Russula micangshanensis 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 : 60-63

Russula micangshanensis Y.Song sp. nov.

MycoBank: MB847656

Figs 1–2 , 5–6 , 11A–B

Diagnosis

Russula micangshanensis sp. nov. differs from other species of the subsection Olivaceinae by a unique combination of characteristics: spore ornamentation composed of unequal crests and often twinned warts, large basidia (43.5–70.5 × 12.5–17.5 µm], hymenial cystidia (62–157 × 7.5–17 µm) and basidiospores (8.1–10 × 6.5–8.8 µm), and sequence data.

Etymology

The name refers to the locality of the type specimen.

Type material

Holotype

CHINA • Shaanxi Province, Hanzhong City, Xi-xiang County , Micangshan Biosphere Reserve ; 32°37′66″ N, 107°25′49″ E; 1010 m a.s.l.; 2 Aug. 2021; Y. Song, K21080208; 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: OP828702 (ITS), OP828723 (LSU), OP831174 (rpb2); SERC [ SERC2201 ].

Additional material examined

CHINA • Shaanxi Province, Hanzhong City, Xi-xiang County , Micangshan Biosphere Reserve ; 32°37′66″ N, 107°25′49″ E; 1010 m a.s.l.; 2 Oct. 2021; Y. Song, K21100211; 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: OP828703 (ITS); SERC [ SERC2202 ] • Hanzhong City, Mian County; 11 Aug. 2023; Y. Song, Y.Y. Wang, 23081122; gregarious on the ground in mixed coniferous and broad-leaf forest; GenBank no: PP062888 (ITS); SERC [ SERC2303 ] • Hanzhong City, Ning-qiang County; 21 Aug. 2023; Y. Song, R. Yuan, 23082119; 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: PP062889 (ITS); SERC [ SERC2304 ] • same data as for preceding; Y. Song, 23082126; GenBank no: PP062890 (ITS); SERC [ SERC2305 ] • same data as for preceding; Y. Song, 23082128; GenBank no: PP062891 (ITS); SERC [ SERC2306 ] • Hanzhong City, Nan-zheng District; 21 Aug. 2023; Y. Song, 23082139; gregarious on the ground in mixed coniferous and broad-leaf forest; GenBank no: PP062893 (ITS); SERC [ SERC2307 ] • same data as for preceding; Y. Song, 23082142; GenBank no: PP062894 (ITS); SERC [ SERC2308 ].

Description

Basidiomata medium to relatively large sized. Pileus 5.5–8 cm in diam., hemispherical to convex at first, turning applanate with depressed center at maturity; surface glabrous, dry, smooth, sometimes wrinkled concentrically near margin, bright crimson (#FA8072) to light tangerine (#F08080), darker at center, red (#CD5C5C) to light burgundy (#ED6755) when old, sometimes brown (#F9D278) at center; margin entire, often cracked when old. Lamellae adnate, cream (#FFFACD), becoming yellow (#F7D03A) with age, interveined, often forked; edge entire, concolorous, smooth. Stipe central, 4–8 × 1.5–3 cm, cylindrical, sometimes tapering or inflating upwards, solid, fleshy, pinkish (#FFD6BE). Context white, not changing when bruised. Taste mild. Odor indistinct. Spore print cream (#FFFAD1).

