Xanthagaricus guangzhouensis Kun L. Yang, Jia Y. Lin & Zhu L. Yang, sp. nov.
Creators: name: Yang, Kun L.
name: Lin, Jia Y.
name: Li, Guang-Mei
name: Liu, Zhen-Chao
name: Hosen, Md. Iqbal
name: Yang, Zhu L.
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Fungi
Basidiomycota
Agaricomycetes
Agaricales
Agaricaceae
Xanthagaricus
Xanthagaricus guangzhouensis

description: Xanthagaricus guangzhouensis Kun L. Yang, Jia Y. Lin & Zhu L. Yang, sp. nov. (Fig. 7)
Registration identifier:— FN571940
Etymology:— Named after Guangzhou, the city where the holotype of this species was collected.
Diagnosis:— Similar to X. chamaeleontinus and X. ianthinus, but differing from them by brownish squamules on stipe and bluish lamellae.
Type:— China, Guangdong Province, Guangzhou City, Nansha District, Huangshanlu Forest Park, a green belt along Dengshan Rd., on soil, 22°46’22”N, 113°34’21”E, elevation 90 m, April 15, 2023, Kun L. Yang & Jia Y. Lin, K 23116 (HKAS133455, holotype! (ITS: PP736697; nrLSU: PP732927; tef-1α: PP746818); HTBM0631, isotype!).
Description:— Basidiomata tiny. Pileus 5–8 mm in diameter, hemispherical to convex; background conch white (#EFEFF7) to periwinkle blue (#CDCFE5); squamules more or less flaky at center, becoming granular towards margin, wisteria violet (#C5BBDC) to rosewood red (#78545C), becoming lighter towards margin; margin with appendices conch white (#EFEFF7); context ceramic white (#FEFEFA) to merino white (#F9F5EC) when fresh, without a color change or becoming darker after damaged. Lamellae free, subdistant to nearly crowded, pale periwinkle blue (#C9D4E6) to dull pigeon blue (#A9B5C3), with a slightly serrate edge; lamellulae abundant. Stipe 7–10 mm long, 1 mm thick, cylindrical, slightly curved; background ceramic white (#FEFEFA) to pale bone brown (#E7D5C7); squamules furfurous, usually more abundant below the annulus, merino white (#F9F5EC), lacewood brown (#D5B7A1) to mire brown (#B89F89); context ceramic white (#FEFEFA) to merino white (#F9F5EC) when fresh, turning sandal brown (#BA8B70) or becoming darker after damaged; base without tomenta. Annulus superior, easily broken and fugacious, concolorous with the squamules on the stipe. Odor unknown. Taste unknown.
Basidiospores [40/2/2] 4–5 [4.26 ± 0.35, 4.00] × 2.5–3 (3.5) [2.94 ± 0.23, 3.00] µm, Q = (1.29) 1.33–1.67 [1.46 ± 0.13, 1.33], broadly ellipsoid to ellipsoid, slightly thick-walled, smooth under both LM and SEM, tinged withered green (#D5DCB7) to muck green (#92A890) in both water and 5% KOH, with a small apiculus, without a germ pore. Basidia 11–13.5 × 5–6 μm, clavate, 4-spored, thin-walled, nearly colorless in both water and 5% KOH, with sterigmata up to 2 µm long, surrounding by basidioles measured 10–15 × 3.5–5.5 μm. Lamella trama regular to subregular, composed of 4–11 µm wide, cylindrical to subcylindrical, thin-walled, nearly colorless in water and 5% KOH, compact, moderately to frequently branching hyphae. Cheilocystidia very abundant, 12.5–26 × 4–8 µm, clavate, ovoid, subcylindrical to slightly flexuose, thin-walled, smooth, nearly colorless in both water, and 5% KOH. Pleurocystidia absent. Pileus squamules epithelioid, composed of globose, subglobose to broadly ellipsoid, slightly thick-walled and encrusted cells measured 8–16 × 7.5–13 µm, tinged tea orange (#EFDFA0) in both water and 5% KOH. Stipe squamules structured as the same as the pileus squamules but brighter-colored, tinged butter orange (#F2DF8F) in both water and 5% KOH. Clamp connections absent in all tissues.
Habitat and distribution:— Solitary to gregarious, seldom weakly caespitose, scattered on the soil as individuals, in urban green belts. Currently known from China (South China).
Additional collection examined:— China, Guangdong Province, Guangzhou City, Nansha District, Huangshanlu Forest Park, a green belt along Dengshan Rd., on soil, 22°46’22”N, 113°34’21”E, elevation 90 m, April 15, 2023, Kun L. Yang & Jia Y. Lin, K 23117 (HTBM0632 (ITS: PP736657; nrLSU: PP732888; tef-1α: PP746819)).
Additional notes: This species is rare. After we got the two collections on April 15, 2023, we haven’t seen it again, even at the locality where it was found originally.
description: Published as part of Yang, Kun L., Lin, Jia Y., Li, Guang-Mei, Liu, Zhen-Chao, Hosen, Md. Iqbal & Yang, Zhu L., 2024, Heinemannomyces, Hymenagaricus and Xanthagaricus revisited (Basidiomycota, Agaricaceae), pp. 112-164 in Phytotaxa 659 (2) on page 133, DOI: 10.11646/phytotaxa.659.2.2, http://zenodo.org/record/13217850