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

Figs 2 D – F , 3 E – I , 6 , 7

Diagnosis.

Russula lavandula is characterised by its purplish-white to violet red pileus with a yellow centre, frequently present lamellulae and furcations, stipe often with pale yellow near the base, isolated basidiospores ornamentation and unbranched cuticular hyphal terminations. It is mainly distinguished from R. lotus Fang Li by its frequently present lamellulae and furcations, subglobose to broadly ellipsoid basidiospores, moderately numerous and narrower hymenial cystidia on lamellae sides and shorter cuticular terminal cells.

Etymology.

‘ lavandula ’ refers to the colour of its pileus similar to lavender.

Holotype.

China, Yunnan Province, Kunming City, Wild Duck Lake , 25 ° 07 ' 34 " N, 102 ° 51 ' 42 " E, alt. 2100 m, 27 Jul 2014, H. J. Li ( RITF 3282 ).

Description.

Basidiomata medium-sized; pileus 40–80 mm in diameter, initially hemispherical when young, convex to applanate with a depressed centre after maturity; margin incurved, striation short or inconspicuous, cracked after maturity; surface dry, glabrous, peeling readily, locally cracking into pale yellow (2 A 3), purplish-white (14 A 2) to greyish-magenta (13 D 5 or 14 E 6) patches, rose (13 B 3), purplish-white (14 A 2) to violet red (14 B 6), sometimes white (1 A 1) at the margin, yellowish-white (1 A 2) to golden yellow (4 C 7) in the centre. Lamellae adnate to slightly adnexed, 10–13 per cm near pileus margin, white (1 A 1), unchanging when bruised, 3–4 mm wide; lamellulae usually present and irregular in length; furcations frequently present throughout the lamellae; edge entire and concolorous. Stipe 40–60 × 16–25 mm, cylindrical, flexuous and tapering towards the base, white (1 A 1), often with pale yellow tinge near the base, solid. Context white (1 A 1), unchanging when bruised, 3–4 mm thick in half of the pileus radius; taste mild; odour inconspicuous. Spore print not observed.

Basidiospores (6.5 –) 7.1–7.7 – 8.3 (– 9.2) × (5.9 –) 6.4–6.9 – 7.5 (– 8.0) µm, Q = (1.01 –) 1.05–1.11 – 1.17 (– 1.24), subglobose to broadly ellipsoid, hyaline in 5 % KOH; ornamentation of small, moderately distant to dense (6–8 in a 3 μm diam. circle) amyloid warts, less than 0.5 μm high, mostly isolated, occasionally connected by short line connections or ridges, not forming a reticulum; suprahilar plage indistinct, inamyloid. Basidia (24.0 –) 28.5–33.5 – 39.0 (– 43.5) × (6.0 –) 7.0–8.5 – 9.5 (– 10.5) µm, clavate, 2 - to 4 - spored, thin-walled; basidiola clavate or subcylindrical, ca. 5–10 µm wide. Hymenial cystidia on lamellae sides moderately numerous, (42.5 –) 47.0–54.5 – 62.5 (– 64.5) × (5.0 –) 6.5–7.5 – 8.5 µm, clavate or fusiform, apically mostly obtuse, partially acute, sometimes with a 4–6 µm and papillate appendage, thin-walled; contents granulose or heteromorphous, reddish-black in sulphovanillin. Hymenial cystidia on lamellae edges shorter, but wider than those on lamellae sides, (35.0 –) 39.0–46.0 – 52.5 (– 56.0) × (6.0 –) 7.0–8.1 – 9.2 (– 10.0) µm, mostly clavate or subcylindrical, apically mostly obtuse, occasionally with 2–5 µm long, papillate or moniliform appendage. Marginal cells undifferentiated. Pileipellis only hyphae of suprapellis metachromatic in cresyl blue, sharply delimited from the underlying context, 300–450 µm deep, two-layered, gelatinised; suprapellis 180–200 µm deep, composed of densely arranged and prostrate to erect hyphal terminations; subpellis 140–260 µm deep, composed of horizontally orientated, intricate and 3–5 μm wide hyphae. Hyphal terminations near the pileus margin unbranched, thin-walled, occasionally flexuous; terminal cells (12.5 –) 14.5–19.5 – 24.5 (– 26.0) × 4.5–5.0 – 5.5 (– 6.5) µm, mainly cylindrical, occasionally lageniform, apically mostly obtuse; subterminal cells usually shorter and slightly wider, ca. 4–7 µm wide, unbranched. Hyphal terminations near the pileus centre shorter and narrower than those near the pileus margin; terminal cells (11.0 –) 13.5–17.0 – 20.5 (– 21.5) × (3.5 –) 4.0–4.2 – 4.5 µm, clavate or cylindrical, apically obtuse; subterminal cells usually wider, ca. 4–6 µm, unbranched. Pileocystidia near the pileus margin always 1 - celled, (20.0 –) 27.0–36.0 – 45.0 (– 48.0) × 4.5–5.5 – 6.0 (– 6.5) µm, clavate, occasionally fusiform, apically usually obtuse, sometimes with 2–6 µm long, round or elliptical appendage, thin-walled; contents crystalline, reddish-black in sulphovanillin. Pileocystidia near the pileus centre similar to those near the pileus margin, (20.0 –) 26.0–36.0 – 45.5 (– 52.5) × 4.0–5.0 – 5.5 (– 6.0) µm.