Basidiospores subglobose to broadly ellipsoid, (80/4/4) (8.1–)8.3–9.1–9.8(–10) × (6.5–)6.8–7.8– 8.7(–8.8) µm, [Q = (1.06–)1.09–1.15–1.27], hyaline in 5% KOH; ornamentation amyloid, composed of blunt, cylindrical to subcylindrical warts less than 1.5 µm in height, moderately distant to dense ((4–) 6–8 in a 3 µm diam. circle), often fused into short and unequal crests varying in height, warts often twinned, connected by fine lines forming a partial reticulum; suprahilar spot indistinct, amyloid. Basidia (43.5–)46–60–68(–70.5) × (12.5–)14–15.5–17.5 µm, long clavate, 4-spored, thin-walled, often with oil droplets; sterigmata (6.2–)6.4–7.1–8.7 × 1.8–2.2–2.7(–2.9) µm. Pleurocystidia (62–) 65–94–125 (–157) × (7.5–)11–14–17 µm, subcylindrical to fusiform, with papillate, mucronate apices, thin-walled, with irregular refractive contents, projecting up to 53 µm, unchanging in SV. Cheilocystidia 66.5–86.5–96 × 10–13–15 µm, fusiform, with papillate, mucronate apices, thin-walled, with irregular refractive contents, unchanging in SV. Subhymenium pseudoparenchymatous. Marginal cells not observed. Lamellar trama composed of numerous sphaerocytes surrounded by connective hyphae. Pileipellis orthochromatic in cresyl blue, vaguely divided into two layers: 60–120 µm deep suprapellis of ascending to erect hyphae and 30–60 µm deep subpellis composed of more horizontal and dense hyphae; hyphae 3–7 µm in diam., thin-walled, hyaline. Acidoresistant incrustations not observed. Hyphal terminations near the pileus margin flexuous, thin-walled, often narrowed; terminal cells measuring (12.5–)14–23–38.5(–40.5) × 3–4.5–6 µm, subcylindrical, with obtuse or tapering apices, often with slightly wider subterminal cells (up to 8 µm). Hyphal terminations near the pileus centre of similar structure; terminal cells measuring (12–)13–24–41.5(–5) × 3–4.5–6 µm, cylindrical or slightly narrowed towards apex, apically obtuse-rounded or acute; subterminal cells usually equally long but sometimes slightly wider (up to 8 µm). Oleiferous hyphae in the subpellis. Pileocystidia and primordial hyphae absent. Clamp connections absent in all tissues.

Remarks

The pileus surface typically wrinkled concentrically near the margin, the absence of dermatocystidia and primordial hyphae in both pileipellis and stipitipellis, and the orthochromatic pileipellis, all confirm the taxonomic placement of R. micangshanensis sp. nov. within the subsection Olivaceinae . This small group comprises few species, namely R. olivacea Pers. , R. alutacea (Fr.) Fr. and R. vinosobrunnea (Bres.) Romagn. The cap color of R. olivacea is variable, initially olive (the reason for taking the species as a greenish Russula ), later often tinged with red, purple, brown and even gray ( Roberts 2007; Siegel & Schwarz 2016). But all eight specimens of R. micangshanensis mainly appear red and never show any olive tint. While R. olivacea resembles R. micangshanensis in its pinkish-vinaceous flushed stipe, creamyellow gills and relatively large spores (8.5–10.5 × 7.5–9.0 µm), its non-reticulate spores differ from the latter species’ spores, which are ornamented with unequal crests and often twinned warts forming a partial reticulum. Phylogenetically, the ITS sequence similarity between R. micangshanensis and R. olivacea is 96.69%, and they show a clear genetic distance in the multi-locus phylogram. The pileus color of R. alutacea often appears brown and dark red, while R. vinosobrunnea shows dark brown to dark purple, both differing from R. micangshanensis with its bright red cap. Additionally, the former two species have a fruity odor and sweet taste, while R. micangshanensis has an indistinct odor and mild taste. Russula micangshanensis has a wide distribution and a high yield in the Qinling mountains and is popularly consumed as an edible mushroom.

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. 5. Russula micangshanensis Y.Song sp. nov. A–H. Fruiting bodies. A, H. Holotype (SERC2201). B–C. SERC2202. D. SERC2303. E. SERC2304. F. SERC2305. G. SERC2307. I. Basidiospores in Melzer’s reagent showing the amyloid ornamentations (SERC2201). Scale bars: A–H = 1 cm; I = 10 µm.

Fig. 6. Line drawings of Russula micangshanensis Y.Song sp. nov., holotype (SERC2201). A. Basidia. B. Cheilocystidia. C. Pleurocystidia. D. 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.