Russula griseorosea Y.Song, 2024

Song, Yu, Wang, Yu-Yu, Yu, Jin-Ling, Yuan, Rui & Li, Fang, 2024, Phylogenetic and morphological evidence for four new species of Russula (Russulaceae, Basidiomycota) from northwestern China, European Journal of Taxonomy 958, pp. 48-76 : 54-57

Russula griseorosea Y.Song sp. nov.

MycoBank: MB847717

Figs 1– 4 , 11E–F

Diagnosis

Russula griseorosea sp. nov. differs from the phylogenetically closely related R. odorata Romagn. by its grayish pink pileus and irregularly bifurcated lamellae; while the equally close R. sinoparva has very small fruiting bodies (pileus 1.8–3.3 cm in diam.), a pink to deep red pileus and pileocystidia that turn light ash black in SV.

Etymology

The name refers to the mostly grayish pink color of the pileipellis.

Type material

Holotype

CHINA • Shaanxi Province, Hanzhong City, Lianchen Mountain ; 33°12′25″ N, 106°57′39″ E; 593 m a.s.l.; 3 Sep. 2021; Y. Song, K21090308; gregarious on the ground in mixed coniferous and broad-leaf forest, mainly with Quercus variabilis Bl. , Q. aliena Bl. , Q. acutissima Carruth. and Pinus massoniana Lamb. ; GenBank nos: OP828696 (ITS), OP828718 (LSU), OP831169 (rpb2), OP857222 (tef1); SERC [SERC2209] .

Additional material examined

CHINA • Shaanxi Province, Hanzhong City, Lianchen Mountain ; 33°12′25″ N, 106°57′39″ E; 593 m a.s.l.; 13 Sep. 2021; Y. Song, K21091306; gregarious on the ground in mixed coniferous and broad-leaf forest, mainly with Quercus variabilis Bl. , Q. aliena Bl. , Q. acutissima Carruth. and Pinus massoniana Lamb. ; GenBank no: OP828697 (ITS); SERC [SERC2210] .

Description

Basidiomata relatively small sized. Pileus 3–6 cm in diam., hemispherical to convex when young, turning applanate with depressed center at maturity; surface viscid, easy to peel off ⅔ radius when mature, grayish pink (#F8F3DD) when young, then grayish (#FAF9F5) at margin, reddish brown (#E5AB70) at center; margin smooth and entire at first, turning striate or sulcate with age. Lamellae adnate, interveined, white (#FEFEFE), often stained with rust brown (#F0BF8E) when bruised; edge concolorous, smooth. Stipe central, fleshy, fragile, smooth, cylindrical, often tapering upwards, solid at first, turning hollow with age, 2.5–7 × 0.7–1.5 cm, chalky white to white (#FCF3CF, #FBFCFC), often stained with grayish brown (#E5B280) when bruised. Context white (#FCF3CF), unchanging when bruised. Taste mild. Odor indistinct. Spore print not observed.

Basidiospores subglobose to broad ellipsoid, (40/2/2) (6.5–)6.7–7.2–7.5(–8.0) × (5.4–)5.6–5.9– 6.3(–6.6) µm, [Q = (1.10–)1.15–1.21–1.24(–1.29)], hyaline in 5% KOH; ornamentation amyloid, conical to cylindircal warts less than 1.5 µm in height, moderately distant to dense ((4–) 6–7 in a 3 µm diam. circle), often fused into short crests or chains (1–3(–5) in the circle), connected by fine lines, line connections dispersed (1–2 in the circle), forming partial reticulum; suprahilar spot amyloid. Basidia (30–)31.5–35– 39(–42) × (8.5–)10–11.5–12.5 µm, clavate, 2- or 4-spored, thin-walled, with oil droplets; sterigmata 3.4–5.5–8.5 × 1.4–2.0–2.6 µm. Pleurocystidia subcylindrical to subclavate, (37.5–)40.5–52.5–67(–92) × 8–10–13(–14.5) µm, with obtuse, papillate or mucronate apices, thin-walled, with irregular refractive contents, projecting up to 24 µm, unchanging in SV. Cheilocystidia similar to pleurocystidia in shape, but relatively smaller, measuring (29–)35.5–46–53(–60) × 7–10–12 µm. Lamellar trama composed of numerous sphaerocytes surrounded by connective hyphae, sphaerocytes measuring 8–43 × 5–36 µm. Subhymenium pseudoparenchymatous. Pileipellis orthochromatic in cresyl blue, thin, 80–150 µm thick, gelatinized, divided into two layers: suprapellis 30–60 µm thick, composed of ascending to erect hyphae and pileocystidia; subpellis thin, 40–110 µm deep, composed of more horizontal hyphae and pileocystidia; hyphae 2.5–6 µm in diam. Acidoresistant incrustations not observed. Hyphal terminations near the pileus margin thin-walled, occasionally narrow; terminal cells measuring 9–17.5–29(–50) × 2.5–3.5–5 µm, subcylindrical, with obtuse or sharp apices; subterminal cells usually equally wide. Hyphal terminations near the pileus centre of similar structure; terminal cells measuring (11–)12.5–18–25.5(–33) × 2–3–4 µm, cylindrical or slightly narrowed towards apex, apically obtuse-rounded; subterminal cells usually equally wide. Pileocystidia near the pileus margin (29–)31–58–121(–135.5) × 4–6–8 µm, abundant, 1- to 5-celled, thin-walled, cylindrical to subclavate, flexuous, with obtuse apices, with refractive contents, unchanging in SV. Pileocystidia near the pileus center of similar shape, 1- to 5-celled, abundant, measuring (28–)31– 47.5–97(–103) × 3–6–9 µm, with refractive contents, unchanging in SV. Cystidioid hyphae in subpellis and context with granulose or crystalline contents. Oleiferous hyphae in the subpellis. Clamp connections absent in all tissues.

