Russula purpureorosea Y.Song, 2022

Song, Yu, 2022, Species of Russula subgenus Heterophyllidiae (Russulaceae, Basidiomycota) from Dinghushan Biosphere Reserve, European Journal of Taxonomy 826, pp. 1-32 : 14-17

Russula purpureorosea Y.Song sp. nov.

MycoBank: MB828229

Index Fungorum: IF559327

Figs 4–5 , 6a

Diagnosis

Russula purpureorosea sp. nov. can be separated from other known species by its ITS sequence with a similarity less than 95.5% when aligned. The species is morphologically characterized by the pale pinkish purple pileus with even or incurved margin, adnate and crowded lamellae with lamellula, thick metachromatic pileipellis, terminal elements of pileipellis with some inflated terminal and subterminal cells.

Etymology

The name refers to pale pinkish purple pileus.

Material examined

Holotype CHINA • Guangdong Province, Zhaoqing City, Dinghushan Biosphere Reserve, on the ground in mixed coniferous and broad-leaf forest; 5 May 2017; Y. Song, H17050506 ; GenBank no.: MK049976 ( ITS); GDGM75331 .

Additional material

CHINA • Guangdong Province, Zhaoqing City, Dinghushan Biosphere Reserve, on the ground in broad-leaf forest mainly with Fagaceae trees; 18 May 2018; Y. Song; GenBank no.: MK049977 ( ITS); GDGM75334 .

Description

Basidiomata small to medium-sized. Pileus 3.5–6 cm in diam., applanate or with a slightly depressed center; surface glabrous, dry, pale pinkish purple (#D8BFD8), often with rosy brown (#BC8F8F) center; margin even or slightly incurved, smooth to slightly striate when young, sulcate or cracked with age. Lamellae adnate, ivory (#FFFFF0), yellowish when dried, unchanging after bruising, not forking, interveined, with even, concolorous edges; lamellulae frequent when young, but not regularly polydymous. Stipe 25–40 × 8–12 mm, cylindrical, central, solid; surface white (#FFFFFF), glabrous, dry, slightly longitudinally rugulose. Context 3–5 mm thick, whitish (#FFFFFF), unchanging after bruising or with FeSO 4. Taste mild. Odor indistinct. Spore print whitish.

Basidiospores subglobose to broadly ellipsoid, (40/2/2) (6.1–)6.4–7.0–7.7(–7.8) × (5.3–)5.4–5.8– 6.3(–6.6) μm, Q = (1.06–)1.18–1.20–1.28(–1.36); ornamentation amyloid, composed of conical to subcylindrical warts, not exceeding 0.6 μm in height, mostly isolated; hyaline in 5% KOH. Basidia 27–41–46 × 8.5–12–14.5 μm, mostly 4-spored, rarely 2-spored, clavate to subcylindrical; sterigmata up to 6 μm in height. Lamellar trama mainly composed of nested spherocytes (18–69 × 7–42 μm) surrounded by connective hyphae. Pleurocystidia 32–55–85 × 3.5–7–9 μm, subcylindrical to subfusiform, apex obtuse or mucronate, often with refractive heteromorphous contents that are mostly restricted to upper part of cystidia, negative in SV. Cheilocystidia 54–60–95 × 7–8.5–10 μm, slender, clavate to subfusiform, apex obtuse, with abundant refractive heteromorphous contents. Marginal cells not differentiated. Pileipellis metachromatic in cresyl blue, 57–112 μm thick, composed of suprapellis and subpellis; suprapellis trichoderm to palisade, composed of ascending to erect hyphae, some with chains of inflated subterminal cells; subpellis composed of horizontally oriented hyphae, 2–9 μm in diam.; terminal cells at center 6.5–15.5 × 2–5.5 μm, cylindrical to clavate, some inflated, apices obtuse, rarely attenuate; terminal cells at margin similar in shape, but more or less slender, rarely inflated. Pileocystidia 17–53 × 4.5–9 μm, clavate to fusiform, one-celled, thin-walled, some subterminally constricted, with mucronate or capitate apices, with distinct contents, unchanging in SV, also present in subpellis. Stipitipellis a cutis, composed of thin-walled, interwoven, septate, cylindrical hyphae 1.5–3.7 μm in diam. Caulocystidia 9–38 × 2.3–7 μm, rare, subcylindrical to narrow clavate. Clamp connections absent.

Remarks

Russula purpureorosea sp. nov. has equal gills, lamellulae not frequent, context unchanging, spore print whitish, spores with inamyloid suprahilar spot, primordial hyphae absent, gloeocystidia abundant, terminal elements inflated; all these characters indicate that R. purpureorosea belongs to subgen. Heterophyllidiae subsect. Cyanoxanthinae in morphology. Our phylogenetic analysis based on ITS shows that R. purpureorosea is closely related to R. pallidirosea Kropp within subsect. Cyanoxanthinae . Russula purpureorosea can be distinguished from related species by its pinkish purple to rosy brown pileus with lamellulae. Compared with R. purpureorosea , R. pallidirosea has smaller pinkish pileus (cap 1.5–2.5 cm in diam.) with margins inrolled at first, becoming uplifted with age, lamellae occasionally forked, lamellula present and stipe tapering toward the base. Basidiospores of R. pallidirosea have low unconnected amyloid ornamentations which are generally shorter than in R. purpureorosea .

Figures

Fig. 4. Russula purpureorosea Y.Song sp. nov., holotype (GDGM75331). a–c. Fruiting bodies. d. Basidia. e–f. Basidiospores under scanning electron microscope. Scale bars: a–c = 1 cm; d = 10 μm; e–f = 1 μm.

Fig. 5. Russula purpureorosea Y.Song sp. nov., holotype (GDGM75331). a. Basidia. b. Pleurocystidia. c. Cheilocystidia. d. Pileocystidia. e. Caulocystidia. f. Pileipellis. Scale bars = 10 μm.

Fig. 6. Line drawings of basidiospores.a. Russula purpureoroseaY.Song sp. nov., holotype (GDGM75331). b. Russula fusiformata Y.Song sp. nov., holotype (GDGM 75333). Scale bar = 1 μm.