Habitat.

On the ground under mixed forests of Pinus yunnanensis , Lithocarpus dealbatus and Quercus spp.

Known distribution.

South-western China (Yunnan Province).

Additional specimens examined.

China, Yunnan Province, Chuxiong Yi Autonomous Prefecture, Lufeng City, Guangtong Town, 25 ° 14 ' 43 " N, 101 ° 45 ' 53 " E, 18 Sep 2022, X. L. Gao ( RITF 6329); ibid, 25 ° 14 ' 48 " N, 101 ° 45 ' 28 " E, alt. 2400 m, 24 Sep 2022, X. L. Gao ( RITF 6340); ibid, 25 Sep 2022, X. L. Gao ( RITF 6349); Kunming City, Wuhua District, Qiongzhu Temple, 25 ° 3 ' 58 " N, 102 ° 37 ' 29 " E, alt. 2150 m, 28 Jul 2012, Y. J. Hao ( RITF 3196).

Notes.

Russula lavandula is phylogenetically related to Thai R. banwatchanensis and Indian R. pseudocyanoxantha Paloi, K. Acharya & S. Khatua (Fig. 1 ). However, R. lavandula can be easily distinguished from them by its cracked pileus. Moreover, R. banwatchanensis differs in its darker coloured pileus, lack of lamellulae, thick-walled basidia and often longer pileocystidia of 42.5–127.0 × 2.5–5.0 µm ( Crous et al. 2022) and R. pseudocyanoxantha differs in its darker coloured pileus, lack of lamellae furcations and association with Shorea robusta ( Khatua et al. 2021) . Russula lavandula can be easily confused with four Chinese species, via. R. lotus , R. phloginea J. Song & J. F. Liang , R. purpureorosea and R. subpallidirosea J. B. Zhang and L. H. Qiu in the field. However, R. lotus , originally described from southern China, can be easily distinguished by its absence of lamellae furcations, broadly ellipsoid to ellipsoid basidiospores, dispersed and wider hymenial cystidia on lamellae sides (52.0–70.0 × 10.0–16.0 μm) and longer cuticular terminal cells (10.0–40.0 × 4.0–8.0 μm) ( Li and Deng 2018). Russula phloginea , which occurs in subalpine areas, differs in having lamellae furcations only present near the stipe, smaller basidiospores of (6.0 –) 6.5–8.0 × 5.0–6.5 μm, longer hymenial cystidia of (48.0 –) 60.0–78.5 (– 79.5) × 7.5–9.5 (– 10.0) μm and pileocystidia with a moniliform apex ( Song et al. 2019). Russula purpureorosea and R. subpallidirosea , can be distinguished from R. lavandula by their rosy brown, pale pinkish-purple or pale greyish-pink pileus centre and occurrence at low altitudes ( Zhang et al. 2017; Song 2022). Besides, R. purpureorosea lacks lamellae furcations and has shorter terminal cells of the pileipellis (6.5–15.5 × 2–5.5 μm) and wider pileocystidia (17.0–53.0 × 4.5–9.0 μm) ( Song 2022). In addition, R. cyanoxantha , can be confused with R. lavandula . However, R. cyanoxantha can be distinguished by its uncracked pileus cuticle, longer hymenial cystidia up to 100 µm and slender cuticular hyphal end cells of 2–3 µm ( Bon 1988; Sarnari 1998).

Figures

Figure 1. The RAxML likelihood tree based on the four-gene dataset (ITS + LSU + mtSSU + rpb 2). Support values (BS> 70 %, BPP > 0.95) are displayed above or below the branches, with the maximum values of BS (= 100 %) and BPP (= 1.0) represented by asterisks (*). The four new species are marked with different colours.

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 6. Russula lavandula (RITF 3282, holotype) A basidia B hymenial cystidia on lamellae sides C hymenial cystidia on lamellae edges D basidiola. Scale bar: 10 µm.

Figure 7. Russula lavandula (RITF 3282, holotype) A pileocystidia near the pileus margin B pileocystidia near the pileus centre C hyphal terminations near the pileus margin D hyphal terminations near the pileus centre. Scale bar: 10 µm.