Russula lilaceofusca Y. L. Chen & J. F. Liang, 2024

Chen, Yanliu, Chen, Bin, Liang, Ruoxi, Wang, Shengkun, An, Mengya, Zhang, Jinhua, Liang, Jingying, Wang, Yaxin, Gao, Xuelian & Liang, Junfeng, 2024, Four new species of Russula subsect. Cyanoxanthinae from China (Russulales, Russulaceae), MycoKeys 107, pp. 21-50 : 21-50

Russula lilaceofusca Y. L. Chen & J. F. Liang , sp. nov.

Figs 2 G – I , 3 J – L , 8 , 9

Diagnosis.

Russula lilaceofusca is mainly characterised by its lilac brown to dark brown pileus, crowded lamellae with the presence of lamellulae and furcations, stipe often turning reddish-yellow when bruised, subreticulate basidiospores ornamentation and clavate hymenial cystidia often with capitate appendage whose contents change to reddish black in sulphovanillin. It can differ from R. cyanoxantha in shorter hymenial cystidia and wider cuticular terminal cells and differ from R. fusiformata in frequently present lamellulae and furcations, clavate hymenial cystidia on lamellae edges that have no reaction in sulphovanillin and occasionally branched cuticular hyphal terminations.

Holotype.

China, Yunnan Province, Chuxiong Yi Autonomous Prefecture, Lufeng City , G 30 ).

Etymology.

‘ lilaceofusca ’ refers to a lilac brown pileus.

Description.

Basidiomata medium-sized; pileus 40–60 mm in diameter, initially hemispherical when young, convex to applanate after mature; margin incurved, no striation, not cracked; surface dry, glabrous, reddish-white (8 A 2), lilac (15 B 4), brown (7 E 5) to dark brown (7 F 5). Lamellae adnate, very crowded, 20–24 per cm near pileus margin, cream, unchanging when bruised; lamellulae present and irregular in length; furcations frequently present; edge entire and concolorous. Stipe 35–50 × 8–17 mm, cylindrical to subcylindrical, slightly expanded towards the base, white (1 A 1), staining reddish-yellow (4 A 6) when touched, solid. Context white (1 A 1), unchanging when bruised, soft; taste mild; odour inconspicuous. Spore print not observed.

Basidiospores (6.5 –) 7.0–7.8 – 8.7 (– 10.5) × (5.5 –) 6.1–6.9 – 7.7 (– 9.4) µm, Q = (1.05 –) 1.09–1.13 – 1.17 (– 1.26), subglobose to broadly ellipsoid; ornamentation of small to medium, dense (5–9 in a 3 μm diam. circle) amyloid warts, less than 0.5 μm high, subreticulate, connected by short line connections or ridges; suprahilar plage large, inamyloid. Basidia (26.5 –) 30.5–38.5 – 47.0 (– 56.0) × (9.5 –) 10.5–12.5 – 14.0 (– 15.5) µm, clavate or ellipsoid, 1 - to 4 - spored, thin-walled; basidiola clavate or ellipsoid, ca. 8.0–13.0 µm wide. Hymenial cystidia on lamellae sides dispersed to moderately numerous, (39.5 –) 43.5–48.5 – 53.5 (– 60.0) × (8.0 –) 9.5–10.5 – 11.5 (– 12.0) µm, mostly clavate, apically mostly obtuse, often with a 2.0–4.5 µm round appendage, thin-walled; contents granulose or heteromorphous, reddish-black in sulphovanillin. Hymenial cystidia on lamellae edges shorter and narrower than those on lamellae sides, (31.0 –) 36.0–41.5 – 47.0 (– 54.0) × (7.0 –) 7.5–8.5 – 10.0 (– 10.5) µm, mostly clavate, apically mostly obtuse, occasionally with a 2–3 µm long round or elliptical appendage, thin-walled; contents heteromorphous, reddish-black in sulphovanillin. Marginal cells (13.5 –) 15.0–18.5 – 22.0 (– 26.0) × 4.0–5.0 – 5.5 (– 6.5) µm, lageniform, clavate or subcylindrical. Pileipellis only hyphae of suprapellis metachromatic in cresyl blue, sharply delimited from the underlying context, two-layered, gelatinised; suprapellis 130–200 µm deep, composed of loosely arranged and erect hyphal terminations; subpellis 90–200 µm deep, composed of horizontally orientated and intricate hyphae. Hyphal terminations near the pileus margin occasionally branched, thin-walled, often flexuous; terminal cells (11.0 –) 12.5–18.5 – 24.0 (– 32.0) × (3.0 –) 3.5–4.0 – 5.0 (– 5.5) µm, mainly lageniform or cylindrical, apically obtuse, sometimes attenuated or constricted; subterminal cells usually longer and slightly wider, ca. 3.5–7.0 µm wide, occasionally branched. Hyphal terminations near the pileus centre slightly shorter than those near the pileus margin; terminal cells (9.5 –) 11.5–16.0 – 20.0 (– 25.5) × (3.0 –) 3.5–4.0 – 5.0 (– 5.5) µm, lageniform or cylindrical, apically obtuse, sometimes attenuated or constricted; subterminal cells usually equal or slightly wider, ca. 2.8–6.6 µm, occasionally branched. Pileocystidia near the pileus margin always 1 - celled, (23.5 –) 26.5–35.0 – 43.5 (– 51.0) × (3.5 –) 4.0–4.5 – 5.5 µm, subfusiform or cylindrical, apically usually obtuse, always with 2–3 µm long, round or elliptical appendage, thin-walled; contents heteromorphous, reddish-black in sulphovanillin. Pileocystidia near the pileus centre similar to those near the pileus margin, (30.5 –) 34.5–39.5 – 44.5 (– 53.0) × 3.5–4.0 – 4.5 (– 5.5) µm.