Remarks

Russula griseorosea sp. nov. belongs to the subsect. Puellarinae , a group mainly comprised of small russulas. Russula sinoparva , described from China ( Zhou et al. 2022), is also a member of the subsect. Puellarinae and closely related to R. griseorosea in the phylogeny. Both species are somewhat similar in spore and basidia size and have septate pileocystidia, but R. sinoparva has a very small fruiting body (pileus 1.8–3.3 cm in diam.), a pink to deep red pileus and pileocystidia turning light ash black in SV, which differs from R. griseorosea . Russula yanshanensis C.L.Hou, H.Zhou & G.Q.Cheng , R. subversatilis C.L.Hou, H.Zhou & G.Q.Cheng and R. khinganensis G.J.Li & R.L.Zhao reported from China also belong to subsect. Puellarinae . Russula yanshanensis is diagnosed by a light pink to pink pileus, basidiospores ornamented with short warts (less than 0.6 µm in height); R. subversatilis has a light gray-red to deep red pileus, and pileocystidia becoming light red in SV ( Zhou et al. 2022); R. khinganensis is characterized by a blackish red pileus and slender hymenial cystidia (6–9 µm in diam.) becoming blackish in SV ( Li et al. 2018b), all differ from R. griseorosea . The European R. odorata , another phylogenetically related species, can be distinguished from R. griseorosea by its robust fruiting bodies, a central brown or olive pileus without a pinkish tint and irregularly bifurcated lamellae.

Figures

Fig. 1. Maximum likelihood tree of subg. Russula crown clade based on ITS sequences, bootstrap (BS) values higher than 50% and posterior probability (PP) values higher than 0.9 are displayed around nodes. Newly generated sequences are shown in bold and clades with four new species are highlighted in green.

Fig. 2. Maximum likelihood tree of subgen. Russula crown clade based on 3-locus (nLSU-tef1-rpb2) combined sequences, bootstrap (BS) values higher than 50% and posterior probability (PP) values higher than 0.9 are presented around nodes. Newly generated sequences are shown in bold and four new species are highlighted in green.

Fig. 3. Russula griseorosea Y.Song sp. nov., holotype (SERC2209). A–C. Fruiting bodies. D–E. Basidiospores in Melzer’s reagent showing the amyloid ornamentations. F. Pileocystidia near pileus margin. G–H. Basidia and basidiole in the hymenium. Scale bars: A–C = 1 cm; D–H = 10 µm.

Fig. 4. Line drawings of Russula griseorosea Y.Song sp. nov., holotype (SERC2209). A. Basidia. B. Cheilocystidia. C. Pleurocystidia. D. Pileocystidia near pileus margin. E. Hyphal terminations near pileus margin. Scale bar = 10 µm.

Fig. 11. Photograph of basidiospores under scanning electron microscope.A–B. Russula micangshanensis Y.Song sp. nov., holotype (SERC2201). C–D. R. minirosea Y.Song sp. nov., holotype (SERC2201). E–F. R. griseorosea Y.Song sp. nov., holotype (SERC2209). G–H. R. purpureomarginalis F.Li & Y.Song sp. nov., holotype (SERC2211). Scale bars = 1 µm.