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

Figs 2 J – L , 3 M – R , 10 , 11

Diagnosis.

Russula perviridis is characterised by its large basidiomata, smooth pileus surface, frequently present lamellulae and furcations, a coarser stipe with yellow-brown tinge, globose to broadly ellipsoid basidiospores with locally reticulate ornamentation, long hymenial cystidia that turn greyish-black in sulphovanillin and is symbiotic with Quercus semecarpifolia . It differs from R. dinghuensis in longer and wider hymenial cystidia on lamellae edges, subreticulate basidiospores ornamentation and is associated with Quercus semecarpifolia . It differs from R. nigrovirens in frequently present furcations, subreticulate basidiospores ornamentation, longer and wider hymenial cystidia and related host plants.

Holotype.

China, Yunnan Province, Diqing Tibetan Autonomous Prefecture, Shangri La County, Bitahai Nature Reserve , 27 ° 49 ' 42 " N, 99 ° 59 ' 30 " E, alt. 3600 m, 20 Aug 2014, Q. Zhao ( RITF 3131 ).

Etymology.

‘ perviridis ’ refers to a dark green pileus.

Description.

Basidiomata large-sized; pileus 90–150 mm in diameter, initially hemispherical to when young, applanate with a depressed centre when mature; margin usually incurved, striation short or inconspicuous, cracked when mature; surface dry, smooth and glabrous, peeling readily, greyish-green (27 E 5–30 C 5) to dark green (30 F 5), sometimes yellow-brownish (2 C 5) near the centre, greyish-yellow (2 C 3) or greenish-white (26 A 2) at the margin. Lamellae adnate to subfree, 9–12 per cm near pileus margin, white to cream, staining yellowish-brown (5 E 6) when bruised, 6–8 mm wide; lamellulae present and irregular in length; furcations frequently present near the stipe to half of the lamellae; edge entire and concolorous. Stipe 70–90 × 20–40 mm, cylindrical, white (1 A 1) with yellow-brown (2 C 5) tinge, solid. Context white (1 A 1), unchanging when bruised, 4–9 mm thick in half of the pileus radius, relatively soft; taste mild; odour inconspicuous. Spore print not observed.

Basidiospores (5.9 –) 7.1–7.7 – 8.3 (– 9.7) × (5.2 –) 6.1–6.8 – 7.4 (– 8.4) µm, Q = (1.00 –) 1.07–1.14 – 1.21 (– 1.31), globose to broadly ellipsoid, hyaline in 5 % KOH; ornamentation of small, dense (5–10 in a 3 μm diam. circle) amyloid warts, less than 0.5 μm high, reticulate, connected by short line connections or ridges; suprahilar plage large, inamyloid. Basidia (26.0 –) 34.5–42.0 – 59.0 (– 55.0) × (8.0 –) 9.5–11.0 – 12.0 (– 13.0) µm, clavate, 2 - to 4 - spored, thin-walled; basidiola clavate, ca. 6–11 µm wide. Hymenial cystidia on lamellae sides moderately numerous, (56.5 –) 62.5–69.5 – 77.0 (– 81.5) × (6.5 –) 7.0–7.5 – 8.0 µm, fusiform or clavate, apically mostly obtuse, sometimes acute, thin-walled; contents heteromorphous, greyish-black in sulphovanillin. Hymenial cystidia on lamellae edges similar to those on lamellae sides, (45.0) 54.0–64.5 – 74.5 (– 79.5) × 6.0–7.5 – 8.5 (– 10.0) µm, mostly clavate, occasionally fusiform, apically mostly obtuse, sometimes with 3–5 µm long appendage, thin-walled; contents granulose or heteromorphous, greyish-black in sulphovanillin. Marginal cells (23.0 –) 24.5–27.5 – 33.5 × (4.5 –) 5.5–6.0 – 7.0 µm, clavate or subcylindrical, occasionally flexuous. Pileipellis only hyphae of suprapellis weakly metachromatic in cresyl blue, sharply delimited from the underlying context, 300–360 µm deep, two-layered, not gelatinised; suprapellis 180–200 µm deep, composed of erect and densely arranged hyphal terminations; subpellis 140–180 µm deep, composed of horizontally orientated, intricate and 3–5 μm wide hyphae. Hyphal terminations near the pileus margin occasionally branched, thin-walled, sometimes flexuous; terminal cells (17.0 –) 20.0–25.5 – 31.5 (– 38.0) × 3.0–4.0 – 4.5 (– 6.0) µm, usually clavate or subcylindrical, apically tapering; subterminal cells usually shorter, ca. 4–6 µm wide, occasionally branched. Hyphal terminations near the pileus centre shorter than those near the pileus margin; terminal cells (13.0 –) 14.5–20.5 – 26.5 (– 32.0) × 3.5–4.0 – 4.5 µm. Pileocystidia near the pileus margin always 1 - celled, (36.5 –) 40.5–47.5 – 55.0 (– 60.0) × (3.0 –) 3.5–4.0 – 4.5 µm, fusiform or subcylindrical, apically usually obtuse, sometimes with 2–6 µm long, round or elliptical appendage, thin-walled; contents heteromorphous or granulose, greyish-black in sulphovanillin. Pileocystidia near the pileus centre similar to those near the pileus margin, (26.5 –) 28.0–36.0 – 44.0 (– 50.5) × 3.0–3.5 – 4.5 µm.

