Geastrum fibulatum X. Yang & C. L. Zhao, 2025

Geastrum fibulatum X. Yang & C. L. Zhao sp. nov.

Figs 4 View Figure 4 , 5 View Figure 5

Holotype.

China • Jiangsu Province, Nanjing, Jiangning County, Diaoyutai Mountain , 31°58'N, 118°55'E, elev. 93.1 m, on the ground, 28 May 2024, CLZhao 36068 ( SWFC). GoogleMaps

Etymology.

Fibulatum (Lat.): referring to the generative hyphae with clamp connections of type specimen.

Description.

Fruiting body: Expanded basidiomata small to medium-sized, 4–6 cm in diameter, 1–2.5 cm in height. Exoperidium: shallowly saccate to deep saccate, dehiscence often greater than halfway, splits into 5–6 lobes at maturity, lobes 8–18 mm wide, lobes long and mostly rolled outward, toughened and thin upon drying. Mycelial layer clay buff to grayish brown when dry, without debris, not easily dislodged. Fibrous layer white, tightly attached to the pseudoparenchymatous layer. Pseudoparenchymatous layer smooth surface, white to cream when fresh, cinnamon-buff to olivaceous to grayish brown to fuscous when dry, not deciduous, aseptic collar, thin when dry.

Endoperidial body: Globular, 15–25 mm in diameter, projecting apically, 1–5 mm length, sessile. Endoperidium of clay pink to clay buff, with a smooth surface and grayish villus visible under the dissecting microscope. Peristome silky fibrillose, color lighter than the endoperidium, distinctly delimited.

Hyphal structure: Capillitial hyphae 3–6 µm in diameter, thick-walled, olivaceous buff, unbranched, IKI –, CB –; tissues unchanged in KOH. Exoperidium mycelium layer outside, dimitic hyphal system; generative hyphae with clamp connections, thin-walled, colorless, 3.5–6 µm in diameter, skeletal hyphae thick-walled to subsolid, slightly yellowish, 3–5.5 µm in diameter; fibrous layer in the middle, formed of the interlacing filament tissue, fibrous hyphae thick-walled to solid, 2.5–6 µm in diameter; pseudoparenchymatous layer inside, formed of the angular cell structured, 18–54 × 10–26 µm.

Basidiospores: Spherical, 3–3.6 (– 4) × 3–3.5 (– 4) µm in diameter, brown, thick-walled, to grayish brown, IKI –, CB –; spore surface with ornamentation verrucose, 0.5–0.8 (– 1) µm in length, Q = 1.01, Q m = 1.01 ± 0.01.

Additional specimens examined

(paratypes). China • Jiangsu Province, Nanjing, Jiangning County, Diaoyutai Mountain , 31°58'N, 118°55'E, elev. 93.1 m, on the ground, 28 May 2024, CLZhao 36066; CLZhao 36067; CLZhao 36069 ( SWFC) GoogleMaps .

Notes.

Based on dataset of ITS + nLSU + RPB 1 + ATP 6 data (Fig. 1 View Figure 1 ), Geastrum fibulatum was sister to G. michelianum . The taxon G. fibulatum resembles G. fuscogleba and G. melanocephalum in sharing verrucose basidiospores. However, G. fuscogleba differs from G. fibulatum by its arched expanded basidiomata, and its larger basidiospores (4.5–7 µm, Domínguez and Castellano 1996); the species G. melanocephalum can be distinguished from G. fibulatum by its endoperidial body with stalk, and arched expanded basidiomata ( Jeppson et al. 2013).