Russula hiemisilvae Buyck

Manz, Cathrin, Amalfi, Mario, Buyck, Bart, Hampe, Felix, Yorou, Nourou S., Adamčík, Slavomír & Piepenbring, Meike, 2025, Just the tip of the iceberg: uncovering a hyperdiverse clade of African Russula (Basidiomycota, Russulales, Russulaceae) species with signs of evolutionary habitat adaptations, IMA Fungus 16, pp. e 140321-e 140321 : e140321-

Russula hiemisilvae Buyck , Karstenia 33: 27 (1993)

Figs 21 , 22 , 23

Holotype.

Tanzania. Western Province, Kahama District, 30 km W of Kahama, Wendele, Forest Reserve (03 32 CB) , alt. 1,200 m, on soil in Brachystegia Benth. - Combretum Loefl. woodland, 09. 12. 1991, leg. Saarimtiki et al. 1028 (H 7041854) .

Additional material examined.

Benin. Atakora, Kossoucoingou , co-ord. 10°9.9'N, 1°12.1'E, alt. 500 m, Sudanian woodland, under Isoberlinia tomentosa , on rocky soil, 20. 07. 2021, leg. C. Manz, F. Hampe, G. Abohoumbo, T. C. Bogo, CM-21-150 ( B 70 0105430 , UNIPAR) .

Short description.

Russula hiemisilvae is a rather robust, mild, annulate species with a greyish-red pileus, stipe with rose hue and ellipsoid spores with a reticulate ornamentation with spines up to 1.5 µm high, occurring in savannah woodlands.

Description based on material recently collected in Benin.

Growth habit: basidiomata in small groups. Pileus: medium-sized, 50–55 mm in diam., plane, slightly centrally depressed; margin even, striate up to 15 mm, regularly shaped, finely crenulate; cuticle smooth, radially fibrous, slightly shiny, peelable up to ½ of the pileus radius, colour near the margin pinkish-white (11 A 2), pale red (11 A 3) or greyish-rose (11 B 3), near the centre, dull red (11 C 3–4), greyish-brown (11 D 3) or greyish-red (11 D 4), sometimes with lighter spots. Lamellae: 5–6 mm wide, 7–8 lamellae present along 1 cm near the pileus margin, narrowly adnate, white, furcations, anastomoses and lamellulae absent; edges, concolourous. Stipe: 40–45 × 12–15 mm, cylindrical, sometimes narrowing towards the base, slightly bulging here and there; smooth to slightly rugose, with a fugacious white and dull red (11 C 3–4) rimmed annulus, white with a rose hue; cottony stuffed. Context: 1 mm thick at half pileus radius, white, unchanging when bruised, brittle, taste mild, odour inconspicuous; macrochemical reactions: guaiac after 8–10 seconds positive (++) on both stipe and lamellae surfaces, FeSO 4 rose, sulphovanillin negative, KOH discolouring red parts to yellow, phenol negative. Spore print: not observed, but probably white or cream.

