Inocybe fulvobasalis Zhu L. Yang & Zi X. Yu sp. nov.
Fig. 4
Etymology.
The epithet “ fulvobasalis ” refers to the characteristic persistently yellow-brown base of the stipe throughout the ontogeny of this species.
Diagnosis.
Inocybe fulvobasalis can be distinguished from other species in the I. lilacina subgroup by its grayish lilac pileus, which is hemispherical to subumbonate when young, as well as its stipe with a persistently yellow-brown base throughout ontogeny.
Holotype.
China • Yunnan, Diqing Zang Autonomous Prefecture, Shangri-La City, Potatso National Park, in a temperate broad-leaved and coniferous mixed forest with trees of Picea, Abies and Quercus acutissima, 27°52'48"N, 99°57'00"E, alt. 3613 m, 11 September 2023, Wei-Chao Feng 0064 (KUN-HKAS 154762. GenBank no.: ITS: PZ 280621; LSU: PZ 280630; rpb 2: PZ 284721).
Description.
Basidiomata small to medium-sized. Pileus 10–40 mm in diameter, hemispherical to subumbonate when young, gradually expanding to convex or plano-convex with age, often with an indistinct central umbo; surface hygrophanous, pale lilac (15 A 2, 15 A 3) to grayish lilac (16 B 2, 16 B 3) throughout when young, with the umbo often tinged with pale brownish (4 B 5–4 B 8) buff, the disc and umbo fade to yellowish (3 A 3–3 A 6) with age; margin initially incurved, becoming depressed to straight with age, often retaining faint lilac (15 A 2, 15 A 3) tones, occasionally with an orange-brown tinge (6 A 3–6 A 5), silky-fibrillose; context of pileus white (1 A 1) to pale whitish gray (1 B 1), odor strongly spermatic. Lamellae emarginate to sinuate, crowded, 3–5 mm broad, alternately distributed with 1–3 tiers of lamellulae, subventricose, pale grayish lilac (15 A 2, 15 B 2) when young, becoming pale yellowish (4 A 2–4 A 4) when old; edges indistinctly pallid-fimbriate. Stipe 37–87 × 2–5 mm, cylindrical, pale grayish lilac (15 A 2, 15 B 2) when young, the apex bearing the most intense lilac tones, occasionally becoming pale yellow (1 A 2–1 A 5) overall with age, the base consistently tinged with stable yellowish brown (3 A 5, 3 B 5) to light brownish (4 A 7, 4 B 7) buff; with upper 1 / 8–1 / 6 distinctly pruinose, faint longitudinal fibrillose striations present towards the base; cortina fugacious, occasionally leaving fugacious, ephemeral annular remnants on the upper stipe.
Basidiospores [100 / 4 / 4] (9.0) 9.5–10.0 – 11.0 (12.0) × (5.0) 5.5–6.0 – 7.0 (7.2) μm, Q = (1.5) 1.57–1.67 – 1.83 (2.2), Qm ± SD = 1.67 ± 0.13, ellipsoid to slightly amygdaliform, yellowish brown in KOH, slightly thick-walled, smooth, typically with a prominent central lipid droplet; germ pore absent; apiculus small but distinct. Basidia 15–32 × 6–13 µm, narrowly clavate to clavate, hyaline in 5 % KOH; mostly 4 - spored, sometimes 2 - spored; sterigmata up to 5 µm long. Pleurocystidia 52–75 × 16–22 µm, narrowly utriform or fusiform with a basal pedicel, occasionally ovoid, thick-walled (ca. 0.5–2 μm thick), pale yellowish green or hyaline in 5 % KOH; apices obtuse and crystalliferous. Cheilocystidia 55–75 × 13–20 µm, similar to pleurocystidia, but sometimes with a more slender and elongated neck. Cheiloparacystidia 8–27 × 5–20 µm, clavate, elliptical or subglobose, thin-walled, smooth, hyaline, mixed with cheilocystidia. Caulocystidia 53–95 × 10–19 µm, similar to hymenial cystidia, mostly narrowly lageniform. Cauloparacystidia 13–35 × 9–15 µm, clavate, elliptical or subglobose, thin-walled to slightly thickened, hyaline, abundant. Pileipellis a cutis, composed of slender and cylindrical, thin-walled, hyaline hyphae 3–8 μm wide. Pileal trama subregularly arranged, composed of thin-walled hyphae 7–25 μm wide. Hymenophoral trama regularly to subregularly arranged, composed of cylindrical to clavate, thin-walled, smooth, hyaline hyphae 3–15 μm wide. Stipitipellis regularly arranged, composed of cylindrical, hyaline to pale yellow hyphae 5–16 μm wide. Clamp connections common in all tissues.
Habitat.
Gregarious on soil in temperate broad-leaved and coniferous mixed forests with trees of Picea, Abies and Quercus acutissima, or in coniferous forests with trees of Abies and Rhododendron.
Distribution.
Currently known only from southwestern China.
Additional specimens examined.
China • Yunnan, Diqing Zang Autonomous Prefecture, Shangri-La City, Potatso National Park, in a temperate broad-leaved and coniferous mixed forest with trees of Picea, Abies and Quercus acutissima, 27°52'48"N, 99°57'00"E, alt. 3521 m, 11 September 2023, Wei-Chao Feng 0045 (KUN-HKAS 154761); China • Yunnan, Diqing Zang Autonomous Prefecture, Shangri-La City, near Longmu Middle Bridge, East Ring Road, in a temperate broad-leaved and coniferous mixed forest with trees of Picea, 27°42'18"N, 100°00'39"E, alt. 3474 m, 13 September 2023, Ze-Wei Liu 291 (KUN-HKAS 154763); China • Xizang, Linzhi, Zayu County, Chawalong Township, Jiaying Village, in a coniferous forest with trees of Abies and Rhododendron, 28°30'59"N, 98°31'29"E, alt. 4027 m, 11 August 2022, Xiang-Hua Wang 10448 (KUN-HKAS 130373).
Notes.
Inocybe fulvobasalis is characterized by a grayish lilac pileus, with the umbo often tinged with pale brownish buff, and a grayish lilac stipe with a persistently yellow-brown base.
Phylogenetically, I. fulvobasalis is located in the I. geophylla (Fr.) P. Kumm. group and forms a sister clade to the I. lilacina subgroup, which consists of I. pallidicremea Grund & D. E. Stuntz, I. ionocephala Matheny, I. lilacina (Peck) Kauffman and I. sublilacina Matheny & A. Voitk (Matheny 2005; Ryberg et al. 2010; Matheny and Swenie 2018). Morphologically, I. fulvobasalis is easily confused with I. pallidicremea and I. ionocephala. However, I. pallidicremea differs in often being obtusely conical when young, having a deeper purple coloration, a more prominent umbo at maturity, and slightly smaller basidiospores (9.0 × 5.3 μm vs. 10.0 × 6.0 μm) (Grund and Stuntz 1977; Lincoff 1981; Matheny and Swenie 2018); I. ionocephala is separated by its white stipe throughout the entire ontogeny (Matheny and Swenie 2018). Inocybe lilacina can be distinguished by its brighter, more vivid overall purple coloration, and a deeply purple pileus disc that is significantly more persistent through development (Peck 1874; Kauffman 1918, 1924; Matheny and Swenie 2018). Inocybe sublilacina differs in its conical pileus in young basidiomata, and the stipe base that fades to white at maturity (Matheny and Swenie 2018).
Publication Date: 2026-06-05