Habitat.

On the ground under broad-leaved forests dominated by Quercus semecarpifolia .

Known distribution.

South-western (Sichuan and Yunnan Provinces) and western China (Xizang Autonomous Region).

Additional specimens examined.

China, Sichuan Province, Ganzi Tibetan Autonomous Prefecture, Daocheng County, Yading Village, 4 Aug 2022, X. L. He ( RITF 6734); Yunnan Province, Diqing Tibetan Autonomous Prefecture, Deqin County, Wudi Lake, 27 ° 48 ' 47 " N, 99 ° 42 ' 50 " E, alt. 3300 m, 11 Sep 2023, Y. L. Chen & J. Y. Liang ( RITF 6982, 6983); Shangri La City, Bita Sea Scenic Area, 27 ° 49 ' 39 " N, 99 ° 59 ' 28 " E, alt. 3600 m, 15 Jul 2014, Q. Zhao ( RITF 3143); Xizang Autonomous Region, Linzhi City, Motuo County, 29 ° 22 ' 13 " N, 95 ° 26 ' 59 " E, alt. 1800 m, 15 Jul 2014, Q. Zhao ( RITF 2912); Lhasa City, Mozhugongka County, Zhaxigang Township, 29 ° 42 ' 10 " N, 92 ° 4 ' 44 " E, alt. 4500 m, 7 Aug 2023, Y. Zhang ( RITF 6790).

Notes.

Phylogenetic analyses showed that R. perviridis is related to two European species, R. langei Bon and R. cyanoxantha and the Chinese species R. nigrovirens . However, R. langei has a violaceous pileus, a white stipe with a lilac tinge and narrower cuticular hyphal terminations (2.0–3.0 μm) ( Bon 1988), whereas R. cyanoxantha has non-reticulate basidiospore ornamentation and longer hymenial cystidia up to 100 μm ( Bon 1988; Sarnari 1998). Russula nigrovirens differs in having patches on the pileus surface, furcations rarely present near the stipe, basidiospore ornamentation that does not form a reticulum and smaller hymenial cystidia (46.0–55.0 × 6.5–8.5 μm) on the lamellae edges ( Zhao et al. 2015). Morphologically, R. perviridis has a green pileus as in Chinese R. dinghuensis J. B. Zhang & L. H. Qiu. However , R. dinghuensis differs in its shorter and narrower hymenial cystidia on lamellae edges (45.0–52.0 × 4.0–6.0 μm) and isolated basidiospore warts ( Zhang et al. 2017). Furthermore, R. perviridis can be clearly distinguished from similar Cyanoxanthinae species in its habitat. Russula perviridis is distributed in subalpine areas (over 2,000 m) and is associated with Quercus semecarpifolia . However, R. nigrovirens is associated with Picea spp. , Rhododendron spp. , Sorbus spp. and Abies spp. and R. dinghuensis is distributed in low-altitude areas (below 1,000 m).

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 10. Russula perviridis (RITF 3131, holotype) A basidia B basidiola C marginal cells D hymenial cystidia on lamellae sides E hymenial cystidia on lamellae edges. Scale bar: 10 µm.

Figure 11. Russula perviridis (RITF 3131, 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.