Spores: (8.3 –) 8.6–9 – 9.4 (– 9.9) × (7.3 –) 7.5–7.7 – 7.9 (– 8) µm (n = 30), Q = (1.08 –) 1.13–1.17 – 1.22 (– 1.26), subglobose to broadly ellipsoid; ornamentation of moderately distant amyloid spines [3–6 (– 7) in a circle of 3 µm diam.], 1.1–1.5 µm high, connected by abundant, distinct lines [3–6 (– 7) in the circle], forming a complete reticulum with regularly-shaped meshes, isolated elements absent; suprahilar plage small, inamyloid, without ornamentation, surrounded by small warts. Basidia: (41.5 –) 44.5–49 – 53.5 (– 59) × (12 –) 13–13.5 – 14 (– 14.5) µm (n = 20), subclavate to clavate, 4 - spored; basidiola approx. 7–9 µm wide, clavate to subclavate. Hymenial cystidia: on lamellae sides (70.5 –) 77–86 – 95.5 (– 101) × (11 –) 12–13.5 – 15 (– 16) µm (n = 20), widely dispersed, 27–82 / mm 2, cylindrical to subclavate, sometimes slightly constricted, originating in subhymenium and somewhat protruding over basidia, thin-walled, apically obtuse, with a 2–7 (– 9) µm long appendage; heteromorphous contents dense, amorphous, mostly located in the upper half, turning distinctly dark yellow-brown in sulphovanillin. Hymenial cystidia near the lamellae edges shorter and narrower, (52.5 –) 56–61 – 66.5 (– 73.5) × (9 –) 10–11.5 – 13 (– 14.5) µm (n = 20), predominantly fusiform, with a 1.5–8 µm long appendage; heteromorphous contents less dense and less frequently located in the upper half. Lamellae edges: fertile, marginal cells intermixed with basidia and basidiola. Marginal cells: (30 –) 33–38 – 43 (– 46) × (3.5 –) 5.5–6.5 – 8 (– 9) µm (n = 20), cylindrical to subclavate with frequent irregular constrictions, frequently flexuous, optically empty, thin-walled. Pileipellis: orthochromatic in Cresyl blue, well delimited from the underlying context, 135–200 mm deep; suprapellis 50–110 µm deep, of loose, irregularly orientated hyphal terminations embedded in a gelatinous matrix; sharply delimited from a 70–85 µm deep subpellis of dense, parallel, 2.5–4.5 µm wide hyphae, with cystidioid hyphae with crystalline contents. Acid resistant encrustations absent. Hyphal terminations: near the pileus margin composed of 1–2 (– 3) unbranched cells, thin-walled, terminal cells (16.5 –) 22–26 – 30 (– 33) × (3 –) 3.5–4 µm (n = 30), cylindrical or slightly narrowing towards the apex, rarely subcapitate, apically obtuse, rarely acute; subterminal cells shorter, sometimes isodiametric, 3–4.5 µm wide, cylindrical. Hyphal terminations near the pileus centre of 1 (– 2) unbranched cells, thin-walled, terminal cells (6.5 –) 12–19 – 26 (– 33) × (2.5 –) 3.5–4 – 5 (– 6) µm (n = 37), irregularly shaped, cylindrical or subulate, frequently with several constrictions or branched, apically obtuse; subterminal cells usually shorter, 3.5–7.5 µm wide, cylindrical or ellipsoid, often irregularly shaped and with lateral branches or nodes. Pileocystidia: near the pileus margin (21 –) 24–31.5 – 39 (– 45.5) × (3.5 –) 4–4.5 – 5.5 (– 6) µm (n = 20), one-celled, lanceolate, cylindrical or subclavate, originating in the suprapellis, thin-walled, occasionally with a 2–3 µm long appendage or terminal knob; heteromorphous contents amorphous, weakly turning grey-violet in sulphovanillin. Pileocystidia near the pileus centre similar in size and shape to the ones near the pileus margin, (21.5 –) 25.5–29.5 – 33.5 (– 39.5) × (3.5 –) 4.5–5.5 – 6.5 (– 7.5) µm (n = 20), more frequently with a 2–4 µm long appendage or terminal knob; heteromorphous contents similar. Context: without cystidioid and oleiferous hyphae.

Distribution and ecology.

Widely distributed in tropical African savannah woodlands. Known from Benin, Burundi, Madagascar, Tanzania, Zambia and Zimbabwe.

Notes.

The material of R. hiemisilvae from Benin was identified, based on type sequencing. The holotype material of R. hiemisilvae differs from our collection by the presence of refractive inclusions in the hyphal terminations in the pileipellis and the reddish to almost absent reaction of the cystidia to sulphovanillin ( Härkönen et al. 1993). Russula annulata is a similar annulate species described from Madagascar, which differs from R. hiemisilvae by a stipe covered by vivid violet pustules, lamellae with dark violet edges and violet context under the cuticle ( Heim 1937, 1938).

Figures

Figure 21. Russula hiemisilvae (CM- 21-150) A field picture of basidiomata, B scanning electron microscopical picture of basidiospores. Scale bar: 2 cm (A); 3 µm (B).

Figure 22. Hymenial elements of Russula hiemisilvae (CM- 21-150) A basidia and basidiola, B hymenial cystidia near the lamellar edges, C marginal cells, D hymenial cystidia, E spores as seen in Melzer’s reagent. Scale bar: 10 μm, but only 5 μm for spores.

Figure 23. Elements of the pileipellis of Russula hiemisilvae (CM- 21-150) A, B elements near the pileus centre: A hyphal terminations, B pileocystidia; C, D elements near the pileus margin: C hyphal terminations, D pileocystidia. Scale bar: 10 μm.