Russula carmesina R. Heim

Russula carmesina Heim, Rev. Mycol. (Paris) 34 (4): 347 (1970) Figs 11, 12, 13, 14 Holotype. Central African Republic. gallery forest along the Lobaye River, solitary, directly on the ground, 12. 05. 1968, leg. R. Heim, LM 3038 (PC 0798351). Additional material examined. Benin. Atakora, Natitingou, Kota waterfalls, co-ord. 10°12.7'N, 1°26.8'E, alt. 500 m, in a gallery forest, under Uapaca guineensis, directly along the riverside on bare sand, 11. 07. 2021, leg. C. Manz, F. Hampe, N. S. Yorou & G. Abohoumbo, CM-21-108 (B 70 0105417, UNIPAR); ibid. 19. 07. 2021, leg. C. Manz, F. Hampe, N. S. Yorou, G. Abohoumbo & D. Dongnima, CM-21-143 (B 70 0105418, UNIPAR); ibid. 05. 07. 2022, leg. C. Manz & F. Hampe, CM-22-282 (B 70 0105419, UNIPAR); Guinea. Kankan, National Park of Upper Niger, co-ord. 10°14.8'N, 10°27.8'W, under Isoberlinia doka, Anthonotha fragrans (Baker f.) Exell & Hillc., Anthonotha crassifolia (Baill.) J. Léonard & Uapaca togoensis, 07. 08. 2022, leg. N. S. Yorou, SYN 5103 (UNIPAR). Short description. Very small basidiomata, pileus surface bright red, lamellae edges partly reddish, stipe narrowing towards the frequently reddish base, pileipellis a hymeniderm, occurring in gallery forests. Description based on material recently collected in Benin and Guinea. Growth habit: basidiomata solitary or in small groups of approx. ten. Pileus: very small to small, 3–12 mm in diam., when young, hemispherical, later convex, expanding plane, centrally depressed; margin even, frequently finely radially cracked up to 3 mm, when young with a very fugitive, pale, veil-like overhanging membrane that is not reaching the stipe, when mature, visible as very fine scales, giving a slightly uneven appearance, never forming an annulus; cuticle smooth, matt, finely radially fibrous, somewhat velvety, peelable up to ½ of the pileus radius, partly descending on to the lamellae edges, colour when young, blood red (10 C 8), later cherry red (10 B 8), lake red (9 C 8) or lobster red (9 B 8), sometimes paler towards the margin: red (9 A 6) or pastel red (9 A 5). Lamellae: 1–2 mm wide, 10–11 lamellae present along 1 cm near the pileus margin, ventricose, adnexed, sometimes with a decurrent tooth, white, furcations, anastomoses and lamellulae absent, edges entire, white or frequently red near the pileus margin. Stipe: 5–15 × 2–3 mm, cylindrical or frequently narrowing towards the base; smooth to slightly rugose, annulus absent, white, covered partly also with a pastel red (9 A 4) hue at the base or the entire stipe; cottony stuffed. Context: only up to 0.5 mm thick at half pileus radius, white, unchanging when bruised, very fragile, taste mild, odour inconspicuous; macrochemical reactions: guaiac after 8–10 seconds negative (-) on both stipe and lamellae surfaces, sulphovanillin negative, FeSO 4, KOH and phenol not tested. Spore print: white (Ia). Spores: (6.9 –) 7.9–8.4 – 8.8 (– 9) × (6.6 –) 7.5–7.9 – 8.4 (– 9) µm (n = 61), Q = (1 –) 1.02–1.05 – 1.09 (– 1.15), globose to subglobose; ornamentation of distant to moderately distant amyloid spines [2–4 (– 6) in a circle of 3 µm diam.], 1–2 µm high, connected by numerous lines [2–4 (– 5) in the circle] forming a complete reticulum, spines occasionally fused in pairs (0–2 fusions in the circle), tips frequently bifurcate as seen by SEM; suprahilar plage moderately large, inamyloid, without ornamentation. Basidia: (28 –) 33.5–37.5 – 41.5 (– 46) × (10 –) 11–12 – 13 (– 14.5) µm (n = 40), clavate to broadly clavate, 4 - spored; basidiola approx. 