Scleroderma magnisporum Gonkhom, Sysouph. & Thongkl. 2025, sp. nov.

Scleroderma magnisporum Gonkhom, Sysouph. & Thongkl. sp. nov. Fig. 4 Diagnosis. Epigeous basidiomata with irregular club shape, smooth to slightly cracked to squamulose peridial head, brown to burnt umber, sessile or short pseudostipitate stipe, white, pale brown context, with hyphae simple-septate in both endoperidium and exoperidium, dark brown globose to subglobose basidiospores with crowded spines. Holotype. Thailand • Chiang Rai Province, Mueang Chiang Rai District, 16 July 2010, collected by Naritsada Thongklang, NTF 062 (MFLU 19-1345). Etymology. The species name “ magnisporum ” refers to its larger basidiospores. Description. Basidiomata epigeous, 35 mm in height, 22–34 mm in diam., club-shaped, with an irregularly globular peridial head; surface smooth, slightly cracked to squamulose, brown (6 E 5) to burnt umber (6 F 6), on pale orange (5 A 3) background. Sessile or short pseudostipitate (10 mm high), brown (6 E 5). Context thick, up to 5 mm wide. Exoperidium composed of hyphae simple-septate, interwoven, hyaline to yellow, 4.1–5.8 µm in diam. Endoperidium layer formed by hyphae simple-septate, with slightly thickened walls, interwoven, hyaline, 5.8–9.6 µm in diam., and hyphae from the endoperidium toward the gleba are pale yellow (4 A 3) and black in the mature gleba. Clamp connections present on endoperidium hyphae. Basidiospores (n = 50) globose to subglobose, echinulate with crowded curved spines, dark brown in KOH, (7.67 –) 12.42–8.42 (– 13.46) × (10.33 –) 14.53–11.42 (– 15.50) µm including ornamentation. Basidia not seen. Habitat and distribution. Solitary on soil, epigeous, in northern Thailand. Known distribution. Northern Thailand. Note. Scleroderma magnisporum is characterized by a smooth, slightly cracked surface and larger basidiospores. The microcharacter of S. magnisporum is similar to that of S. hypogaeum Zeller. However, S. hypogaeum, originally described from Oregon, has a smooth, slightly cracked, or subscaly basidiome, with larger basidiospores up to 22–30 μm diam. (Zeller 1922; Guzmán et al. 2013). S. magnisporum is phylogenetically close to Scleroderma microcarpum (MFLU 19-1347) in this study (Fig. 1). Both species are clearly different in their basidiomata size and shapes; the basidiomata of S. microcarpum are much smaller than those of S. magnisporum (7.6–15.5 µm diam.). While S. yunnanense shares with S. magnisporum a smooth to faintly cracked peridium and large basidiospores (15–20 μm), it has a pale yellow to ochre peridium (Guzmán 1970; Zhang et al. 2013).