Habitat.

On the ground of broad-leaved forests dominated by Quercus spp. or mixed forests with Pinus spp.

Known distribution.

Central (Hubei Province) and south-western China (Guizhou and Yunnan Provinces).

Additional specimens examined.

China, Guizhou Province, Zunyi City, Kuankuoshui National Nature Reserve, 28 ° 14 ' 29 " N, 107 ° 11 ' 59 " E, alt. 1750 m, 27 Sep 2014, H. J. Li ( RITF 3761); Hubei Province, Shennongjia Forest District, Jianglongping, 31 ° 25 ' 46 " N, 110 ° 20 ' 18 " E, alt. 1500 m, 9 Aug 2015, Y. K. Li ( RITF 2645); ibid, 11 Aug 2015, Y. K. Li ( RITF 2631).

Note.

Phylogenetic analyses showed that R. lilaceofusca was closely related to the Indian species R. lakhanpalii and R. variata from the United States. However, R. lakhanpalii differs in having a yellowish-white to pale yellow areolate pileus with orange-brown centre, cystidia that show no change in sulphovanillin and longer and wider pileocystidia of (27.0 –) 40.0–63.0 – 86.5 (– 123.0) × (4.0 –) 4.5–5.5 – 6.5 (– 7.0) μm near the pileus margin ( Ghosh et al. 2020). Russula variata differs in having a green pileus and basidiospores with higher warts of 0.4–1.0 µm ( Hessler 1960; Burge 1979). In morphology, Chinese R. fusiformata Y. Song can be easily confused with this species. However, R. fusiformata can be distinguished by its striate pileus margin, absence of lamellulae and furcations, fusiform hymenial cystidia on the lamellae edges, cystidia that show a negative reaction in sulphovanillin and unbranched terminal cells in the pileipellis ( Song 2022). Russula lilaceofusca is similar to R. cyanoxantha , but R. cyanoxantha has a greenish-violet pileus, longer hymenial cystidia up to 100 μm and slender cuticular hyphal end cells of 2–3 µm ( Romagnesi 1967; Bon 1988; Sarnari 1998).

Figures

Figure 2. SEM photos of basidiospores of the four new species A – C Russula atrochermesina (RITF 6878, holotype) D – F Russula lavandula (RITF 6329) G – I Russula lilaceofusca (RITF 6330, holotype) J – L Russula perviridis (RITF 3131, holotype). Scale bars: 20 µm (G); 10 µm (A, B, D, E, H, J, K); 5 µm (C, F, I, L).

Figure 3. Fruiting bodies photos of four new species A – D Russula atrochermesina (A-C-RITF 6878, holotype, D-RITF 6460) E – I Russula lavandula (E-F-RITF 6329, G-H-RITF 6340, I-RITF 3282, holotype) J – L Russula lilaceofusca (J-K-RITF 6330, holotype, L-RITF 2631) M – R Russula perviridis (M-N-RITF 3131, holotype, O-P-RITF 6982, Q-R-RITF 6983). Scale bars: 40 mm (A, B, D – G, I, J, M – O); 5 mm (C, L); 20 mm (H, K, P, Q, R).

Figure 8. Russula lilaceofusca (RITF 6330, holotype) A hymenial cystidia on lamellae sides B basidiola C marginal cells D basidia E hymenial cystidia on lamellae edges. Scale bar: 10 µm.

Figure 9. Russula lilaceofusca (RITF 6330, holotype) A hyphal terminations near the pileus margin B hyphal terminations near the pileus centre C pileocystidia near the pileus margin D pileocystidia near the pileus centre. Scale bar: 10 µm.