Suillus kovalenkoi Zvyagina & Sazanova, 2025

Zvyagina, Elena A. & Sazanova, Nina A., 2025, Suillus kovalenkoi (Boletales, Agaricomycetes), a new Larix-associated species from North Asia, Phytotaxa 702 (3), pp. 231-254 : 242-244

Suillus kovalenkoi Zvyagina & Sazanova , sp. nov., Figure 3B–F , 4 A .

MycoBank MB 843344

Type:— RUSSIAN FEDERATION. Magadanskaya Oblast’ : Susumanskiy Rayon, Susuman vicinities, 62.83°N, 148.25°E, larch ( Larix cajanderi Mayr (1906: 297) forest with the lingonberry groundcover at the base of a slope with steppe vegetation, 21 August 2018, N. Sazanova (holotype: MAG 5111 !; GenBank OM780293 - ITS, OM780311 - LSU, OM807067 - TEF 1 α).

Diagnosis:— Basidiomata boletoid, medium to large. Pileus viscid, glabrous, bright yolk-yellow, spotted brick-red in age. Pores angular, wide, different in size, decurrent, yellowish white with a gray tint, discolouring purple-gray when bruised; tubes purple-gray. Context yellow, bluing first when cut, then fading to fuscous. Stipe covered with decurrent hymenophore at apex and smooth below the ring, yellow in upper part and brownish yellow in lower part, discolouring with bluish-fuscous spots when bruised. Velar ring double, thick, membranaceous, glutinous, yellow then red brownish on the outside and whitish towards the stipe.

Etymology:—This new species is named in honour of the great mycologist Alexander Eliseyevitch Kovalenko, in memory of a dear mentor and colleague.

Description:— boletoid. Pileus: 3–8(17) cm diam, convex, flattening with age. Margin with appendiculate remnants of the partial veil. Surface viscid when wet, glabrous, bright yolk yellow (R246G284B60), golden-yellow (R225G241B19), later spotted brick-red. Mucus turning slightly brick-red in the air and drying reddish. Pores 1–2 mm wide, angular, different in size, decurrent, yellowish white (R252G244B188) with a gray tint (R252G244B188), discolouring purple-gray when bruised (R252G244B188); tubes purple-gray. Context fleshy, yellow, sometimes bluing first when cut, and then fading to fuscous. Stipe: 7–11(13) × 1.5–4(7) cm, cylindrical, central. Surface yellow above the ring and brownish-yellow in the lower part, in some collections discolouring with bluish-fuscous spots when bruised. Velar ring double, prominent, thick, membranaceous glutinous and yellow then red brownish in the upper part, and whitish yellow in the lower part. Inner layer whitish. Context fleshy, white-yellow, golden-yellow, bruising brownish in young specimens, occasionally exhibiting a blue-green discolouration in mature specimens. Taste and odour indistinct to pleasant mushroomy. Spore print brownish.

Basidiospores: (8.1–)9.6–14.1(–17.6) × 4.2–5.4(–7.1) μm, Q=(1.9–)2.0–2.8(–3.0), Qm=2.4±0.2 elongate to oblong-ellipsoid, ovoid, inequilateral in profile, moderately thick-walled, pale brown, smooth. Basidia: (20.4–)24.8– 28.6(–37.6) × (5–)5.9–8.9(–11.2) μm, four-spored, clavate to subclavate, hyaline or with yellowish brown context in KOH. Cystidia: (31.0–)51.5–89.3(–112.7) × (5.8–)6.8–11.5(–16.8) μm, cylindrical and slightly widened to clavate in the upper part, with ochre-yellow context in KOH or sometimes hyaline, arranged in fascicles, sometimes incrusted with a yellow gelatinous substance; cheilocystidia in dense clusters along the tube margin, pleurocystidia in small groups sometimes covered with gelatinous substance abundant all over the tube inner surface, cheilocystidia and pleurocystidia similar in shape and size. Pileipellis: an ixotrichoderm consisting of (2.2)3–6.7(–8) μm wide hyphae with sparse septa. Mucus on the pileipellis surface slightly reddening in the Melzer’s. Stipitipellis: the gelatinous layer of the mixed basidiole-like cells and interwoven hyphae, sometimes condensed into brownish tubercles. Clamp connections not observed.

