Scleroderma navigatum Kun L. Yang, Jia Y. Lin & Zhu L. Yang 2025, sp. nov.

(2.3) Scleroderma navigatum Kun L. Yang, Jia Y. Lin & Zhu L. Yang, sp. nov. (Fig. 12) Registration identifier:— FN572388 Etymology:— Referring to an earthball species navigating with its host plants across seas. Diagnosis:— Differing from other species in sect. Sclerangium known in Oceania and Asia by the nearly smooth peridium and the basidiospores mostly 9.5–12.5 µm in diameter. Type:— China, Guangdong Province, Guangzhou City, Tianhe District, South China Agricultural University, Arboretum, 23°09'27"N, 113°21'22"E, elevation 40 m, April 8, 2024, Jia Y. Lin, L24074 (HKAS145954, holotype (deposited in the Herbarium of Cryptogams in Kunming Institute of Botany of Chinese Academy of Sciences; ITS: PV059092; nrLSU: PV054264); HTBM1948, isotype). Description:— Basidiomata small, 18–35 mm in diameter, 14–27 mm in height, subglobose to tuberiform, sessile; odor strongly fungal; taste unknown. Peridium leathery, 1–1.5 mm thick, merino white (#F9F5EC), pale dirty orange (#FAF4E3) to beach yellow (#F9F3C9), turning reddish after damaged, with fibrous, concolorous squamules to nearly smooth. Gleba compact at first, becoming pulverulent, dull black (#0B0C0E). Basal rhizomorphs moderately abundant, whitish. Basidiospores {40/3/3} (9) 9.5–12.5 (14) [10.68 ± 1.04, 10.00] µm in diameter including ornamentation, mostly globose, rarely subglobose, thick-walled, with echinulate ornamentation 0.5–1 µm high, brownish to purplish, often surrounded by remnants of placental cells. Basidia collapsed. Gleba trama composed of 2.5–5.5 μm wide, thin- to slightly thick-walled, nearly colorless, compact, moderately branching, interwoven hyphae with clamp connections. Peridial surface composed of 2–6.5 μm wide, slightly thick-walled, nearly colorless to slightly brownish, moderately compact, moderately to frequently branching, interwoven hyphae with clamp connections. Peridial trama composed of 2.5–4.5 μm wide, thin- to slightly thick-walled, nearly colorless to slightly brownish, compact, moderately to frequently branching, subregularly arranged hyphae with clamp connections. Habits and distribution:— Gregarious, on soil, in forests, associated with plants of Myrtaceae. Currently known from Asia (China) and Oceania (Australia) with molecular evidence. Other collections examined:— China, Guangdong Province, Guangzhou City, Tianhe District, South China Agricultural University, Arboretum, 23°09'27"N, 113°21'22"E, elevation 40 m, April 8, 2024, Jia Y. Lin, L24075 (HTBM1949) & L24076 (HTBM1950). Notes:— This fungus was found in a plantation in South China Agricultural University dominated by Eucalyptus cf. robusta trees introduced from Australia. Interestingly, two ITS sequence samples labeled as “Uncultured fungus” from Australia (HFEhyp5 & Toohyp34) clustered with our collections of this fungus as a single phylogenetic species (Fig. 1), implying that this fungus in China may be aliens carried by Eucalyptus plants from Australia.