Russula sanguinolenta G.J. Li & Chun Y. Deng, sp. nov.

Index Fungorum number: IF 570742; Fungal Names Number: FN 570742; Facesoffungi number: FoF 14525; Fig. 1

Etymology – Referring to the brightly reddish tinge of pileus.

Holotype – HGAS-MF 013963.

Basidiomes small to medium sized. Pileus 29–57 mm in diam., first hemispheric, then convex, applanate when mature, a tinge of brightly red (9B2335, BC243C), often partly faded
to a paler pinkish red tinge (EC5D73, EC5D73) at center, rarely turning pale orange pink (EEB0AE, FEA188) to white (FFFFFF) smooth, glabrous, slightly viscid when wet; margin slightly striate, rarely cracked, peeling 1/4–1/2 from the edge. Lamellae adnate, 2–4 mm in height, 11–18 pieces per centimeter at edge, rarely forked near the stipes, interveined, white (FFFFFF) first, pale cream (F4EAE0) when mature, unchanging when bruised, lamellulae not observed. Stipes 29–48×10–13 mm, central to subcentral, cylindrical, rugulose longitudinally, pale pink (E08087, FABCB1), rarely faded to white (FFFFFF), a darker pale pinkish red tinge (ED5656, FA7268) near the base, unchanging when injured, smooth, dull, not viscid when wet, slightly tapered downward the base, first stuffed, hollow when mature, annulus absent. Context 3–4 mm thick at pileus center, white (FFFFFF), unchanging, taste acrid, smell indistinct. Spore print cream to pale ocher (Romagnesi IIc–IId).

Basidiospores [150/3/3] (5.6–) 6.1–8 (–8.5) × (4.7–) 5–6.8 (–7.1) μm, Q = (1.00–)1.05–1.37(–1.41), Q = 1.21 ± 0.09, hyaline, subglobose to broad ellipsoid, rarely globose and ellipsoid, ornamentations amyloid, up to 1 μm in height, composed of short crests interconnected as incomplete network, intermixed with a few isolated warts, suprahilar area plage indistinct but amyloid. Basidia 34–43 × 9–13 μm, clavate to subclavate, rarely cylindrical, four-spored, projecting 15–25 μm beyond hymenium, hyaline, sterigmata 5–6 μm long. Hymenial cystidia abundant, 57–99 × 10–16 μm, fusiform, sometimes clavate, ventricose towards the apex, contents crystal, densely distributed, blackish in SV, apex contracted. Pileipellis two layered, distinctly delimited from the spherocytes in context; epipellis an ixotrichoderm, ca. 100–150 μm thick, hyphae hyaline, ascending to erect, rarely septate, 2–4 μm wide; terminal cells cylindrical, tapering towards the apex; pileocystidia abundant, cylindrical to subclavate, 6–9 μm wide, contents granulate, dense, blackish in SV,
apex obtuse, sometimes tapering; subpellis a cutis, hyphae repent, slightly gelatinized, densely interweaved, rarely branched, septate, hyaline, 3–6 μm wide.

Habitat – Scattered in coniferous forest.

Material examined – China, Guizhou Province, Guiyang, Huaxi District, Fengbaoyun Village, in coniferous forest, 1 July 2017, Chun-Ying Deng 2017–131 (HGAS-MF 013963, holotype).

GenBank number – ITS= MT505892.

Notes – A combination of brightly red pileus, pinkish tinged stipe, cream to ocher spore print, and a habitat of coniferous forest indicates this new specie close to Russula sanguinea. This affinity is also supported in phylogenetic analyses (Fig. 2). The R. sanguinolenta group includes R. sanguinea and R. sanguinaria. Russula sanguinea differs from R. sanguinolenta by its subdecurrent lamellae, larger basidiospores (7.2–9.6×6.3–7.4 μm) with lower ornamentations up to 0.8 μm, longer basidia (40–54× 9–12 μm), and wider hymenial cystidia up to 16 μm (Sarnari 1998). Russula sanguinaria is distinguished from R. sanguinolenta by its yellowish turing pileus and larger basidiospores (7.5–9 × 6.5–7.5 μm, Rauschert 1989). The other two closely related species are R. helodes and R. renidens. Russula helodes is distinguished by distinctly greyish context, basidiospores up to 10.5 μm in diam with ornamentations of a complete network, and a habitat of Sphagnum environment. Russula renidens differs in its shiny to glazer pileus, abundant lamellulae in pileus margin, larger basidiospores (7.5–9×6.5–7.5 μm), and narrower hymenial cystidia up to 11 μm wide (Sarnari 1998).

Figure 1 – Microscopic structures of Russula sanguinolenta (HGAS-MF 013963, holotype)). a Basidiomes. b Basidiospores. c Basidia. d Hymenial cystidia. e Suprapellis of pileipellis. Scale bars: a=10 mm, b–e=10 μm

Figure 2 – Maximum likelihood tree illustrating the phylogeny of Russula sanguinolenta (holotype) with related species in R. sect. Persicinae and R. sect. Sardoninae 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. Emeticinae were used as outgroup to root trees. The new isolates are in bold