Russula vinosa subsp. occidentalis Singer, Pap.

Adamčík, Slavomír, Jančovičová, Soňa & Buyck, Bart, 2015, Type-studies in American Russula subsection Decolorantes (Russulales, Basidiomycota), part II., Phytotaxa 231 (3), pp. 245-259 : 255

Russula vinosa subsp. occidentalis Singer, Pap. Michigan Acad. Sci. 32: 114. 1948. Figs. 28–36

≡ Russula occidentalis (Singer) Singer, Sydowia 11: 155. 1958.

Original description:—A subspecie typica differt magnitudine majore, colore magis ardesiaco-violaceo vel viridello in pileo, sporis majoribus spinis longioribus echinatis. America Borealis occidentalis .

Spores shortly ellipsoid, (10.4–)10.9–11.6(–11.9) × (8.2–)8.5–9.2(–9.4) μm, average 11.2 × 8.8 μm, Q=(1.17–)1.22– 1.32(–1.37), average Q=1.27, with an ornamentation of large, conical, distant [2–5 in a 3 μm diam. circle], amyloid spines of very variable height, 0.8–1.4 μm high, mainly isolated, some connected with rare line connections [0–1 in the circle], or fused in pairs or short chains [0–1(–2) in the circle]; suprahilar plage amyloid. Basidia (50–)54–62 × (12.5–)13.5–16.5(–18) μm, average 58 × 15 μm, 4-spored, clavate-pedicellate; basidiola first cylindrical, then narrowly clavate. Subhymenium pseudoparenchymatic. Lamella trama mainly composed of large sphaerocytes. Hymenial cystidia dispersed [ca. 350–450/mm 2], fusiform or rarely clavate, pedicellate, measuring (75–)87–112.5(–125) × 11– 14(–15.5) μm, average 100 × 12.5 μm, narrowing upward, usually not mucronate or appendiculate, yet sometimes with 2–11 μm long appendage, thin-walled or with slightly thickened walls (up to 1 μm), with heteromorphous to granular contents turning brown-gray in sulfovanillin. Cheilocystidia dispersed but very protruding (more than half of their length), ca. 74–122 × 8–12.5 μm, narrowing upward and often with up to 10 μm long appendage. Marginal cells poorly differentiated, measuring (13–)15–22(–27) × 4.5–7(–8) μm, average 18 × 6 μm. Pileipellis orthochromatic in Cresyl Blue, sharply delimited from the underlying sphaerocytes of the context, 70–90 μm deep, vaguely divided in a very loose and thin, 30–40 μm deep, but strongly gelatinized suprapellis of repent, intricate hyphal ends and primordial hyphae, gradually passing into a denser, 40–50 μm deep, less gelatinized subpellis of intricate, horizontally oriented hyphae, that are ca. 2.5–4.5 μm wide with occasionally inflated elements (5–8 μm wide). Acidoresistant incrustations on primordial hyphae present and distinct. Hyphal extremities near the cap margin often with some dispersed inclusions visible in Congo Red (similar to those observed in true pileocystidia but not coloring in sulfovanillin), less so toward the cap center where they are less flexuous-moniliform; terminal cells measuring (28–)33.5–51(–63) × 2.5–4.5(–5.5) μm, average 42 × 4 μm, somewhat smaller in the cap center, cylindrical and slender, moniliform or flexuous; subapical cells equally wide, mostly irregular, nodulose-flexuous, branched and intricate, less so in the cap center. Primordial hyphae mostly in clusters, long, thin-walled, not branched, two- to four-celled, with acidoresistant incrustations that turn pinkish red in sulfovanillin, optically empty in sulfovanillin; with terminal cells measuring (20–)25.5–40(–52) × 3–6(–7.5) μm, average 33 × 4.5 μm, usually subcylindrical or narrowly clavate to lageniform or fusiform. Trama composed of large sphaerocytes and rather numerous oleiferous hyphae that are 3.5–6(–8) μm wide and constricted on septa, without cystidioid hyphae. Clamp connections absent in all parts.

Examined material:— UNITED STATES. Idaho. Boundary Co., Pend d’Oreille National Forest, Copeland, 8 September 1922, L.E. Wehmeyer & C.H. Kauffman (MICH 5386, holotype).

Commentary:— Singer (1948) validly published the name of this subspecies and referred to his earlier publication ( Singer 1939) where he published a full description of this “geographic race” of R. vinosa Lindblad (1902: 57) from the Pacific coast and Rocky Mts. of the USA (Idaho and Oregon) based on Kauffman’s notes for a never published herbarium name “ R. solitaria ”. Singer’s brief Latin diagnosis (Singer 1948) distinguished this subspecies by the “bigger size, more slaty-violaceous to greenish cap, larger spores with longer spines, growing in North-West America” and is completed with additional notes on variability mostly referring to cap color and spores.

Singer (1958) recombined this subspecies at the rank of species, R. occidentalis (Singer) Singer. He never designated a type specimen in any of his publications on this taxon, but he labeled the specimen MICH 5386 as the type in a note he included inside the box of this specimen: “ Russula occidentalis (Sing.) Sing. … you can mark as type the collections from Idaho by Kauffman called R. solitaria by him and redescribed by me in 1939 as R. vinosa ”. This specimen is one of two referred to in his first description ( Singer 1939) adopted from Kauffman’s notes: “Copeland, Ida. 2 sept. leg. Kauffman. le 8 septembre …”. We are therefore designating here the specimen MICH 5386 collected by L.E. Wehmeyer & C.H. Kauffman in Copeland (Idaho) at 8 September 1922 as the lectotype.

Romagnesi (1967) included R. vinosa in Russula subsect. Integroidinae because it lacked sulfovanillin-positive elements in the pileipellis but possessed incrusted primordial hyphae and produced a yellow spore print. This subsection differs from Russula subsect. Amethystinae ( Romagnesi 1962: 172) Bon (1986: 53) by the presence of numerous “lactifers” in the stipe cortex, and from Russula subsect. Chamaeleontinae Singer (1932: 236) by the absence of clavate hyphal terminations in the pileipellis. Russula occidentalis has several characters in common with typical European R. vinosa and the type specimen possesses numerous oleiferous hyphae in the subpellis of the cap possibly corresponding to Romagnesi’s “lactifers” in stipe cortex. The current concept of this species ( Roberts 2007) is in agreement with this placement and supported by two ITS nrDNA sequences from recent collections deposited in GenBank.

Figures

FIGURES 28–30. Russula vinosa var. occidentalis (holotype). 28. Primordial hyphae at pileus surface as observed in Congo Red, two elements with incrustations seen after Carbol fuchsin treatment. 29. Hyphal extremities in the cap center. 30. Hyphal extremities near the cap margin. Scale bar equals 10 μm. Drawings by S. Jančovičová.

FIGURES 31–36. Russula vinosa var. occidentalis (holotype). 31. Basidia. 32. Basidioles. 33. Marginal cells. 34. Basidiospores in Melzer’s reagent. 35. Cheilocystidia. 36. Pleurocystidia. Contents of cystidia are represented as observed in Congo Red. Scale bar equals 10 μm, but only 5 μm for spores. Drawings by S. Jančovičová.