Pholiotina sphagnicola T. Bau & Burenbaatar G., sp. nov.

Pholiotina sphagnicola T. Bau & Burenbaatar G., sp. nov. (Figure 2 and 3)

MycoBank number:— 851517

Diagnosis: — Pholiotina sphagnicola can be easily distinguished from its close relative, Ph. arrhenii, since Ph. sphagnicola has 2(1)-spored basidia with sterigmata measuring 3–13 μm in length, resembling rabbit ears; additionally, the basidiospores of Ph. sphagnicola are 11.6–15.7 μm. In contrast, Ph. arrhenii has 4-spored, with a length of 6–9 μm.

Etymology: — “ sphagnicola ” refers to inhabits in spahagnum.

Type: — MONGOLIA. Khentii Province, Cenxermandal Sum, Khar Zurkhnii Khukh Nuur, alt. 1675 m, 108° 57′ 0″ E, 48° 2′ 0″ N, 4 August 2023, Tolgor Bau and Burenbaatar G., 3I42 (HMJAU 64971, holotype!).

Description: —Pileus 0.5–2 cm wide, hemispherical, convex, slightly elevated in the center, somewhat conical, center orange brown (RAL8023) to copper brown (RAL8004), transitioning to lighter colors towards the edges, ranging from beige (RAL1001) to ivory (RAL1014) and light ivory (RAL1015), non-sticky with indistinct or absent striae on the margin. Context thin, ivory (RAL1014) to sand yellow (RAL1002), with no special smell. Lamellae narrowly adnate, ventricose, moderately crowded, of unequal length, ranging from beige (RAL1001), ivory (RAL1014), sand yellow (RAL1002) to ochre brown (RAL8001), with a serrated margin. Stipe 2.0– 4 cm long and 0.15–0.3 cm thick, cylindrical, gradually widening towards the base, ranging from ivory (RAL1014) to light ivory (RAL1015) and sand yellow (RAL1002), surface has longitudinal fibrous stripes. Above the ring, the stipe is slightly frosted, and below the ring, it has small tufts of hair. The ring was superior and membranous, matching the color of the stipe, with wavy grooves on its upper surface.

Basidiospores(60/3/2)(11.1–)11.6–15.7(–16.8)×(6.1–)6.4–8.7(–9)μm,Q=(1.56–)1.66–2(–2.21),Q m =1.81(±0.11), oblong, thick wall, containing oil droplets, germination pore diameter can reach up to 2 μm, spores turn reddishorange (RAL2001) to copper-brown (RAL8004) in 5% KOH solution. Basidia (17–)18–34(–36) × (7–)8–11(–12) μm, broadly clavate to clavate, 2(1)-spored, sterigmata 3–13 μm long, resembling rabbit ears, and basidia with vacuolar contents. Cheilocystidia (15–)16–39(–44) × (6–)7–10(–11) μm, ranging from lageniform to narrowly lageniform, subcylindrical, and lanceolate, some have slightly enlarged tips and appear spheropedunculate to globose, with sterile lamellar edges. Pleurocystidia absent. Caulocystidia in the upper part of the ring (17–)19–39(–45) × 6–11 μm, similar to cheilocystidia, range from lageniform to narrowly lageniform, subcylindrical, and lanceolate, some had slightly enlarged tips and appeared spheropedunculate to globose, resembling a hair-like structure. Pileipellis hymeniform, consisting of sphaeropedunculate elements, 19–29(–30) × (10–)11–17 μm, in 5% KOH solution, the base exhibits a brownish-red (RAL3011) pigment. Pileocystidia absent. Slightly thin gelatinous layer. All structures had clamped connections. Ammoniacal reaction was negative.

Habitat: —Grows in clusters on sphagnum and moist grassy moss layers.

Distribution: —It is only known in Mongolia, Khentii Province, Cenxermandal Sum, and Khar Zurkhnii Khukh Nuur.

Additional specimen examined (paratype): — MONGOLIA. Khentii Province, Cenxermandal Sum, Khar Zurkhnii Khukh Nuur, alt. 1670 m, 108° 57′ 3″ E, 48° 2′ 10″ N, 4 August 2023, Tolgor Bau and Burenbaatar G., 3I42-1 (HMJAU64972).