MycoBank: 818558

Diagnosis:—The shorter spore length of this new species clearly distinguishes it from other Gyrodon species, except G. minutus. However, this species has larger basidiomes and wider spores than G. minutus.

Etymology:— suthepensis refers to Doi Suthep-Pui National Park, where the holotype of the new species was found.

Holotype:— THAILAND, Chiang Mai Province, Muang District, Doi Suthep-Pui National Park, Medicinal Plant Garden (18°48’20”N 98°54’52”E, elevation 1075 m), under Betula alnoides in a tropical deciduous forest, June 15, 2012, Kumla J & Suwannarach N, SDBR-CMU55 I22, ITS sequence KX912272 and LSU sequence GenBank KX 912269.

Pileus 65−150 mm in diameter, convex to plano-convex, occasionally shallow and broadly depressed in the central with squamulose to radially felted tomentose when wet, greyish brown to greyish orange (5D3 to 5B2) at the central, slightly greyish orange to orange white near the margin (5B4 to 5A2) (Figure 4A), Margin inflexed to involute, yellowish white (4A2). Pileus context soft, yellowish white (4A2) slightly changing to slightly greenish blue (21E8) when exposed or bruised. Hymenophore tubulate, strongly decurrent. Tube short, 1−3 mm long, pale yellow to pastel yellow (2A3 to 2A4), becoming discolored to greenish blue (21E8) after bruising, Pores 0.5−1 mm in diameter, pale yellow becoming dull yellow with age (3A3 to 3B3), brushing to deep blue when exposed (21E8) becoming dark brown (6F5). Stipe 42−69 × 12−20 mm, solid, central sometime eccentric, cylindrical, slightly wider in middle or near the base, with brown (6E8) to dark brown (6F8) venose especially near the base, orange white (5A2) to slightly grayish orange (5B3) to brownish grey (5C2) near the base. Stipe context soft, orange grey (5B2) to pale orange (5A3) near the base, slightly changing to slightly greenish blue (21E8) when exposed or bruised. Spore print brownish orange. Macrochemical reactions; KOH, pinkish orange on pileus, stipe and context and tubes; NH 4 OH pinkish orange on pileus and stipe, yellow on tubes.

Basidiospore 3.5−5.5 × 2.5−4 μm, Q = 1.14−1.67, Q = 1.35 ± 0.25, subglobose to broadly ellipsoid, smooth, thin-walled, inamyloid (Figure 4B). Basidia 16−34 × 5.5−9.5 μm, narrowly clavate, hyaline, 4-spored, sterigmata 1.5−2.5 μm long (Figure 4C). Pleurocystidia 22−40 × 4.5−12 μm, tapering apex, narrowly fusiform to fusiform slightly wider in the middle to upper half, smooth, thin-walled, hyaline (Figure 4D). Cheliocystidia 22−59 × 5−12 μm, similar to pleurocystidia in shape (Figure 4E). Pileipellis 57−97 μm thick, with cylindrical, thin-walled, smooth, hyaline element of 3−8.5 μm in diameter, clamp connections present.

Ecology and distribution: Fruiting solitary or gregarious on soil during the rainy season under Betula alnoides. Known only from Thailand.

Additional collections examined: THAILAND, Chiang Mai Province, Muang District, Doi Suthep-Pui National Park, Medicinal Plant Garden, (18°48’20”N 98°54’52”E, elevation 1075 m), under Betula alnoides in a tropical deciduous forest, June 13, 2013, Vadthanarat S., Kumla J. & Suwannarach N., SDBR-CMUSV008; same locality, June 22, 2014, Kumla J. & Suwannarach N., SDBR-CMU56 I54.

Notes: Gyrodon suthepensis resembles G. lividus but the tubes of G. lividus has become to a dingy reddish brown color after being bruised and has mostly longer spores (5.5−8 μm long) (Saccardo 1888; Hayward & Thiers 1984; Hongo 1989, Zhuang 2001; Sesli et al. 2015). The spore length of G. suthepensis resembles G. minutus, but G. minutus has smaller basidiomes (pileus 1−3 mm in diameter and stipe 0.6−1 × 3−4 mm) and narrower spores (4.5−7 × 2−2.5 μm) (Tai 1979).