Gautieria zixishanensis L. Li, K.D. Hyde & S.H. Li, 2025

Gautieria zixishanensis L. Li, K.D. Hyde & S.H. Li , sp. nov.

Figure 2 View FIGURE 2 .

MYCOBANK MB 856847

Diagnosis: Differs from other Gautieria species by its basidiomata have an obvious base attached with a white basal rhizomorph; basidiomata surface tomentose, pseudoperidium intact and not easy to fall off when mature, without foveate-porate, ridges invisible; and light golden-brown longitudinal ridges basidiospore up to 17–22 μm length.

Etymology: zixishanensis, refers to the type locality of the Zixishan Mountain.

Holotype: China, Yunnan, Chuxiong, Zixi Mountain , 25°00′ N 101°23′ E, alt. 2053.7 m, in a mixed forest of Pinus yunnanensis Franch. and Quercus sp. , 2 November 2023, Lin Li, BMDU L23106 (GenBank: ITS = PQ672295 nrLSU = PQ672297 ). GoogleMaps

Basidiomata pseudoperidial, 1–2 cm in diameter, subglobose to reniform, with a basal depression connected to abundant white basal rhizomorphs, 0.5–1.5 mm diameter thick, surface tomentose, with hairs easily detached upon friction, pseudoperidium completely covered a basidioma and not easy to fall off when mature, not foveate or porate, pale yellowish white (4A2) when freshly unearthed, with brownish (7D5) patches gradually appearing after exposure to air or rubbed, becoming wrinkled and darker (4D7) after drying, becoming black when treated with FeSO 4. Ridges invisible. Gleba fleshy brown (8C7) to golden brown (5D7), composed of crowded, irregularly shaped to radially elongated, narrow, sinuous, inordinate, small locules sized 0.2–1 × 0.1–0.5 mm covered by yellow-brown to yellowtan hymenium. Tramal plates white to almost transparent. Columella dendroid, widest at the base, up to 2–3 mm, branching towards the top, consists of hyaline interwoven hyphae 0.5–1.0 μm in diameter, white to hyaline, gelatinous, hard and brittle. Odour pleasant.

Pseudoperidium 110–230 µm thick, composed of two layers: outer layer a trichotomentocutis, 60–140 µm thick, composed of light reddish brown (4B4) interwoven hyphae of 5–10 μm in diameter, thin-walled, septate; inner layer 45.5–90 µm thick, composed of hyaline, nearly parallel interwoven hyphae 0.5–1.5 μm in diameter, dense, and seeming gelatinous. The boundary between the inner and outer layers indistinct.

Hymenophoral trama 64–110 μm thick, composed of slightly gelatinized, hyaline interwoven hyphae, without a color change in contact with FeSO 4.

Basidia clavate, thin-walled, 31.5–45.0 ×7.5–14.0 µm, 2-spored. Paraphysoid cells abundant, 15–40 × 3–9 μm, with polymorphic terminal cell, cylindrical, clavate, narrow pyriform.

Basidiospore ovate to broadly ovate (shape including the thickened exosporium), light golden yellow (4B8), cyanophilous, non-amyloid, measured (16.0–) 17.5–22.0 (–24.0) × 11.0–14.5 μm (including exosporium), Q (L/I) = 1.30–1.81, Qm = 1.56 ± 0.15 (n = 50). Exosporium thin and almost transparent when immature, thickening and forming 7–11 longitudinal ridges 2.2–2.9 μm high following maturity. Apical ring prominent, sometimes exhibiting irregular protrusions, with a central depression approximately 1 μm in diameter. The ends of the ridges merged seamlessly with the apical ring. Hilar appendix 2–3 μm long, conico-truncate, with a hilum 0.5–1 μm in diameter, without or with very short remnants of sterigma.

Ecology and distribution: Hypogeous, solitary or gregarious, in a mixed forest of Pinus yunnanensis and Quercus sp. , alt. 2020–2050 m, fruiting in winter. Known only from Yunnan Province, China.

Additional specimen examined: China, Yunnan Province, Chuxiong, Zixi Mountain, 25°00′ N 101°23′ E, alt. 2038 m, 2 November 2023, Lin Li (GenBank: BMDU L23107 GenBank: ITS = PQ672296 nrLSU = PQ672298).

Notes: The phylogenetic tree indicates that the newly described species, Gautieria zixishanensis , is closely related to the known species G. hymenogastroides , with both species forming a single clade within sect. Hymenogastroides. Comparatively, in terms of macroscopic characteristics, although both species have pseudoperidial basidiomata, G. hymenogastroides exhibits a tomentose surface with lemon-yellow hues and a foveate-porate pseudoperidium that shows purplish oxidation when rubbed ( Vidal et al. 2023). In contrast, the pseudoperidium surface of G. zixishanensis completely covers the basidiomata, does not present foveate-porate structures, and is pale yellowish-white, turning brownish when rubbed, with invisible ridges. Moreover, at the microscopic level, the spores of both species are similarly colored, but the spores of G. hymenogastroides are larger. Additionally, G. hymenogastroides has more diverse paraphysoid cell morphologies, including pyriform, papillate, or attenuate terminal cells, which are absent in G. zixishanensis . Furthermore, G. hymenogastroides is distributed in the Mediterranean region, found in Northern Spain at altitudes between 500–1100 m in montane broadleaf forests ( Castanea , Fagus , Quercus ), while G. zixishanensis is distributed in the subtropical low-latitude plateau with a monsoon climate, found in central Yunnan, China, at altitudes between 2020–2050 m in mixed forests ( Pinus , Quercus ). Molecular analysis also shows that G. zixishanensis is separated from other Gautieria species, and they were divided into different species generally with a high statistic support.