Russula chlorina G.J. Li & Chun Y. Deng, sp. nov.
Index Fungorum number: IF 570737; Mycobank number: MB 570737; Fungal Names Number: FN 570737; Facesoffungi number: FoF 14523; Figs. 1a, b, 2, 3a
Etymology – Referring to the pale yellowish green pileus.
Holotype – HBAU 15024.
Basidiomes small to medium sized. Pileus 29–37 mm in diam, first hemispheric, then convex, plane when mature, not depressed at center, a tinge of pale green centrally intermixed with yellow, light green (DDE5D9, E3E8DC), to pale yellowish green (B5CF61, BFD833), sometimes faded to a paler yellowish tinge (F1F2F1, EFEFDF), sometimes intermixed with yellowish ocher tinge (91672C, D8AC59), smooth, dull, slightly viscid when wet; margin not striate, not cracked, peeling 1/4–1/3 from the edge, sometimes entirely faded to pale yellow (F1E5BE, EFEFDF). Lamellae adnate, 2–3 mm in height, 17–20 pieces per centimeter at edge, often forked near the stipes, interveined, white (FFFFFF), unchanging when injured, lamellulae absent. Stipes 26–38×8–12 mm, central, cylindrical, rugulose longitudinally, white (FFFFFF), turning pale ocher (F1E5BE, F4EAE0) when bruised, smooth, dull, not viscid when wet, slightly tapered downward the base, first stuffed, hollow when old, annulus absent. Context 2 mm thick at pileus center, white (FFFFFF), unchanging, taste mild, smell indistinct. Spore print white to pale cream (Romagnesi Ib–IIa).
Basidiospores [150/3/3] (5.3–)5.6–6.9(–7.3) × (4.6–)4.9–5.9 μm, Q=1.07–1.28 (1.31), Q=1.19±0.09), hyaline, subglobose to broad ellipsoid, rarely globose and ellipsoid, ornamentations amyloid, up to 0.7 μm in height, composed of warts and short ridges interconnected as incomplete network, certain amount of isolated warts and short crests also exist, suprahilar area plage indistinct and inamyloid. Basidia 33–44 × 6–10 μm, subcylindrical, subclavate to clavate, rarely cylindrical, four-spored, projecting 5–20 μm beyond hymenium, hyaline, sterigmata 5–7 μm long. Hymenial cystidia infrequent, 58–77×8–14 μm, fusiform to clavate, sometimes ventricose towards the apex, contents crystal, unevenly distributed, blackish grey in sulfovanillin (SV), apex obtuse, rarely subacute. Pileipellis two layered, vaguely delimited from the spherocytes in context; epipellis a trichoderm, ca. 50–100 μm deep, hyphae erect, oblique to repent, hyaline, mostly 2–4 μm wide, rarely 5–7 μm; terminal cells fusiform, subulate to bayonet-shaped, attenuate towards the apex; pileocystidia abundant, 5–8 μm wide, rarely septate, cylindrical, narrowing towards the apex, contents crystal, unevenly distributed, blackish in SV; subpellis composed of somewhat gelatinized, densely interweaved, branched and septate, hyaline hyphae 2–5 μm wide, rarely intermixed with spherocytes 15–25 μm.
Habitat – Single or scattered in coniferous and broadleaved intermixed forest.
Material examined – China, Guizhou Province, Yinjiang County, Chanxi Township, Fengxiangping Nature Reserve, in broad-leaved forest, 31 July 2019, Lu-Yao Shi, Guo-Jie Li 20190156 (HBAU 15024, holotype).
GenBank number – ITS=MT505888.
Notes – The new species Russula chlorina clusters with R. grisea, R. ionochlora, R. subalpinogrisea and an undescribed Russula speciemen from Papua New Guinea (TU 110491) in phylogenetic analysis (Fig. 4). The morphological differences between R. chlorina and the other three known species are as follows: R. grisea differs by its violet, bluish, rarely greenish pileus, lilac shade on stipes, cream spore print (IIc), larger basidiospores (6.4–8.5×5.4–6.5 μm), and longer hymenial cystidia (6.4–8.5×5.4–6.5 μm) with lower warts up to 0.5 μm; R. ionochlora can be distinguished by its larger basidiospores (6.4–8×4.7–6 μm), inflated subapical cells, and baynet shaped terminal cells in pileipellis (Sarnari 1998); R. subalpinogrisea is separated by its strongly viscous pileus, arger basidiospores (6.16–9.45×5.85–8.38 μm), longer basidia 47–59×10.5–13.5 μm, narrower pileocystidia 4.8–5.2 μm wide, and a habitat of subalpine mixed forest (Das et al. 2018).
Figure 1 – Basidiomes of new Russula species (holotypes). a, b Russula chlorina. c, d R. luteocarpa. Scale bars: a–d=10 mm
Figure 2 – Microscopic structures of Russula chlorina (HBAU 15024, holotype). a Basidia. b Hymenial cystidia. c Suprapellis of pileipellis. Scale bars: a–c=10 μm
Figure 3 – Basidiospores of new Russula species (holotypes). a Russula chlorina. b R. chrysea. c R. cruenta. d R. luteocarpa. Scale bars: a–d=10 μm
Figure 3 – Maximum likelihood tree illustrating the phylogeny of Russula chlorina and R. luteocarpa (holotype) with related species in R. sect. Heterophyllae based on ITS sequences. Branches are labeled with maximum likelihood bootstrap higher than 50%, and Bayesian posterior probabilities more than 0.9 respectively. Sequences of R. sect. Substriatinae were used as outgroup to root trees. The new isolates are in bold