Pluteus flammans Polhorský, Ševčíková, Justo, Fedor & Dima, 2023

Polhorský, Adam, Justo, Alfredo, Szabóová, Dana, Konyariková, Zuzana, Dima, Bálint & Ševčíková, Hana, 2023, Pluteus flammans, a new brightly coloured species in Pluteus sect. Celluloderma (Pluteaceae) from Central Europe, Phytotaxa 598 (1), pp. 69-79 : 72-76

Pluteus flammans Polhorský, Ševčíková, Justo, Fedor & Dima sp. nov., Figs. 2 , 3

MycoBank:—MB 847337

Etymology:— flammans (Latin) = flaming, burning. Refers to the bright reddish, yellow-orange colour of the basidiomata.

Diagnosis:—A brightly coloured species with a trichodermal pileipellis in Pluteus sect. Celluloderma . Similar to P. aurantipes , but differing in the colours of the pileus and stipe, basidiospores (smaller), caulocystidia (shorter), geographic distribution, and ITS and TEF1-α sequences.

Description:— Basidiomata scattered to subgregarious, growing individually or in small groups of up to 5 basidiomata. Pileus 8–26 mm diam, convex, campanulate, becoming plano-convex to applanate, with distinct umbo; translucently striate at the margin and up to half the pileus diam.; surface villose with abundant scales at the centre, becoming less frequent towards the edge; margin only finely pubescent; yellowish orange, orange-red to orangebrown, darker at the centre. Lamellae free, moderately crowded, broad, light yellow-orange; edge whitish, slightly pubescent. Lamellulae present. Stipe 10–20 × 2–3 mm, cylindrical, slightly broadened at the base or not, fibrillose, entirely pubescent when young, later mainly at lower half, remaining tomentose at base, yellow-orange, concolorous with pileus, paler towards top. Context yellowish. Odor indistinct, taste not observed.

Basidiospores [245, 7, 7] (4.0–)5.2–6.3(–7.5) × (3.5–)4–4.7(–5.3) μm, Lav × Wav = 5.4–5.9 × 4.1–4.4 µm, Q = (1.08–)1.23–1.41(–1.56), avQ = 1.3–1.33, subglobose to ellipsoid, rarely subovoid, ± thick-walled; lipid content granular in living basidiospores, coalescing into larger guttule(s) in more mature or dead basidiospores. Basidia 17–29 × 6.0–10.0 μm, 4-spored, narrowly clavate to clavate, sometimes with median constriction. Basidioles 14–25 × 4.8– 10.5 μm, narrowly to broadly clavate. Pleurocystidia absent. Cheilocystidia (18.0–)26–43(–55) × (6.5–)9.5–14.5(–21) μm, abundant, forming sterile layer at lamella edge, narrowly to broadly clavate, narrowly lageniform to lageniform or subfusiform, rarely subutriform, with rounded apex, hyaline, rarely containing large yellow to yellowish brown vacuole(s), thin-walled. Pileipellis a trichoderm, composed of cylindrical or narrowly fusiform elements, with yellow to yellow-orange to brown intracellular pigment, 29–160 × 6.4–31 μm. Stipitipellis a cutis, made up of long cylindrical hyphae, 24–200 × (1.8–)5.0–20 μm, containing yellow, yellow-orange vacuole(s). Caulocystidia abundant, 19–115 × 5.9–14 μm, cylindrical to narrowly clavate or narrowly subfusiform, appearing in clusters or solitary, thin-walled, with or without yellow to orange intracellular pigment. Crystal druses sometimes present in pileipellis, stipitipellis and among cheilocystidia. Clamp connections absent in all tissues.

Ecology and distribution:—Known from Slovakia and Hungary on fallen, strongly rotten Quercus spp ., e.g., Q. cerris L. (1753: 997), trunks and logs in lowland and hilly xerothermophilous Pannonian oak groves; in beech or hornbeam forests on Fagus sylvatica L. (1753: 998) and Tilia sp. rotting trunks and branches near streams.

Holotype:— SLOVAKIA. Bratislava,. Senec, Martinský les, very rotten Quercus sp. trunk, N48.25634° E17.38136°, elev. 155 m, 20 August 2020, A. Polhorský (holotype BRNM 829078 , ITS sequence GenBank OQ331563 ; TEF1-α OQ332374 , MycoBank MB 847337 ).

Additional material examined:— SLOVAKIA. Bratislava, Senec, Martinský les, very rotten Quercus sp. trunk., N48.2467°, E17.3649°, elev. 172 m, 21 May 2022, A. Polhorský, BRA CR36322 ; N48.2468° E17.36715°, elev. 170 m, 11 June 2022, A. Polhorský, BRA CR36323 ; Prešov, Snina, Trstená , mossy, rotten Tilia sp. branch, elev. 280 m, 16 July 2013, J. Pavlík, BRA CR25862 ; ibid., 30 July 2013, J. Pavlík, BRA CR25868 ; Zemplínske hámre, Čierny potok, mossy, very rotten, possibly a Fagus sylvatica trunk, elev. 490 m, 5 August 2013, J. Pavlík, BRA CR25908 ; Košice, Brezina, Izra , very rotten Fagus sylvatica trunk, elev. 450 m, 7 August 2020, M. Lazor, BRA CR35417 ; Trnava, Hubina, Salaška , rotting remains of Quercus sp. trunk, elev. 220 m, 13 June 2016, M. Villaris, BRA CR35418 ; HUNGARY. Pest, Budakeszi, Szarvas-árok , on old, decaying Quercus sp. trunk, N47.3181°, E18.5346°, elev. 320 m, 19 June 2018, I. Fedor & B. Dima, DB- 2018-06-19 ( ELTE) ; Borsod-Abaúj-Zemplén, Miskolc, Köpüs-völgy , on old, decaying Quercus cerris log, 16 August 2021, G. Pelles, DB- 2021-08-16 ( ELTE).

Figures

FIGURE 2. Pluteus flammans basidiomata. a, c. BRA CR25862; b. BRA CR25908; d. BRA CR25868; e, g., BRA CR36322; f. BRNM 829078 (holotype). Scale bars: a, c–e = 2 mm; b, f, g = 5 mm. Photos a–d: Jozef Pavlík; e–g:Adam Polhorský.

FIGURE 3. Pluteus flammans microscopy (BRNM 829078–holotype). a, c. basidiospores from spore print; b, d. basidia and basidioles; e–g. cheilocystidia; h. stipitipellis; i. crystal druses in pileipellis; j. caulocystidia; k, l. pileipellis elements (a, b, e–i, k, l. in tap water; c, j. in KOH; d. in CR). Scale bars: a, c = 5 μm, b, d–l = 10 μm. Photos: Adam Polhorský.