Russula bellissima Manz & F. Hampe
Mycobank: MB 840549
Pileus small to medium sized, 10–50 mm diam., young hemispherical or convex, becoming plane and depressed at the centre; margin first even, when old distinctly tuberculate-striate up to 10 mm from the margin, often radially cracking; cuticle hardly peeling, radially disrupted into small patches, pruinose when young, later dry, smooth, matt and pruinose in the centre, colour near the margin when young varnish red (9C8), later red to coral red (9B6-7); near the centre deep red, blood red, dark red (10C7-8), raspberry red (10D7), strawberry red (10D8) or purple brown (10E-F8). Lamellae: 3–5 mm deep, thin, moderately dense, 6–8 at 1 cm near the pileus margin, adnexed, white, slightly anastomosing at the base; lamellulae absent, occasionally forked near the stipe; edges concolorous, entire but pruinose under lens. Stipe: 10–30 × 3–7 mm, usually narrowed towards the base, sometimes cylindrical, surface smooth, white and mainly with a distinct pastel red to red flush, occasionally completely white or sometimes also almost completely red, interior stuffed. Context: white, fragile, unchanging when damaged, reaction with guaiac after 5 s negative on both stipe and lamellae surfaces, reaction to FeSO4 and sulfovanillin negative; taste mild; odour inconspicuous. Spore print: not observed.
Spores (6.9–)7.3–7.8–8.3(–8.9) × (6.1–)6.8–7.2–7.6(–8.4) µm, subglobose to broadly ellipsoid, Q = 1.01–1.1–1.2(–1.29); ornamentation of moderately distant [(4–)5–6(–7) in a 3 µm diam. circle] amyloid spines or warts, (1.1–)1.2–1.4–1.6(–1.7) µm high, fused or connected by fine line connections into often long crests or wings, [(0–)1–3(–4) fusions and the same number of line connections in a 3 µm diam. circle], crests and wings frequently branched and occasionally form closed loops, isolated elements dispersed, edge of crests and wings irregularly wavy; suprahilar spot moderately large, inamyloid. Basidia: (30.5–)34.5–44.1–53.5(–65.0) × (10.5–)11.5–12.6–14.0(–16.0) µm, broadly clavate or obpyriform, 4-spored; basidiola cylindrical, ellipsoid or broadly clavate, ca. 5–10 µm wide. Hymenial cystidia on lamellae sides: absent. Lamellae edges: covered by densely arranged or fasciculate marginal cells. Marginal cells: (27.0–)38.5–46.4–54.5(–61.0) × (5.0–)5.5–6.7–7.5(–9.0) µm; subulate or narrowly lageniform, apically attenuated and constricted to ca. 1–2 µm, sometimes slightly moniliform or flexuous. Pileipellis: (Fig. 6) orthochromatic in Cresyl Blue, gradually passing to the underlying context, 200–300 µm deep; suprapellis 60–130 µm deep, composed of erect or ascending hyphal terminations forming a dry trichoderm, well delimited from 140 to 210 µm deep subpellis composed of horizontally oriented, strongly gelatinized narrow hyphae. Subpellis not well delimited from the underlying context, elongate hyphae gradually changing to sphaerocytes. Acid- resistant incrustations: absent. Hyphal terminations near the pileus margin: composed of long apically attenuated terminal cell and a chain of 1–4 ovoid to barrel shaped, short unbranched cells with one distinctly longer apical cell; constricted on septa, usually not flexuous, oriented towards the pileus surface, usually thin-walled, sometimes slightly thick-walled (up to 1 µm thick); terminal cells mainly subulate or lageniform, apically attenuated and acute, measuring (19–)27.5–38.3–49.0(–66.5) × (3.3–)4.5–5.8–7.0(–9.0) µm, rarely with a forked apex, mixed with dispersed, cylindrical or ellipsoid, distinctly shorter, obtuse terminal cells measuring (7.5–)11.5–17.8–29.5(–42.5) × (3.0–)4.0–4.5–5.0 µm; subterminal cells measuring (4.5–)5.5–8.3–11.5(–16.0) × 4.5–5.3–6.0(–7.0) µm. Hyphal terminations near the pileus centre: similar in shape and also with a mixture of long acute and short obtuse terminal cells, acute ones measuring (12.0–)22.0–35.2–48.5(–79.0) × (2.5–)3.5–4.9–6.5(–8.0) µm, obtuse ones more frequent, measuring (6.5–)8.5–12.0–15.5(–22.0) × (3.5–)4.0–4.9–6.0(–7.5) µm. Primordial hyphae or pileocystidia: absent. Cystidioid hyphae and oleipherous hyphae not observed.
Specimens examine: THAILAND, Chiang Mai Province, Mae On District, about 3 km from Tharnthong lodges, 18° 51′ 55″ N 99° 17′ 23″ E, alt. 725 m, Dipterocarpaceae dominated forest with the presence of some Castanopsis trees, in small groups on loamy soil, 17 July 2012, F. Hampe (GENT FH 12-158, duplicate: MFLU12-0648).
Notes: Russula bellissima is a small species with a bright red pileus and pink colour on the stipe. This colour is distinctive and resembles North American R. mariae, Indian R. intervenosa and Asian R. bella. It is very unlikely that the distribution of any European or North American species is overlapping with the Thai species. However, little is known about the distributional ranges and the ecological niches of other Asian Russula species. Therefore discussing the morphological distinguishing characters between Asian species and R. bellissima is more relevant. Russula bellissima is not closely related to R. bella and it differs from this species by larger spores with a more prominent spore ornamentation, absence of hymenial cystidia on lamellae sides, and subterminally short, ellipsoid cells in the suprapellis arranged in unbranched chains of up to four. The Thai species resembles and is closely related to the Indian R. intervenosa, but it has a more prominent spore ornamentation, hymenial cystidia (on lamellae sides) are absent, and hyphal terminations in the pileipellis are wider.
Fig 1. ML phylogenetic tree inferred from the three-gene dataset (ITS, rpb2, mtSSU) of Russula subsection Amoeninae species, using ML and BI analyses. Three members of R. subg. Heterophyllidiae are used as outgroup. Species in boldface are new species in this study. Bootstrap support values (BS ≥ 50%) and posterior probabilities (PP ≥ 0.90) are shown at the supported branches.