5–8 µm wide, cylindrical or clavate. Hymenial cystidia: on lamellae sides (51 –) 60–71 – 82 (– 88) × (8 –) 10–13 – 15 (– 20) µm (n = 40), widely dispersed, 60–130 / mm 2, narrowly to broadly clavate, rarely subcylindrical, originating in subhymenium and somewhat protruding over basidia, thin-walled, apically obtuse, with or without one or two 1.5–15 µm long appendages; heteromorphous contents abundant, crystalline to amorphous, mostly located in the upper half, turning distinctly greyish-black in sulphovanillin after 2–3 minutes. Hymenial cystidia near the lamellae edges distinctly shorter, (28.5 –) 32–37.5 – 43.5 (– 53.5) × (9 –) 10.5–11.5 – 12.5 (– 14) µm (n = 40), clavate to broadly clavate, rarely slightly constricted, occasionally with a 1.5–4 µm long appendage; heteromorphous contents similar to the one in hymenial cystidia on lamellae sides. Lamellae edges: fertile, with equal representation of cystidia, basidia, basidiola and marginal cells. Marginal cells: (11 –) 13–16.5 – 19.5 (– 26) × (5 –) 6–7.5 – 8.5 (– 10.5) µm (n = 40), predominantly fusiform with acute apex, sometimes ovoid with obtuse apex, optically empty, thin-walled. Pileipellis: orthochromatic in Cresyl blue, gradually passing to the underlying context, not gelatinised, 50–70 µm deep; suprapellis a hymeniderm or epithelium, 20–27 µm deep, composed of one or two layers of inflated terminal cells; sharply delimited from a 20–37 µm deep subpellis of moderately dense, horizontally orientated, 2.5–4 µm wide interwoven hyphae. Acid resistant encrustations absent. Hyphal terminations: near the pileus margin usually composed of single or sometimes two cells before branching, thin-walled; terminal cells (11.5 –) 14.5–18 – 21.5 (– 26.5) × (3.5 –) 7–9.5 – 12 (– 14.5) µm (n = 60), predominantly ovoid or clavate to broadly clavate with obtuse apex, frequently also fusiform with pointed apex, rarely cylindrical; subterminal cells distinctly shorter, more or less isodiametric, 3–10 µm wide, mainly branched. Hyphal terminations near the pileus centre similar to the ones near the pileus margin, terminal cells (7 –) 11–14 – 17 (– 21.5) × (5 –) 7–9.5 – 12 (– 17) µm (n = 60), globose to subglobose or ovoid with obtuse apex; subterminal cells almost exclusively branched. Pileocystidia: near the pileus margin (16.5 –) 17–22 – 27 (– 40.5) × (6 –) 7–8.5 – 9.5 (– 11.5) µm (n = 40), one-celled, cylindrical to broadly clavate, rarely base-inflated, originating in the suprapellis, thin-walled, apically obtuse, without appendages; heteromorphous contents dense, crystalline to amorphous, present in the entire cell, turning distinctly greyish-black in sulphovanillin after 2–3 minutes. Pileocystidia near the pileus centre distinctly shorter, (12 –) 15–19 – 23 (– 28.5) × (4 –) 6.5–8 – 9.5 (– 11.5) µm (n = 40), globose to ovoid, clavate or broadly cylindrical; contents similar to the one in pileocystidia near the pileus margin. Context: very thin in pileus, consisting of a layer only 1–2 sphaerocysts thick; cystidioid and oleiferous hyphae absent. Distribution and ecology. Known from gallery forests in Guinea, Benin and Central African Republic. Notes. In the past, Russula carmesina was placed in subsect. Pseudoepitheliosinae together with several other species with small basidiomata and a hymenidermal pileipellis structure, predominantly distributed in Africa (Buyck 1990 b). It is very similar to Russula parasitica (R. Heim) Buyck and Russula pseudocarmesina Buyck; however, these two species are distinctly annulate (Buyck 1994). In addition, R. pseudocarmesina has larger basidiomata with pileus diameters of 2–4 cm (Buyck 1994). Russula pseudoepitheliosa Buyck is a similar species without annulus, but also has larger basidiomata with purplish-violet pileus colours (Buyck 1994). In the original description of R. carmesina, Heim did not mention the presence of pileocystidia, although he was usually mentioning these elements in his other Russula descriptions when he observed them (Heim 1970). As the holotype material was lost for decades, R. carmesina was thought to be lacking pileocystidia and the placement in subsect. Pseudoepitheliosinae was uncertain (Buyck 1990 b). Fortunately, we were able to locate the type material. It was in a bad condition, since it was previously stored in ethanol which evaporated a long time ago, leaving a miniscule, blackish remnant of a basidioma encrusted by crystalline matter. However, by microscopic investigation, the presence of obvious pileocystidia in the material could be revealed (Fig. 14).