Russula californiensis Burl., Mycologia

Adamčík, Slavomír, Jančovičová, Soňa & Buyck, Bart, 2015, Type-studies in American Russula subsection Decolorantes (Russulales, Basidiomycota), part II., Phytotaxa 231 (3), pp. 245-259 : 246-249

Russula californiensis Burl., Mycologia 28(3): 262. 1936. Figs. 1–9

Original description:—Pileo firmo, convexo-explanato, depresso, glabro, jove pluvio viscido, pellicula subseparabeli, sene-sanguinea pallidioreve, 8.5–25 cm. lato; margine reflexo patenteve, levi, infrequenter leviter striato-tuberculoso; carne alba, fracta tarde subcinerascente, acri; lamellis pallidis, aequalibus, postice furcatis et attenuatis sed proxime stipitem rotundatis et adnectis dente, venoso-connexis, confertis; stipite albo tarde cinerascente cum siccescit, inaequali, farcto, 1.3–4 cm. × 8–18 cm.; sporis melleis, 7.5–8.75 μ × 9–10 μ, reticulatis.

Spores subglobose, (8.6–)9–10(–10.6) × (7.6–)7.9–8.6(–9) μm, average 9.4 × 8.2 μm, Q=(1.1–)1.12–1.17(–1.2), average Q=1.15, with a subreticulate ornamentation of low, obtuse, moderately dense, amyloid warts [5–7(–9) in a 3 μm diam. circle], 0.3–0.5 μm high, connected by numerous fine line connections [2–5(–8) in the circle], often fused in long chains [(0–)1–4(–5) fusions in the circle], without isolated warts; suprahilar plage relatively large, amyloid. Basidia (50–)52.5–61.5(–64) × (12–)12.5–14(–14.5) μm, average 57 × 13 μm, 4-spored, clavate-pedicellate; basidioles first cylindrical than clavate, 5–10(–12) μm wide. Subhymenium pseudoparenchymatic. Lamella trama mainly composed of large sphaerocytes. Hymenial cystidia widely dispersed, 150–300/mm 2, distinctly protruding towards gill edge, clavate to fusiform, pedicellate, thin-walled or with slightly thickened walls, measuring (70–)73–93.5(–133) × 9–13(–15.5) μm, average 83 × 11.5 μm, mostly mucronate or narrowing at the apex, with 2–5(–7) μm long apical appendage, almost completely filled with heteromorphous, mostly granular-banded contents, staining dark grey-brown in sulfovanillin. Marginal cells smaller than basidioles, measuring (15–)17.5–28.5(–33) × (3.5–)4–5 μm, average 22 × 4.5 μm, subcylindrical or fusiform, often flexuous, sometimes slightly moniliform or subapically constricted. Pileipellis orthochromatic in Cresyl Blue, two-layered and sharply delimited from the underlying sphaerocytes of the context; distinctly divided in a loose, 90–100 μm deep and strongly gelatinized suprapellis of erect or ascending hyphal ends and pileocystidia covered with a 20–30 μm thick, gelatinous layer containing some very dispersed hyphal endings, and underneath this suprapellis a less gelatinized, 60–80 μm deep, subpellis of intricate, more horizontally oriented hyphae. Acidoresistant incrustations absent. Hyphal extremities near the cap margin composed of a single or a few cells only; the terminal cell subcylindrical and variable in length, measuring (21–)30–52(–72) × 3.5–5(–7) μm, average 40.5 × 4 μm, often moniliform and flexuous toward the tip, or apically slightly constricted, in the cap center more densely packed, often shorter, measuring 14–30.5(–45) × 3–5(–7) μm, average 23.5 × 4 μm, usually less flexuous, sometimes with distinctly thickened walls; subterminal cells branched or not and equally wide, usually already descending in subpellis. Pileocystidia large, mostly one to three-celled, with terminal cell measuring (27–)47–96(–113) × (6–)8.5– 12.5(–13.5) μm, average 71 × 10.5 μm, mostly clavate-pedicellate, obtuse-rounded or mucronate, in Congo Red with granular to crystalline contents, distinctly graying in sulfovanillin, thin-walled or with slightly thickened wall, without incrustations. Cystidioid hyphae in subpellis of cap and trama present but dispersed. Clamp connections absent in all parts.

Examined material:— UNITED STATES. California. Monterey Co., Pacific Grove , 4 Jan. 1928, G.S. Burlingham (NY00618793; NY00618794, lectotype, here designated) .

Commentary: — This species undoubtedly belongs in Decolorantinae because of its graying flesh, spores with amyloid suprahilar spot, distinct pileocystidia and lack of acidoresistant incrustations. The large, subglobose spores with subreticulate ornamentation are very distinctive and there is no similar species known from Europe. In North America, R. magna Beardslee described from the Eastern US (North Carolina), is very similar and resembles R. californiensis not only in having similar spores and producing large basidiomata with firm flesh and a pale yellow spore print, but also in having voluminous pleurocystidia and basidia, flexuous hyphal terminations in the suprapellis near the cap margin and cystidioid hyphae in the underlying trama ( Adamčík & Buyck 2011). Both species are certainly closely related and the few differences between both type collections are difficult to appreciate without studying more collections or support from molecular data: R. californiensis has a red cap, almost no odor, longer and narrower hyphal terminations in the pileipellis near the cap margin and clavate-pedunculate pileocystidia that are 8.5–12.5 μm wide, whereas R. magna has a buff colored cap, a distinct odour, and the pileocystidia are mostly subcylindrical and up to 7 μm wide ( Adamčík & Buyck 2011).

Both specimens present in the New York Botanical Garden (NY) and marked as ‘type’ correspond very likely to the single collection referred to in the protologue. Nevertheless, one of these specimens is here designated as the lectotype because the material is in better condition and more abundant. It was studied earlier by L.R. Hesler and H.D. Thiers. The second box remains the syntype.

Figures

FIGURES 1–3. Russula californiensis (lectotype). 1. Pileocystidia. 2. Hyphal extremities in the cap center. 3. Hyphal extremities near the cap margin. Contents of cystidia are represented as observed in Congo Red for some elements only, the others are simply filled with dots to indicate their cystidial nature. Scale bar equals 10 μm. Drawings by S. Jančovičová.

FIGURES 4–9. Russula californiensis (lectotype). 4. Basidia. 5. Basidioles. 6. Marginal cells. 7. Basidiospores in Melzer’s reagent. 8. Cheilocystidia. 9. Pleurocystidia. Contents of cystidia are represented as observed in Congo Red for some elements only, the others are simply filled with dots to indicate their cystidial nature. Scale bar equals 10 μm, but only 5 μm for spores. Drawings by S. Jančovičová.