Russula viridicinnamomea F. Yuan & Y. Song, 2019

Yuan, Fa, Song, Yu, Buyck, Bart, Li, Jingwei & Qiu, Lihong, 2019, Russula viridicinnamomea F. Yuan & Y. Song, sp. nov. and R. pseudocatillus F. Yuan & Y. Song, sp. nov., two new species from southern China, Cryptogamie, Mycologie 20 (4), pp. 45-56 : 47-50

Russula viridicinnamomea F. Yuan & Y. Song , sp. nov.

( Figs 2 , 3 )

SYSTEMATIC POSITION. — Basidiomycota, Agaricomycetes, Russulales , Russulaceae , Russula subg. Heterophyllidia subsect. Heterophyllae .

HOLOTYPE. — China. Guangdong Province, Zhaoqing City, Dinghu Mountain , on the ground in broad-leaf forest, 14.IX.2015, J. B. Zhang K15091418 (holo-, GDGM [ GDGM 75339 ]).

ETYMOLOGY. — Referring to the green tinged buff pileus.

DIAGNOSIS. — R. viridicinnamomea F. Yuan & Y. Song , sp. nov. is mainly characterized by sequence data for the internal transcribed spacers (ITS), its green tinged cinnamon pileus with undulate and easily peeling margin, absence of lamellulae, basidiospores with partially reticulate ornamentations, gloeocystidia changing to grey in SV and thick pileipellis often with inflated subterminal cells.

HABITAT AND DISTRIBUTION. — Gregarious in evergreen broadleaf forest.

ADDITIONAL SPECIMENS EXAMINED. — China. Guangdong Province, Zhaoqing City, Dinghu Mountain, on the ground in broad-leaf forest, 14.IX.2015, J. B. Zhang K15091418-1, (GDGM[GDGM 75340]).

DESCRIPTION

Basidiomata

Small to medium sized, agaricoid.

Pileus

3-5 cm in diam., hemispherical when young, becoming applanate when mature, with entire margin; surface easy to peel to mid-radius, glabrous, dry, not viscid, pale green (#98FB98), with center a very pale greenish-grayish yellow (palegoldenrod, #EEE8AA).

Lamellae

Adnate, equal, rarely forked, off-white (white smoke, #F5F5F5), unchanging when bruised; edge even, concolorous; lamellulae present, but rare.

Stipe

3-4.5 × 0.7-1 cm, central, cylindrical, solid; surface dry, off-white (white smoke, #F5F5F5), longitudinally rugulose.

Context

Off-white (ghost white, #F8F8FF), 1-3 mm thick, unchanging when bruised.

Odour

Indistinct.

Taste

Mild.

Spore print

Whitish.

Basidiospores

Subglobose to ellipsoid, [80/4/2] (5.1-) 5.3-6.1-7.0 (-8.1) ×(3.6-) 4.2-4.7-5.5 (-5.8)µm, Q = (1.05-) 1.12-1.30-1.47 (-1.68), hyaline in 5% KOH; ornamentations amyloid, composed of verrucose to conical warts up to 0.6 µm, linked by fine lines forming incomplete network, intermixed with isolated warts; suprahilar spot not amyloid.

Basidia

31-45.5 × 8.5-11.5 µm, clavate to subcylindrical, 4-spored, rarely 2- or 3-spored, some containing oil droplets when young; sterigmata up to 7 µm long.

Lamellar trama

Composed of nested sphaerocytes surrounded by connective hyphae.

Pleurocystidia

31.5-66 × 4.5-13.5 µm, abundant, fusoid to cylindrical, with rostrate or mucronate apices, thin-walled, with abundant granular contents, becoming dark grey in sulphovanillin (SV).

Cheilocystidia

36.5-63 × 4-12 µm, cylindrical, with capitate apex, thinwalled, some with refractive granular contents, becoming dark grey in SV.

Marginal cells

Not differentiated.

Pileipellis

Orthochromatic in cresyl blue, divided into an upper trichodermal suprapellis and an underlying subpellis of slender, repent to ascending hyphae. Subpellis 350-450 µm deep, composed of septate, thin-walled, hyaline hyphae. Suprapellis 50-80 µm thick, composed of ascending to erect, densely septate hyphal extremities, often with progressively inflating subterminal cells; terminal cells subcylindrical or more frequently distinctly narrowing upward, with obtuse apices; chains of subterminal cells mostly progressively inflated, with more basal cells mostly ellipsoid to subglobose.

Pileocystidia

Abundant, mostly 20.5-84 × 3-6 µm, one-celled, terminal on extremities, narrowly clavate to cylindrical in suprapellis, apex rostrate or obtuse, with granular refractive contents, becoming longer and cylindrical in subpellis, without septa and with distinct refractive contents changing to dark grey in SV.

Stipitipellis

A cutis, orthochromatic in cresyl blue, composed of repent, thin-walled, septate hyphae up to 4.6 µm broad; terminal cells cylindrical.

Caulocystidia

Frequent, cylindrical, mostly 18.5-54 × 3-13 µm, with obtuse apices, without septa, with refractive contents, turning dark grey in SV.

Stipe trama

Composed of connective hyphae and nested sphaerocytes.

Clamp connections

Absent.

Notes

The combination of predominantly equal gills, pale spore print, absence of an amyloid suprahilar spot, no primordial hyphae, but presence of single-celled gloeocystidia and welldifferentiated hyphal extremities are all characters that suggest that R. viridicinnamomea F. Yuan & Y. Song , sp. nov. belongs in subg. Heterophyllidia . Our phylogenetic analysis based on ITS sequences placed it firmly within sect. Heterophyllae, subsect. Heterophyllae, where it is closely related to R. bubalina and R. pseudobubalina ( Li et al. 2018) . The latter subsection was traditionally based on the European R. vesca and R. heterophylla , two species that produce a strong carrot orange reaction to FeSO 4 (which has not yet been verified for our species) and are both unique among European Russulas in possessing thick-walled, needle-shaped cells at the surface of the pileipellis, particularly near the pileus center. Both of these characters have not yet been reported for any of the Chinese species that were recently attributed to this group, except for the confirmed strong reaction to FeSO 4 in R. pseudobubalina and R. subatropurpurea ( Li et al. 2018) . Whereas the three Chinese species that were recently attributed to this subsection are all similar to R. vesca in general color, viz. mostly in shades of pink to pinkish brown with local discolored spots that are yellowish rusty in color, R. viridicinnamomea F. Yuan & Y. Song , sp. nov. is more reminiscent of R. heterophylla because of the green shades on the pileus.

Figures

FIG. 2. — Russula viridicinnamomea F. Yuan & Y. Song, sp. nov.: K15091418 (GDGM 75339, holotype). A, B, Fruiting bodies; C, Pileipellis; D, Terminal elements of pileipellis; E,F, Scanning electronic micrographs of basidiospores. Scale bars: A-B, 1 cm; C, 100 μm; D, 10 μm; E-F, 1 μm.

FIG. 3. — Russula viridicinnamomea F. Yuan & Y. Song, sp. nov. K15091418 (GDGM 75339, holotype). A, Basidia; B, Pleurocystidia; C, Cheilocystidia; D, Pileocystidia; E, Caulocystidia; F, Pileipellis. Scale bars: 10 μm.