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

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

Figs 8 View Figure 8 , 9 View Figure 9

Holotype.

China • Guangdong Province, Guangzhou, Huangpu District, Shuangchuanshi Mts. , 23°11'N, 113°32′E, elev. 69.6 m, on the fallen angiosperm leaves, 14 May 2024, CLZhao 35992 ( SWFC). GoogleMaps

Etymology.

Trachelium (Lat.): referring to the species having a long stipe.

Description.

Fruiting body: Unexpanded basidiomata, 9–12 mm in diameter, ellipsoidal to fusiform, white to pink. Expanded basidiomata small to medium sized, 2–3 cm in diameter, 1.5–2 cm in height, and long stipe (height 0.5–1 cm). Exoperidium: deep saccate, dehiscence often halfway down, splits into 5–6 lobes at maturity, lobes 5–10 mm wide, tapered at the front end, exoperidium attached to the rhizomorphs, soft and thin upon drying. Mycelial layer: cream to clay-buff when fresh, without debris, not easily dislodged, turning to clay-buff when dry. Fibrous layer: white, tightly attached to the mycelial layer. Pseudoparenchymatous layer: smooth surface, cream to flesh pink when fresh, not deciduous, aseptic collar, turning to gray brown, thinner when dry.

Endoperidial body: Globular, 10–13 mm in diameter, projecting apically, 1–3 mm length, sessile. Endoperidium ash-gray, with a smooth surface and buff villus visible under the dissecting microscope. Peristome wide conical, fibrillose, ash-gray to dark gray, distinctly delimited.

Hyphal structure: Capillitial hyphae: 3–4.5 µm in diameter, thick-walled, slightly yellowish, unbranched, IKI –, CB –; tissues unchanged in KOH. Exoperidium mycelium layer outside, mycelium hyphae slightly thick-walled to solid, 2.2–3.1 µm in diameter; fibrous layer in the middle, formed of the interlacing filament tissue, fibrous hyphae slightly thick to thick-walled, 2.5–3.3 µm in diameter; pseudoparenchymatous layer inside, formed of the angular cell structured, 22–56 × 14.5–33 µm.

Basidiospores: Spherical, (3.5 –) 3.7–4.3 (– 4.6) × (3.5 –) 3.8–4.3 (– 4.6) µm in diameter, grayish brown to dark brown, IKI –, CB –; spore surface with delicately echinulate, 0.4–0.9 µm in length, Q = 1.01, Q m = 1.01 ± 0.01. Basidia flask shaped, 13.5–18.5 × 6–9 μm, with 6 inconspicuous basidial pedicels.

Additional specimens examined

(paratypes). China • Guangdong Province, Guangzhou, Huangpu, Shuangchuanshi Mts. , 23°11'N, 113°32'E, elev. 69.6 m, on the fallen angiosperm leaves, 9 May 2024, CLZhao 35939; 1 June 2024, CLZhao 36055 ( SWFC) GoogleMaps .

Notes.

Based on ITS + nLSU + RPB 1 + ATP 6 data (Fig. 1 View Figure 1 ), G. trachelium was sister to G. suae . The species G. trachelium resembles G. yanshanense and G. hirsutum in sharing sessile endoperidial body. However, G. yanshanense differs from G. trachelium by its smaller basidiospores (2.7–3.2 × 2.8–3.3 µm, Zhou et al. 2022); G. hirsutum can be distinguished from G. trachelium by its subglobose to obovate unexpanded basidiomata, and smaller basidiospores (2.5–3 μm, Baseia and Calonge 2006).