Distribution and habitat:— In groups in conifer and mixed forests among mosses and dwarf shrubs, ectomycorrhizal with Larix sibirica Ledeb. (1833: 204) and L. cajanderi . Russia (Eastern Siberia and Far East). Common edible mushroom.

Additional specimens examined:— Paratypes: RUSSIA. Irkutskaya Oblast’: Bratskiy Rayon, Kob’, 55.43°N, 101.37°E, mixed forest with Picea abies (L.) H. Karst. (1881: 325). and L. sibirica and feather mosses, August 1977, N. Kutaf ’yeva (LE 4766!); ibid., mixed forest with P. abies and L. sibirica , 13 August 1983, A. Kovalenko (LE 18421!); ibid., mixed forest with L. sibirica , 15 August 1983, A. Kovalenko (LE 18056!); ibid., 22 August 1983, A. Kovalenko (LE 18089!; GenBank MK573965 -ITS); Magadanskaya Oblast’: Ten’kinskiy Rayon, Elochka, Orotuk, 62.06°N, 148.64°E, larch forest ( L. cajanderi ) with dwarf shrubs and lichens, 07 August 1997, N. Sinelnikova (MAG 1307!; GenBank OM780309 -LSU); ibid., Srednekanskiy Rayon, Seymtchan village vicinities, 62.92°N, 152.29°E, 14 August 1999, N. Sazanova (MAG 1308!; GenBank OM780308 -LSU); ibid., Khasynskiy Rayon, Ola river upper riches, 60.65°N, 151.25°E, larch forest ( L. cajanderi ) with dwarf shrub and feather mosses, 02 August 2001, E. Adriyanova (MAG2642!; GenBank OM780310 -LSU, OL542657 -TEF 1α).

Other collections examined:

Ix. flavus f. caerulescens :— RUSSIA. Altai Republic: Kosh-Agachskiy district, southwest of Oktura , 1800-2000 m, 5 August 1937, R. Singer ( LE 4554 (592)!); ibid., August 1937, R. Singer & L. Vasilieva ( LE 4547 (512)!)

S. bresadolae var. flavogriseus :— ITALIA. Trentino Alto Adige: Frassilongo, 1600 m. G. Consiglio & G. Simonini, GS1844 (MCVE 18244!).

S. gastroflavus :— RUSSIA. Magadan Region: Srednekansky district, vicinity of Seimchan village, valley of Kolyma river , 62.83°N, 152.43°E, 28 September 2018, N. Sazanova (paratype MAG 5122 !, GenBank MK572961 - ITS) ; ibid., valley of Seimchanka river, 62.96°N, 152.34°E, 15 August 2010, N. Sazanova (holotype MAG 3480 !, and sequences GenBank MK572960 - ITS, MK607461 - LSU) .

Notes: — Vivid yellow pileus, robust double mucous and membranaceous yellow-brown ring or thick remnants of the partial veil along the pileus margin, which remain clearly visible in dried specimens, brick-red spots, which develop on the pileus as it ages, and the gray tubes, coupled with the association with Larix , set this species apart from the others.

Morphological affinities: — S. bresadolae f. flavogriseus , S. gastroflavus , S. moseri , S. grevillei display yellow tinted basidiomata and all are associated with Larix .

Figures

FIGURE 3. Suillus kovalenkoi Zvyagina & Sazanova, sp. nov. A natural habitat, B basidiomata in situ MAG 1307 (paratype), photo by M.N. Pakhomov, C basidiomata in situ MAG 5111 (holotype), D basidiospores, E Pileipellis, F Pleurocystidia. Scale bars: B, C 1 cm, D, E 10 μm, F 20 μm.

FIGURE 4. Pileipellis structures in Congo Red. A S. kovalenkoi holotype (MAG 5111); B Suillus nueschii var. caerulescens (LE 4547); C S. bresadolae var. flavogriseus (MCVE 18244); D S. gastroflavus paratype (MAG 5122). Scale bars 10 μm.