahilar spot not amyloid, small. Basidia (32-)34-36.2-38.5(-40) × (9-)9.5-10.5-11(-11.5) µm, 4-spored, clavate. Basidiola (24-)25.8-31-35(-42.5) × (8.3-)8.9-9.9-10.8(-11.4) µm, narrowly clavate, with guttate or granular contents. Hymenial cystidia on lamellae sides widely dispersed to dispersed, 100-500 per mm2, (63)66.5-79-91.5(-109) × (10.5-)12.5-14.5-16.5(-18) µm, narrowly fusiform or lageniform, originating from subhymenium and emergent beyond basidia, apically acute or obtuse but narrowed, thick-walled (walls up to 0.9 µm), contents optically empty, negative in sulfovanillin. Lamellar edge with dispersed basidia, true gloeocystidia (with differentiated contents) absent; marginal cells very abundant, resembling terminal cells in the pileus, narrowly lageniform or subulate (36.5-)42.5-49.6-56.5(-70.1) × (5-)5.5-6.3-7(-7.5) µm, narrowly lageniform or subulate, apically acute; narrowly clavate to clavate with optuse apex, (11.5-)14.5-17.8-21.2(-23.2) × (4-)5.2-6.2-7(-7.5) µm. Pileipellis orthochromatic in Cresyl blue, sharply delimited from the underlying context, 250-400 µm thick, with gelatinous matter, cystidoid hyphae prevailing, shorter cylindrical terminal hyphae present, parallel or repent scattered, pileocystidia absent, with a well-defined, gelatinized, 70-120 µm thick suprapellis of ascending or erect hyphal terminations forming a trichoderm, subpellis 230-350 µm thick, dense, horizontally oriented, gelatinized and branched cylindrical hyphae; acid-resistant incrustrations absent. Hyphal terminations near the pileus margin unbranched, usually only slightly flexuous, either long and attenuated or subcylindrical, short and obtuse; the attenuated ones more frequent, with terminal cells (45.0-)60.0-72.6-85.0(-96.5) × (3.5-)4.5-5.1-6.0(-6.5) µm, subulate, apically acute, thin-walled, shorter ones with terminal cells (18-)20.5-28.7-37.0(-48.0) × (3.0-)3.5-4.4-5.0(-6.0) µm, cylindrical or subcylindrical, apically obtuse but often constricted, thin walled; followed by (0-)1-2(-3) unbranched shorter and equally wide cells. Hyphal termination near the pileus center similar but shorter and narrower, attenuated longer ones with terminal cells (38.5-)43.5-53.4-63.0(-73.0) × (2.5-)3-3.5-4.0(-4.5) µm; shorter cylindrical ones with terminal cells (11.5-)13.5-16.4-19.0(-22.0) × (3.0-)3.5-4.1-4.5(-5.5) µm. Pileocystidia absent. Cystidioid or oleipherous hyphae in subpellis or context absent.

Ecology.

solitary on soil in deciduous forest, near Quercus mongolica .

Material examined.

South Korea. Incheon-si, Ongjin-gun, Jangbongdo islands, 72 m elev., 37°31'55"N, 126°21'10"E, Jae Young Park, Nam Kyu Kim, Suldbold Jargalmaa, 26 July 2016, SFC20160726-13 (Holotype, SFC!).

Comments.

This species is morphologically similar to R. mukteshwarica , but phylogenetically close to R. pseudoamoenicolor and R. pauriensis . Russula mukteshwarica and R. pauriensis differ from Russula sp. in the greenish yellow region at the pileus center, which is present in the first two species but absent in the latter ( Das et al. 2005, 2017). Russula pseudoamoenicolor has a discolorous lamella edge ( Hyde et al. 2016), whereas Russula sp. has a concolorous lamellae edge. Russula sp. has a purple pileus similar to that of R. violeipes ; however, spore ornamentation height (up to 0.7 µm) and pleurocystidia size (80-115 × 12-15 µm) distinguishes Russula sp. from R. violeipes ( Kränzlin 2005).

Figures

Figure 3. Basidiomes of Korean Amoeninae from this study. A, B Russula bella (A-SFC 20170802 - 03, B-SFC 20170819 - 05) C-E R. orientipurpurea (SFC 20170819 - 08) F, G Russula sp. (SFC 20160726 - 13). Scale bars: 20 mm.

Figure 4. Basidiospores with scanning electron microscopy images (A, C, E) and drawing images (B, D, F) A, B Russula bella (SFC 20170819 - 05) C, D R. orientipurpurea; (SFC 20170821 - 22 b) E, F Russula sp. (SFC 20160726 - 13). Scale bars: 2 µm.

Figure 7. Microscopic features of Russula sp. (SFC 20160726 - 13) A basidia B basidiola C clavate marginal cells D hymenial cystidia on lamellae sides E subulate marginal cells F hyphal termination at pileus margin G hyphal termination at pileus centre. Scale bars: 10 µm.